Device

Abstract

The invention relates to a device, in particular for volume compensation in fluid circuits, at least consisting of a device housing (10) and a compensating element (12) which is movably guided therein, that can be acted on by a fluid pressure (p) and is supported on an energy storage device (14), characterised in that the device housing (10) has at least two housing parts (16, 18), which are arranged one behind the other when viewed along the longitudinal axis (20) of the device housing (10), in that the adjacent housing parts (16, 18) differ in their free cross-sectional areas, and in that the transition from one housing part (16) to the subsequent, adjacent housing part (18) is in the form of a step (22).

Description

[0001] device

[0002] The invention relates to a device, in particular for volume compensation in fluid circuits, comprising at least a device housing and a compensating element movably guided therein, which is supported by a fluid pressure and supported on an energy accumulator. EP 3 191 717 B1 discloses a device for pressure relief on hydraulic lines, in particular in connecting lines having coupling points between attachments having hydraulically actuated actuators and the implements supplying them. The device comprises a control block connected to the line to be relieved, which contains a releasable check valve as a relief valve, a pressure accumulator that receives a relief volume when the check valve is unlocked, and a manually movable actuating member for unlocking the check valve, which is movably arranged on the device housing of the pressure accumulator.The pressure accumulator is designed as a spring accumulator, which has an axially movable accumulator piston as a compensating element, which is loaded on its side facing away from the fluid chamber by a compression spring as an energy accumulator and is penetrated by a coaxial actuating rod, the inner end of which extends through a fluid inlet of the device housing to the closing body of the check valve. At the outer end of the actuating rod, which projects beyond the outer end of the accumulator's device housing, an actuating button for manually displacing the actuating rod is also attached. In the known solution, the device housing is formed from a pot-like, one-piece housing part with a hollow cylindrical shell and an inner cross-sectional area whose diameter is constant.

[0003] Such spring accumulators offer a maintenance-free alternative to gas-filled pressure accumulators, as refilling on the gas side is not required. Another advantage is their temperature-independent characteristic curve, which allows them to cover a wide temperature range without affecting the pressure-volume curve, as is the case with hydropneumatic accumulators.

[0004] Based on this prior art, the object of the invention is to create a device that further improves the known solutions, in particular increases their possible applications.

[0005] A device having the features of patent claim 1 in its entirety solves this problem.

[0006] Because, according to the characterizing part of patent claim 1, the device housing has at least two housing parts that are arranged one behind the other along the longitudinal axis of the device housing, because the adjacent housing parts differ in terms of their free cross-sectional areas, and because the transition from one housing part to the next, adjacent housing part takes the form of a step, the device housing can be adapted in a practical manner to on-site installation conditions within a wide frame. In particular, the aforementioned adaptation to the housing parts of the device housing allows the device to be accommodated in a space-saving manner in cramped installation spaces. Despite the change in cross-sectional area and the associated different housing part design, an overall rigid housing construction is achieved that can easily withstand even high actuation forces.

[0007] The device according to the invention can preferably be used for volume compensation in closed fluid circuits, thus compensating for volume changes over temperature. Thus, the device can be used in both high-pressure and low-pressure ranges.

[0008] The step in question preferably consists of an annular surface arranged concentrically to the longitudinal axis of the device housing, which creates a continuous transition between two adjacent housing parts. The step preferably consists of a truncated cone, whose notional base surface transitions into the housing part with the larger free cross-sectional area and whose notional top surface transitions into the adjacent housing part with the smaller free cross-sectional area. This creates a harmonious transition between the different housing parts of the device housing, so that any stress peaks that may occur in this material area can be easily compensated, and a load introduction via the step is distributed equally toward both adjacent housing parts.

[0009] In a preferred embodiment of the device according to the invention, it is provided that the adjacent housing parts are formed from hollow cylinders with circular cross-sectional areas, and that each hollow cylinder has a cross-sectional area whose diameter differs from the diameter of the other cross-sectional area. Preferably, it is further provided that the housing part with the larger free cross-sectional area guides the compensating element, and the adjacent housing part with the smaller cross-sectional area accommodates at least part of the energy storage device. In this way, hydraulic charging of the device can take place via an outwardly open side in the device housing, without being impaired by the installation of the energy storage device in the device housing.

[0010] In a further preferred embodiment of the device according to the invention, the energy storage device is formed from at least one, preferably two, compression springs, the spring wire of which extends in a spring chamber from the compensating element to a closure in the device housing. In particular, the use of two spiral compression springs allows for a reduction in the length of the device housing compared to a solution with only one spring and the same spring force of two springs.

