Pressure Accumulator

Abstract

The accumulator comprises an accumulator housing (10), a movable separating element (16) for fluid-tightly separating a medium space (12), preferably filled with a working gas, from a fluid space (14), and a monitoring device (28) for providing a visually perceptible indication in the event of a fault impairing the sealing effect of the separating element (16), the monitoring device (28) having a sight window communicating with the medium space (12) and through which an indicator can be observed, the optical property of which is perceptibly changed when wetted with a fluid, the monitoring device (28) having a threaded plug whose external thread can be screwed into a corresponding internal thread of the accumulator housing (10), and further having a fluid-permeable shut-off device in addition to the sight window and the indicator, the threaded plug being delimited by the sight window and forming an accommodation space in the threaded plug for accommodating the indicator, the accommodation space being spatially separated from the interior of the medium space (12) of the accumulator housing (10).

Description

[Technical field]

[0001] The present invention relates to a pressure accumulator having an accumulator housing, in which a movable separation element fluid-tightly separates a media space, preferably filled with a working gas, from a fluid space, and which is provided with a monitoring device, which gives a visually perceptible indication in the event of a fault impairing the sealing effect of the separation element and which has a sight window communicating with the media space and through which an indicator, the optical properties of which change perceptibly when wetted with a fluid, can be observed. [Background technology]

[0002] EP 1 399 636 A1 discloses a universal pressure accumulator, in which an indicator that changes optical properties is accommodated in a capsule, the capsule wall of which is permeable for the passage of fluids, the capsule being arranged between a sight glass and a separating element in the accumulator housing. The known solution allows a space-saving design of the entire monitoring device due to the low construction height of the capsule with the indicator accommodated therein. The capsule-shaped indicator, the fluid-permeable blocking device for holding the capsule-shaped indicator in a defined position in the accommodation space and the sight glass are arranged one behind the other at a distance in a sleeve-shaped receiving socket provided on the upper side of the accumulator housing. In this case, the sight glass is metal-welded to the wall of the accumulator housing and the monitoring device as a whole is provided in such a way that it remains permanently accommodated in the accumulator housing and is therefore an integral part of the accumulator housing. Furthermore, in known solutions, an additional sealing body is arranged on the upper side of the accumulator housing alongside the monitoring device, which allows a gas-tight seal of the associated filling port in the housing wall, which is provided for filling the medium space with a working gas, in particular in the form of nitrogen gas. In addition to the increased manufacturing effort for fitting the filling port into the accumulator housing wall and sealing it with a sealing plug, this sealing plug is often made of a soft solder with poor elasticity, so that uninterrupted operation is not always guaranteed, especially in high-pressure applications. Furthermore, the filling effort for refilling the medium space with the working gas is increased, since the soft solder of the sealing plug has to be removed in a relatively laborious manner and then reattached to seal against the filling port after the filling operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 179800 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to improve the known solutions based on the prior art while retaining such advantages as reduced manufacturing effort and easier filling and refilling operations with working gas on the so-called gas side of the pressure accumulator. The corresponding object is achieved by an accumulator having in its entirety the features set forth in patent claim 1. [Means for solving the problem]

[0005] According to the characterizing features of patent claim 1, the monitoring device has a threaded plug, the external thread of which can be screwed into an assigned internal thread of the accumulator housing, the threaded plug having a sight window, an indicator and a fluid-permeable shut-off device, which shut-off device forms a receiving space in the threaded plug, partially delimited by the sight window and intended to receive the indicator, the shut-off device spatially separating this receiving space from the interior of the medium space of the accumulator housing, all the essential components of the monitoring device or the indicator device being accommodated in one component, in particular in the threaded plug, by means of an associated threaded joint, usually in the form of an internal thread in the accumulator housing which delimits the filling port, when the threaded plug is accordingly removed, whereby both the initial filling of the gas side of the accumulator with working gas and, if necessary, the corresponding refilling operation are facilitated. Due to the centralized integration of the components of the monitoring device in one place in the associated threaded plug, the solution according to the invention has a compact design and proves to be extremely stable under pressure.

