Hydraulic accumulator

Abstract

The invention relates to a hydraulic accumulator, especially a piston accumulator, comprising an accumulator housing (10) and at least one gas chamber (12) and a fluid chamber (14), these being separated from each other by a separating element (16). At least one of these chambers (12, 14) can be filled with a pressure medium or at least partially emptied of the same through at least one valve control unit (26) which has a switching valve (28, 30). The respective switching valve (28) is accommodated in a corresponding valve location (29), and can be moved in the direction of movement of the separating element (16) from an opening position into closing position and vice-versa. The aim of the invention is to avoid an expensive line network between the hydraulic accumulator and the valve control unit, so that sealing or leakage problems such as are common in a line network, never occur, To this end, the valve control unit (26) is accommodated in a valve block (24) which is independent from the housing (10), said valve block (24) has an additional valve location (31) for an additional switching valve (30) for performing another switching task, and the valve locations (29, 31) are configured essentially identically an(l are situated eccentrically in relation to the longitudinal axis (33) of the hydraulic accumulator for modular use of the switching valves (28, 30), which are configured as identical parts.

Description

[0001] The invention pertains to a hydraulic accumulator, especially a piston accumulator, with the features of the preamble of Claim 1.

[0002] One of the main purposes of hydraulic accumulators is, among other things, to accommodate certain volumes of pressurized fluids of a hydraulic system and to feed these volumes back to the system upon demand. Hydraulic accumulators of this type that are in common use include piston accumulators, bladder accumulators, and diaphragm accumulators, but also weight-loaded and spring-loaded accumulators. Hydraulic accumulators of this kind can be used to perform a variety of tasks, such as storing energy, damping shock, oscillation, and pulsation, recovering energy, compensating for volume flow, etc..

[0003] Valve control units that are commonly equipped with on-off or way valves to control the flow of fluid to and from the hydraulic accumulator are used to operate the hydraulic regulators and control them. In this connection the hydraulic accumulator is commonly connected to pipework by fluid lines that provide the fluid-carrying connection between the accumulator and the valve control unit. Drawbacks of the known solution, as embodied in a wide variety of designs that are readily available on the market, include sealing problems owing to the large number of connections between the hydraulic accumulator pipework and the valve control unit and also the added costs for the network of lines connecting to the fluid lines. Especially under cramped conditions, there are also problems with accommodating the large number of the above-mentioned components in a reasonable fashion and connecting them together in such a way that they can carry fluid. Since moreover different manufacturers produce the hydraulic accumulators, the pipework, and/or the valves of the valve control units, mating problems in particular arise on the spot where the installation work is actually done.

[0004] From DE-A-27 07 469 a hydraulic accumulator is known, especially in the form of a device for regulating pressure. The known hydraulic accumulator accomplishes the tasks of, on the one hand, keeping the pressure in the accumulator at a given level and, on the other, protecting the above-mentioned accumulator against any accidental overpressure. To accomplish this, the known hydraulic accumulator has a valve slider like a hollow sleeve located inside a valve recess that extends along the longitudinal axis of the hydraulic accumulator; said valve slider receives the high pressure at its middle and at one of its ends is subjected to the operating pressure that is to be regulated. At its other end, said valve slider rests against a support body on which an adjustable spring exerts a counteracting force. Since the surface area of the contact circle between the sleeve and the support body is smaller than the surface area of the cross-section of the sleeve itself, the displacements of the sleeve against the spring cause the inlet opening through which the high pressure enters to close like an on-off valve. The known valve arrangement is an integral part of the lower half of the housing of the accumulator, whereby said lower half can be screwed together with the upper half of the housing, thereby forming the housing of the hydraulic accumulator. With the known solution, the separating element consists of an elastic-rubber diaphragm that is equipped with a closing unit in the middle, so that the switching direction of the on-off valve coincides with the direction of motion of the separating element. If the on-off valve fails in the case of a design according to the known solution, for maintenance purposes the valve block that contains the on-off valve has to be removed together with the lower half of the housing or the appropriate replacement has to be made; this increases the production and maintenance costs in the case of a design according to the known solution. Although the valve control unit with the known on-off valve is designed to be large in terms of geometry, only one valve function can be performed in terms of triggering the separating element.