[0011] Preferably, an outer spring wire surrounds the inner spring wire in a concentric arrangement with the longitudinal axis of the device housing and preferably has greater spring stiffness than the inner spring wire. Preferably, at least a portion of the outer spring wire can be guided within the housing part with the smaller free cross-sectional area and thus supported against outward buckling, which benefits the overall guidance of the entire spring arrangement in the device housing. In this way, the outer spring also additionally supports the inner spring.

[0012] For a particularly rigid construction of the spring arrangement, the coil pitches of the two concentrically arranged compression springs, which are preferably cylindrical, are different from one another. In a particularly preferred embodiment of the device according to the invention, a guide is arranged within the device housing, which extends into the spring chamber and provides support for at least some of the compression springs during their operation. At low pressures and relatively large volume displacements, correspondingly long springs must be used, which generally tend to buckle. Thanks to the guide, which at least partially guides the internal spring wire, this buckling is effectively counteracted.

[0013] The guide is preferably formed from a tubular body, the interior of which is in media communication with the spring chamber, so that hindrances during operation caused by any trapped air volumes are avoided. The tubular body is particularly preferably formed from a telescopic tube which can be returned from a retracted position to its extended starting position by means of a return device, in particular in the form of a magnet, by means of the preferably piston-shaped compensating element. Thanks to the telescopic guide, effective support for the respective compression spring on its respective inner side can be achieved over a very long travel path of the piston-shaped compensating element. When a corresponding loading stroke is reached, the piston-shaped compensating element can displace a telescopic outer tube relative to a telescopic inner tube within the device housing.The aforementioned telescopic design also enables the stabilization of the storage characteristic curve and reduces friction for the piston-shaped compensating element. The tendency of the compensating element to tip is also reduced, which is otherwise regularly caused by the buckling of slender springs. However, the device solution according to the invention effectively counteracts precisely this risk of buckling. In a further preferred embodiment of the device according to the invention, it is provided that the tubular body, in particular in the form of the telescopic tube, terminates on the side of the lid-like closure into a pressure compensation element that passes through the lid-like closure. The device housing, with its individual housing parts, terminates at one of its free end faces into a housing base, which forms the closure of the device housing.The pressure compensation element is inserted into this cover-like closure, through which ambient air can be introduced into or expelled from the interior of the device housing, depending on the direction of travel of the compensation element. Due to the pressure compensation element, trapped air cannot be compressed inside the device housing, i.e., the spring chamber, thus enabling unhindered operation of the device at all times. This creates a type of breathing system, particularly in the form of a spring-loaded device.

[0014] The hollow cylindrical housing parts connected to one another via the step preferably have the same wall thickness. The device housing is particularly preferably constructed as a single piece with its individual housing parts and can preferably be obtained in a single process step using a cold extrusion process. Thus, the individual cylindrical outer surfaces of the housing parts connected to one another via the step form a single-piece cold extrusion, preferably together with the lid-like closure.

[0015] In the following, the device according to the invention is explained in more detail with reference to exemplary embodiments shown in the drawings. The drawings are schematic and not to scale.

[0016] Figures 1, 2 show two different embodiments of the device according to the invention in the form of a simplified longitudinal section and in an initial state.

[0017] The device shown in Figure 1 has a device housing 10 with a compensating element 12 which is guided longitudinally therein and which, as viewed in the direction of Figure 1, can be acted upon by a fluid pressure p on the left and is supported on an energy storage device 14 on the right thereof.

[0018] The device housing 10 has two housing parts 16, 18, which are arranged one behind the other along the longitudinal axis 20 of the device housing 10. The adjacent housing parts 16, 18 differ in their free cross-sectional areas, with the transition from one housing part 16 to the next adjacent housing part 18 taking the form of a step 22.

[0019] The step 22 consists of an annular surface 24 arranged concentrically to the longitudinal axis 20 of the device housing 10, which creates a continuous transition between the two adjacent housing parts 16, 18. In particular, the step 22 consists of a truncated cone whose notional, circular base surface 26, represented by dashed lines, merges into the housing part 16 with the larger free cross-sectional area. The notional top surface 28 of the truncated cone, again represented by dashed lines, opens into the adjacent housing part 18 with the smaller free cross-sectional area. Like the base surface 26, the top surface 28 also has a circular cross-section.

[0020] The adjacent housing parts 16, 18 consist of hollow cylinders with circular cross-sectional areas, each hollow cylinder having a cross-sectional area whose diameter differs from the diameter of the other cross-sectional area. As can also be seen from Figure 1, the housing part 16 with the larger free cross-sectional area guides the compensating element 12, whereas the adjacent housing part 18, which adjoins the step 22 and has a smaller cross-sectional area, accommodates at least part of the energy storage device 14.