[0006] Furthermore, the threaded plug is capable of absorbing very high compressive forces, so that even if the accumulator is used in high-pressure applications, there is no need to weaken the accumulator housing by means of a separate filling port, which must be additionally sealed, as in the prior art, and a fault-free closure solution is provided. In order to ensure the pressure resistance and tightness of the accumulator housing by means of the threaded plug, it is further provided that the threaded plug, designed as a hollow screw, has a frusto-conical receptacle, at least in the region of the screw head, for accommodating a sight glass, the obliquely extending conical wall of which in an imaginary extension forms an acute angle with the longitudinal axis and the circumference of the accumulator housing, and further that the sight glass, preferably made of borosilicate glass, is metal-fused to the metal material of the threaded plug.

[0007] More preferably, the sight glass is broken when a pre-determinable target pressure threshold between the test pressure and the burst pressure is exceeded, and the corresponding sight glass is provided to shatter into very small pieces upon failure or bursting. Unlike the prior art metal sealing solder, which may fly like bullets when broken, the shattered glass remains mostly in the screw plug, thus avoiding endangering the surroundings.

[0008] In a further preferred embodiment of the accumulator according to the invention, it is provided that the indicator is freely movable within the receiving space, so that in the event of a fault, the indicator is supported below the sight window, the optical observation distance is shortened and the indication of the indicator is easier to read, and in this way it is prevented that in the event of a fault due to a sudden high pressure occurring in the receiving space, the indicator is destroyed under unfavourable conditions and the indicator is no longer displayed.

[0009] In a further preferred embodiment of the accumulator according to the invention, it is provided that the frusto-conical receptacle with the sight glass transitions into a ring-groove-shaped enlargement in the threaded plug, which is part of the accommodation space for the indicator, such that in the event of relevant burst pressures occurring from the side of the accumulator, these burst pressures are guided to the enlargement, which, although it may increase the pressure load on the metallic material of the threaded plug, ensures a substantial pressure relief for the glass sight glass, which, due to the conical shape of the receptacle in the threaded plug, is reliably fixed in the threaded plug and is held even in the event of high burst pressures, so that it is unlikely for the sight glass to fly out unintentionally like a bullet.

[0010] In order to improve the sealing, the threaded plug is preferably provided with additional sealing material in the area of ​​the top side and / or bottom side in relation to the respective transition to the accumulator housing, and furthermore it is possible to fix the threaded plug to the accumulator housing by applying an additional weld seam.

[0011] If the indicator becomes depleted, for example because it indicates a fault by a change in colour, it becomes evident that after carrying out maintenance or repair work on the accumulator, replacing the entire threaded plug together with the used indicator with a correspondingly designed new threaded plug is sufficient to make the entire arrangement functional again and is very cost-effective.

[0012] The invention further relates to a threaded plug, in particular a threaded plug for a pressure accumulator, which is arranged as an integral component in a threaded housing. A viewing window and An indicator; and a shutoff device that is designed to be fluid permeable and that holds the indicator within the receiving space of the screw housing.