[0005] For a piston pressure accumulator, especially for drive-slip-controlled braking systems, DE-A-39 41 241 does propose an on-off valve in the form of a load valve, whereby, in order to save space, its direction of motion is arranged perpendicular to the direction of motion of a pressure accumulator piston, as well as to the direction of motion of a shaped part that surrounds it as a partition unit for the accumulator and this piston is placed above a monitoring switch as a motion sensor for the shaped part in a valve block of the valve control unit of the piston pressure accumulator; with this known arrangement, however, only a single switching task is accomplished and, in view of the fact that the on-off valve is installed in a transverse position, the valve control unit still requires a relatively large amount of room. Moreover, the transverse installation position makes it necessary to divert the fluid stream, which is undesirable from the standpoint of fluid mechanics.

[0006] From EP-A-0 816 142 and U.S. Pat. No. 5,342,080 hydraulic accumulators of this kind are known in accordance with the implementation of the features of the preamble of Claim 1. Thus, the known solutions ensure modular installation of the on-off valves, which are designed as identical parts, so that a number of switching functions can be performed with respect to a hydraulic accumulator despite the compact dimensions of the valve control unit. Thus, in particular, the one on-off valve can actuate the separating element, and the respective other on-off valve can be used for other purposes, for example, to control the gas volume in the gas chamber of the hydraulic accumulator. To the extent that the known solutions are used in overall devices, the respective other on-off valve can also perform other switching tasks relating to adjacent fluid-bearing units, for example, in the form of cooling pumps, hydraulic cylinder devices, etc..

[0007] Since the switching direction of the on-off valves runs parallel to the direction of motion of the separating element as well as in the longitudinal direction of the hydraulic accumulator, it is possible to control the flows of fluid in ways that are favorable from the standpoint of fluid mechanics without diverting the flows. Since the on-off valves are designed as identical parts, the valve control unit and also the hydraulic accumulator can be designed in a very cost-effective manner. If a certain on-off valve is not required for a certain use of the hydraulic accumulator, this valve can also be simply left out of the design and the recess can be closed off with a filler plug, or this valve can be used in other ways to guide the fluid. If the actual hydraulic accumulator or its valve control unit fails, these devices can be readily detached from one another and replaced with new components so that the overall function of the hydraulic system in the application of the hydraulic accumulator is not put at risk.

[0008] Since, with the solutions of this type, the on-off valves are connected to the corresponding hydraulic accumulator as detachable parts, however, sealing problems can arise, on the one hand, and, on the other, mechanical stress, for example, can cause the respective valve control unit to be separated or torn away from the accumulator housing.

[0009] In view of the relevant state of the art, the object of the invention is thus, while retaining the above-described advantages, to create a hydraulic accumulator that requires little overall installation space and allows the hydraulic accumulator to be securely connected to the on-off valves, which are designed as identical parts, while ensuring a secure seal. A hydraulic accumulator with the features of Claim 1 in its entirety accomplishes an object of this nature.

[0010] Because according to the characterizing part of Claim 1 the valve recesses are of essentially the same design, because the control block with its extension, in close contact with the inside circumference of the accumulator housing, extends into said housing, and because the accumulator housing rests with its one free end against a shoulder of the control block, where the extension originates, secure sealing of the connection between the accumulator housing and the control block extension. Moreover, the shoulder makes it possible to position the accumulator housing precisely with respect to the rest of the control block and to ensure that the accumulator housing is safely guided along the extension of the control block. Accidental detachment of the accumulator housing from the valve control unit is thus reliably prevented.

[0011] In another preferred embodiment of the hydraulic accumulator according to the invention, the control block forms the boundary for the fluid chamber by means of its extension, whereby the control block has at least one fluid channel that empties with its free end into the fluid chamber and is connected with its other free end to the on-off valve. Since the control unit makes a transition directly into the fluid chamber, the free paths for the pressure medium are kept short, thus ensuring fast reaction times for the hydraulic accumulator.