[0013] Further advantageous configurations of the accumulator are the subject of further dependent claims. In the following, the solution according to the invention is explained in more detail on the basis of an embodiment according to the drawings, which are schematic and not drawn to scale. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 shows a longitudinal section through a pressure accumulator with a threaded plug inserted according to one embodiment. [Diagram 2] FIG. 2 shows an enlarged view of the threaded plug inserted into the accumulator housing according to the image of FIG. [Diagram 3] FIG. 3 shows the threaded plug itself as inserted in FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 shows an accumulator in the form of a longitudinal section, with an accumulator housing 10 with a medium space 12 filled with a working gas, such as nitrogen gas, and a fluid or liquid space 14, which are fluid-tightly separated from one another by a movable separating element 16. In this embodiment, the separating element 16 is formed from a bellows known per se, which, as seen in FIG. 1, is fixed at its upper end by a fixing ring 18 inside the accumulator housing 10 and at its opposite lower end is hinged to a half-shell-shaped guiding device 20, which together with the bellows as separating element 16 can move up and down along the inside of the accumulator housing 10, and which can be connected to a fluid circuit, for example in the form of a hydraulic circuit, as the effect of the respective fluid pressure occurring at the connection 22. In this way, the movable separating element 16 is supported on its inside against the gas pressure in the medium space 12 and can store hydraulic energy, but also smooth out pressure pulses on the fluid side. Further advantageous embodiments of such an accumulator are possible, but as these are standard they will not be described in detail here. It goes without saying that instead of a bellows it is also possible to use other separating elements 16 (not shown) in the accumulator, for example in the form of a diaphragm bladder or a piston accumulator arrangement.

[0016] Furthermore, in this embodiment, the walls of the accumulator housing 10 are designed to be exceptionally thin-walled, and in this embodiment of the accumulator, the cylindrical wall of the accumulator housing 10 has a reinforcement 24 on the outer circumferential surface, which consists, for example, of a textile layer or textile windings. In this way, the accumulator housing 10, and thus the pressure accumulator, is reinforced and can also be used in high-pressure applications.

[0017] A monitoring device, generally designated 28, is attached to the upper side of the accumulator housing 10, which forms a kind of accumulator lid 26 having a dome shape and is shown in detail in FIGS. 2 and 3. The monitoring device 28 is arranged concentrically with a longitudinal axis 30 of the accumulator housing 10, which is formed rotationally symmetrical with respect to said longitudinal axis 30. The monitoring device 28 has as a housing body a threaded plug 32 designed as a hollow screw. The threaded plug 32 is divided into a base region with an external thread 34 and a head region with a threaded head 36, which is used to fasten the threaded plug 32 to the accumulator housing 10 by means of a conventional operating tool (not shown), such as, for example, a wrench.

[0018] Between the outer thread 34 and the screw head 36, a thread relief 38 is arranged. Furthermore, as shown in Figures 2 and 3, the screw plug 32 is designed as a plug or stopper, i.e. the height of the screw plug 32 is substantially equal to its width, which also contributes to the pressure stability of the entire construction of the accumulator housing 10 with the screw plug 32. The screw plug 32 has a sight window 40 which is located flush with the upper side of the screw plug 32 in the area of ​​the screw head 36. By means of the sight window 40, an indicator 42 can be observed, which communicates with the medium space 12 and changes its optical properties perceptibly when wetted by a fluid coming from the side of the fluid space 14. If, for example, the respective separating element 16 breaks and fails, liquid flows from the side of the fluid space 14 in the direction of the medium space 12 and from there further to the indicator 42, which then changes its color to make the observer aware that a failure has occurred in the pressure accumulator. Such optical monitoring can be performed by maintenance personnel, but a camera monitoring system (not shown) can also be used to automate the procedure.

[0019] In particular, as shown in Figures 1 and 2, a monitoring device 28 in the form of a threaded plug 32, the external thread 34 of which is screwed into the internal thread 44 of the accumulator housing 10, the threaded plug 32 having, as shown in the figures, on its underside a fluid-permeable shut-off device 46 which is preformed in a dome- or hemispherical shape towards the sight window 40 in the direction of the receiving space 48 for the indicator 42 in the threaded plug 32. The associated shut-off device 46 is formed from a sieve or membrane structure and is held in place by a press-fitted insert ring 50 formed in the lower end of the threaded plug 32, for example, or is a component of the threaded plug 32 which can be removed by means of a threaded joint not shown in detail. Due to the dome- or hemispherical configuration of the fluid-permeable shut-off device 46, increased pressure impulses originating from the medium space 12 and proceeding towards the receiving space 48 can be absorbed and compensated under the protection of this indicator 42.

[0020] Said receiving space 48 with the indicator 42 is partially delimited from above by the underside of the sight glass 40, from the outside by the inner circumferential wall of the threaded plug 32 and, as viewed in the figure, on the lower side by the shut-off device 46, so that a spatial separation occurs between the medium space 12 and the receiving space 48. The insert ring 50 is provided with a through-hole 52 which is arranged coaxially with a further through-hole 54 in the accumulator housing 10, thereby forming a fluid communication between the medium space 12 and the receiving space 48. The through-hole 52 and the further through-hole 54 are thus arranged concentrically with respect to the longitudinal axis 30 of the accumulator housing 10.

[0021] Said sight glass 40 consists of glass, preferably borosilicate glass, and is metal-fused to the material of the screw plug 32. The quality of the sight glass of the sight glass is in any case selected in such a way that in the event of breakage, when a predefinable target pressure threshold is reached between the test pressure in the receiving space 48 and the burst pressure, the glass breaks into very small fragments inside the screw plug 32 and, as a result, does not leave the screw head 36 of the screw plug 32. The screw plug forms a truncated cone-shaped receptacle 56 inside the screw head 36 on the head side, the sight glass 40 being enlarged on the side of the receiving space 48 by the above-mentioned inclination. As a result, the sight glass 40 is securely held in the screw head 36 of the screw plug 32 in the form of a plug, and even in the event of high pressure in the receiving space 48, the sight glass 40 is securely held in the screw plug 32 and does not fly out like a bullet into the outside surroundings. The receptacle 56 and the associated sight glass 40 are formed in a frustoconical shape, with their cross sections narrowing outwards, to ensure that in the event of breakage, the shattered glass cannot escape to the outside. In this respect, the sight glass 40 is arranged so that its upper side is flush with the free end face of the screw head 36.

[0022] The above-mentioned truncated cone-shaped receptacle 56 with the sight window 40 transitions into a ring-groove-shaped enlarged diameter section 58 in the screw plug 32, which is part of the accommodation space 48 for the indicator 42. The ring-groove-shaped enlarged diameter section 58 constitutes a free-through section that is larger than the outer diameter of the indicator 42 at its widest point and can therefore accommodate the indicator 42, which is freely movable within the accommodation space 48 in the event of breakage, and the indicator 42 can be supported below the sight window 40, which reduces the optical observation distance and makes it easier to read the indication of the indicator.

[0023] The indicator 42 comprises a fluid permeable capsule 60 made of two circular blanks, the upper of which is positioned along the periphery of the lower circular blank forming a beaded rim.

[0024] Details of this process are described in Patent Document 1. Inside the capsule 60 is contained an indicator material 62, which when in contact with a liquid such as hydraulic oil, changes color to a signal color red, making it possible to clearly indicate the presence of the indicator material. Details of this process are also described in Patent Document 1.

[0025] As can be seen in particular from figure 2, the upper part or accumulator lid 26 of the accumulator housing 10 is provided coaxially with its longitudinal axis 30 with a sleeve-shaped recess 64 which has an internal thread 44 on its inner circumferential surface and an end wall 66 on the bottom side which is penetrated by a further through-hole 54. As can be seen in particular from the installation diagram shown in figure 2, the engagement depth of the recess 64 is selected in such a way that, when the threaded plug 32 is screwed completely between its free lower end face 68 and the bottom 66 of the recess 64, an axial gap is preferably formed which can be used to accommodate a sealing material, not shown. Furthermore, further sealing means, not shown, for example in the form of a sealing ring, can be arranged in the transition between the threaded head 36 of the threaded plug 32 and the adjacent upper side of the accumulator housing 10 in the region of the thread relief 38. Furthermore, between the upper side of the accumulator housing 10 and the end region of the screw head 36, a thin-walled weld line can be fitted as a peripheral weld line 72 to fix the screw plug 32 in the assigned receptacle of the accumulator housing 10, which weld line also seals the environment from the receiving space 48 with the enlarged diameter portion 58.