[0012] The dependent claims describe other favorable embodiments.

[0013] The hydraulic accumulator according to the invention is explained in greater detail below based on the drawing.

[0014] The single FIGURE, which is an outline and is not drawn to scale, shows, partly in section and partly in plan, a longitudinal view of the hydraulic accumulator.

[0015] The hydraulic accumulator according to the FIGURE is designed as a piston accumulator. This accumulator has an accumulator housing 10 with a gas chamber 12, located therein, and a fluid chamber 14. The gas chamber 12 is separated from the fluid chamber 14 by a separating element 16 in the form of a piston part that can be moved longitudinally along the inside circumference of the accumulator housing 10 so that the spatial relationship between the gas chamber 12 and the fluid chamber 14 is kept variable. In order to be able to store a large quantity of working gas in the gas chamber 12, the separating element 16 is designed as a hollow part and on the inside has a corresponding recess 18. In the direction facing toward the FIGURE, the gas chamber 12 is closed at the top by a cover part 20, which has a center hole 22, through which the working gas, for example, nitrogen gas, can be brought into the gas chamber 12. The corresponding center hole 22 is then sealed gas-tight by means of a closing valve or similar device (not shown), whereby the quantity of gas in the gas chamber 12 can also subsequently be checked and supplemented periodically via the closing valve.

[0016] At the opposite end of the accumulator housing 10 is the valve control unit, referred to overall as 26, which is in the form of a control block 24. The valve control unit 26 has two on-off valves, whereby the reference number of the first on-off valve is 28, and the number 30 refers to the second on-off valve. The corresponding valve control unit 26 is also an integral part of the accumulator housing 10, whereby for this purpose there is a control block 24 with a projection 32 which, in direct contact with the inside circumference of the accumulator housing 10, extends into said housing. Moreover, the accumulator housing 10 rests with its one free end 34 against a shoulder 36 of the control block 24, whereby extension 32 originates at said shoulder. Compared to the rest of the outside diameter of the control block 24, the extension 32 that extends into the accumulator housing is reduced in diameter in accordance with the decrease in size via the shoulder 36.

[0017] The hydraulic accumulator according to the invention is thus characterized by the fact that the valve control unit 26 is housed in a valve block 24 that is self-contained relative to the housing 10, the valve block 24 has another valve recess 31 for another on-off valve 30, which performs another switching task, and the valve recesses 29, 31 are designed essentially alike and are arranged off-center from the longitudinal axis 33 of the hydraulic accumulator to ensure the modular installation of the on-off valves 28, 30, which are designed as identical parts.

[0018] With the upper end of the extension 32, the control block 24 limits the fluid chamber 14 in the downward direction in the direction facing toward the FIGURE. The accumulator housing 10, the chambers 12 and 14, the cover part 20, the piston part 16, and the extension 32 are designed essentially as cylindrical components and extend along a common longitudinal axis 38 of the hydraulic accumulator. The control block 24 also has a fluid channel 40, which is arranged off-center from the longitudinal axis 38 and which empties with its one free end into the fluid chamber 14 and is connected with its other free end to the first on-off valve 28. Running transverse to the fluid channel 40, there is in the control block 24 a transverse connection 42 to which a fluid line, for example, as part of a hydraulic circuit, could be connected. The first on-off valve 28 is then connected between the transverse connection 42 and the fluid channel 40, whereby the fluid-carrying connection between the transverse connection 42 and the fluid channel 40 is open in the one switch position and is closed in the other switch position. Preferably the first on-off valve 28 is accordingly designed as a so-called 2/2-way valve. It would also be conceivable, however, to install other valves here, such as way-slider valves, valves with damping systems, etc., depending on the particular application.