[0026] Due to the above weld seam 72, the gas or medium space 12 has a resistance of <1*10 for helium. -8 mbar l / s(<1*10 -6 It is possible to achieve tightness with a leakage rate of 100 Pa l / s. In a corresponding embodiment, it is also possible to determine the pre-filling pressure in the accumulator housing 10 after filling and before welding by precise means, which therefore has no equivalent in the prior art.

Claims

1. A pressure accumulator comprising an accumulator housing (10), wherein a movable separating element (16) fluid-tightly separates a preferably gas-filled medium space (12) from a fluid space (14), and a monitoring device (28) is provided, the monitoring device (28) giving a visually perceptible indication when a fault occurs that impairs the sealing effect of the separating element (16), the monitoring device (28) communicating with the medium space (12) and having a viewing window (40) through which an indicator (42) whose optical properties change perceptibly when wetted with fluid can be observed, the monitoring device (28) having a screw plug (32) that can be screwed into a corresponding internal thread (44) of the accumulator housing (10), the screw plug (32) having the viewing window (40), the indicator (42) and a fluid-permeable blocking device (46), the blocking device (46) delimiting the viewing window (40) and forming an accommodation space (48) in the screw plug (32) for accommodating the indicator (42), the blocking device (46) spatially separating the accommodation space (48) from the interior of the medium space (12) of the accumulator housing (10), characterized in that it is a pressure accumulator.

2. The pressure accumulator according to claim 1, characterized in that the screw plug (32) is formed as a hollow screw and comprises a frustoconical receptacle (56) for accommodating the viewing window (40) at least in the region of the screw head (36).

3. The pressure accumulator according to claim 1 or 2, characterized in that the viewing window (40) is made of glass, preferably borosilicate glass, and is metallurgically bonded to the screw plug (32).

4. The pressure accumulator according to claim 1 or 2, characterized in that the glass of the viewing window (40) breaks when a preset target pressure threshold between the test pressure and the bursting pressure is exceeded, and breaks into extremely small fragments upon breaking.

5. The pressure accumulator according to claim 1 or 2, characterized in that the indicator (42) is freely movable within the accommodation space (48).

6. The frustum-shaped receptacle (56) having the viewing window (40) transitions to a ring groove-shaped enlarged diameter portion (58) within the screw plug (32) that is part of the accommodation space (48) of the indicator (42). The pressure accumulator according to claim 2, characterized in that.

7. The indicator (42) is composed of a fluid-permeable capsule (60) in which an indicator material (62) is accommodated. The pressure accumulator according to claim 1 or claim 2, characterized in that.

8. The shut-off device (46) is formed of a dome-shaped sieve structure or a membrane structure and is held at a predetermined position within the screw plug (32) using an insert ring (50). The pressure accumulator according to claim 1 or claim 2, characterized in that.

9. The accumulator housing (10) includes a pot-shaped recess (64) having an internal thread (44) on its inner peripheral surface. The pressure accumulator according to claim 1 or claim 2, characterized in that.

10. The engagement depth of the recess (64) is selected such that when the screw plug (32) is screwed in, an axial gap is formed between the free end face (68) of the screw plug (32) and the bottom (66) of the recess (64). The pressure accumulator according to claim 9, characterized in that the gap preferably serves to receive a sealing material.

11. A further sealing material is arranged at the transition portion (70) between the screw head (36) of the screw plug (32) and the adjacent upper side of the accumulator housing, and / or a peripheral weld line (72) is arranged. The pressure accumulator according to claim 1 or claim 2, characterized in that.

12. A screw plug, particularly a screw plug for the pressure accumulator according to claim 1 or claim 2, which is an integral component within a screw housing, the viewing window (40), the indicator (42), and a shut-off device (46) having fluid permeability and designed to hold the indicator (42) within the accommodation space (48) of the screw housing. A screw plug, characterized in that it comprises.

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