[0019] Installed in the same position relative to the first on-off valve 28 is another second on-off valve 30 next to it, which in this case is also designed as a 2/2-way valve. The second on-off valve 30 has two lateral connections 44, 46 which, like the transverse connection 42, extend sideways radially out from the control block 24. The two lateral connections 44, 46 are in turn separated from one another by the switching parts of the second on-off valve 30. When the second on-off valve 30 is switched through, the lateral connections 44, 46 are connected together to carry fluid or are separated from one another with the valve in the blocking position. With the corresponding second on-off valve 30, it would then be possible, for example in an embodiment not shown here, to actuate of the entry and exit of the working gas in the gas chamber 12 to the extent that the connections 44, 46 are connected to the gas chamber 12 in such a way as to carry fluid via connection points in the cover part 20. In another embodiment, not shown here, it could also be possible for the second on-off valve 30 to actuate another assembly in the hydraulic circuit, for example, in the form of a hydraulic working cylinder or the like.

[0020] In the embodiment in question here, the on-off valves 28, 30 are designed as magnetic valves 48 that can be actuated electrically by connections 50. Since the above-mentioned magnetic valves 48 are part of the state of the art, it is not necessary to go into further detail regarding them.

[0021] The hydraulic accumulator according to the invention provides a complete solution that allows a compact design. In the embodiment shown, the first and second on-off valves 28, 30 are axially arranged essentially parallel to the longitudinal axis 38 of the hydraulic accumulator in the control block 24. Other installation positions transverse to the longitudinal axis would, however, also be possible, especially in the radial direction. The fact that the accumulator housing 10 is in direct contact with the control block 24 means that leakage is avoided and expensive, labor-intensive pipework is not necessary. Since the control block 24 with its extension 32 extends directly into the fluid chamber 14 of the accumulator housing 10, in particular the first on-off valve 28 is located right next to the fluid chamber 14 and is separated only by the fluid channel 40, which is kept short by design, so that very short activation times can be expected for the hydraulic accumulator.

Claims

1. A hydraulic accumulator, especially a piston accumulator, with an accumulator housing (10) and at least one gas chamber (12), located therein, and a fluid chamber (14), which are separated from one another by a separating element (16), whereby at least one of said chambers (12, 14) can be filled with a pressure medium via a valve control unit (26) that has at least one on-off valve (28, 30) and said medium can be at least partially drained therefrom via said valve control unit and whereby the corresponding on-off valve (28) is housed in an appropriate valve recess (29), whereby said on-off valve can move from an open position to a closed position in the direction of motion of the separating element (16) and vice versa, characterized by the fact that the valve control unit (26) is housed in a valve block (24) that is self-contained relative to the housing (10), the valve block (24) has another valve recess (31) for another on-off valve (30), which performs another switching task, and the valve recesses (29, 31) are designed essentially alike and are arranged off-center from the longitudinal axis (33) of the hydraulic accumulator to ensure modular installation of the on-off valves (28, 30), which are designed as identical parts.

2. The hydraulic accumulator as claimed in claim 1, wherein the control block (24) with an extension (32), in direct contact with the inside circumference of the accumulator housing (10), extends into said housing and the accumulator housing (10) rests with its one free end (34) against a shoulder (36) of the control block (24), where the extension (32) originates.

3. The hydraulic accumulator as claimed in claim 2, wherein with its extension (32) the control block (24) limits the fluid chamber (14) and the control block (24) has at least one fluid channel (40), which with its one free end empties into the fluid chamber (14) and with its other free end is connected to the on-off valve (28).

4. The hydraulic accumulator as claimed in one of claims 1-3, wherein the other on-off valve (30) is connected to the gas chamber (12) and actuates the entry or exit of the working gas or takes over the function of fluid control for another assembly.

5. The hydraulic accumulator claimed in one of claims 1-4, wherein the on-off valves (28, 30) are designed as 2/2-way valves.

6. The hydraulic accumulator as claimed in claim 5, wherein the 2-2-way valves are designed as magnetic valves (48) and can be activated electrically.

7. The hydraulic accumulator as claimed in one of claims 1-6, wherein said accumulator is designed as a piston accumulator with a separating piston as a separating element (16).

8. The hydraulic accumulator as claimed in one of claims 1-7, wherein the accumulator housing (10) and the control block (24) are designed essentially as cylindrical components.

9. The hydraulic accumulator as claimed in one of claims 1-8, wherein the on-off valves (28, 30) can be switched regardless of the positions of the separating element (16), whereby said positions are determined by the pressure conditions.