[0021] The compensating element 12 consists of a cylindrical hollow piston, which has the usual guide and sealing devices on its outer circumference, whereby only the associated annular grooves 30 are shown in Figure 1 for the sake of simplicity. The piston-like compensating element 12 slides with its outer circumference along the cylindrical inner circumferential surface of the first housing part 16 over the corresponding guide and sealing devices (not shown). In this respect, the step 22, which tapers conically toward the free end of the device housing 10, which is opposite the compensating element 12, forms a possible stop for the compensating element 12.Furthermore, the compensating element 12 is in its unactuated initial position according to the illustration in Figure 1 and is supported on its side facing the fluid pressure p along the outer circumference of its piston head 32 on a snap ring 34 which is received transversely to the orientation of the longitudinal axis 20 in an associated inner circumferential groove 36 of the first housing part 16.

[0022] The energy storage device 14 in question consists of two compression springs 38, 40, whose spring wire extends in a spring chamber 42 from the compensating element 12 to a lid-like closure 44 in the device housing 10. The outer spring wire of the second compression spring 40 encompasses the inner spring wire of the first compression spring 38 in a concentric arrangement with the longitudinal axis 20, and the second compression spring 40 preferably has a greater spring stiffness than the first compression spring 38 with its inner spring wire. The coil pitches of the two concentrically arranged compression springs 38, 40 differ from one another and, in particular, as viewed in the direction of Figure 1, the coil pitch of the first compression spring 38 is oriented to the right and that of the second compression spring 40 to the left. Furthermore, the compression springs 38, 40, which are designed as helical compression springs, are essentially cylindrical.Both compression springs 38, 40 are supported with their free ends on the one hand on the inside of the piston crown 32 and on the other hand on the inside of the cover-shaped end 44.

[0023] As can be further seen from Figure 1, a guide 46 is arranged within the device housing 10, running concentrically to the longitudinal axis 20. Said guide 46 projects into the spring chamber 42 and provides support for at least some of the compression springs, in particular for the innermost compression spring 38 during its operation. In this respect, the guide 46 at least partially guides the inner spring wire of the compression spring 38. The guide 46 is formed from a tubular body, the interior 48 of which is in media connection with the spring chamber 42. For this purpose, the tubular body has individual openings 50 in the tubular body wall, which are divided into three groups and extend diametrically around the longitudinal axis 20. Depending on the size of the respective opening 50, these can also be designed in the manner of apertures and can also support the intended damping.

[0024] In the embodiment according to Figure 1, the tubular body is formed from a telescopic tube 52 with a telescopic outer tube 54 and a telescopic inner tube 56. While the telescopic inner tube 56 is fixedly secured at one of its free ends to the cover-like closure 44, the telescopic outer tube 54 is guided longitudinally along the outer circumference of the telescopic inner tube 56. To this extent, the two tubes 54, 56 are captively engaged with one another via correspondingly designed stops 58. Furthermore, a sealing ring 60 is provided in the connection area 44 and on the telescopic inner tube 56, which seals the spring chamber 42 and the interior 48 of the telescopic tube 52 from the environment. The telescopic outer tube 54 has a ring magnet 62 on its free end facing away from the closure 44 as part of a reset device 64.Another part of the respective return device 64 is a cylindrical steel body 66, which is preferably an integral part of the piston crown 32 of the compensating element 12. The ring magnet 62 exposes a central opening 68, through which the interior 48 of the telescopic tube 52 communicates with the spring chamber 42. Instead of a steel body 66, a comparable body can also be made of aluminum or plastic, which then has a corresponding magnet or steel part on its end face, for example in the form of a plate.

[0025] If a fluid pressure p exerts a greater force on the outer piston surface of the compensating element 12 than the spring force of the two compression springs 38, 40, the piston-like compensating element 12 moves from its left-hand starting position shown in Figure 1 into a right-hand travel movement, with the spring force increasing as a result of the compression of the two compression springs 38, 40. At maximum fluid pressure p, the free end face of the steel body 66 comes into contact with the free end face of the telescopic outer tube 54 and takes the latter accordingly to the right. The telescopic outer tube 54 slides onto the telescopic inner tube 56 up to a maximum possible stop position, at which the telescopic outer tube 54 comes into contact with the cover-like closure 44.

[0026] As a rule, however, the spring counterforce will already be sufficient at an earlier point in time to effectively counteract the fluid pressure p, so that the telescopic outer tube 54 does not necessarily reach its stop position and / or the compensating element 12 does not come into contact with the step 22. If the fluid pressure p decreases completely again, the two compression springs 38, 40 relax and the piston-like compensating element 12 again reaches its left stop position with the snap ring 34 arranged stationary in the first housing part 16. Intermediate positions for the compensating element 12 are possible, depending on the force equilibrium between the fluid pressure p and the spring pressure. During the return movement, the steel body 66 takes the ring magnet 62 with it in such a way that the telescopic tube 52 with its two tubes 54, 56 can again assume its initial position shown in Figure 1.For the return movement in question, it is not absolutely necessary for the steel body 66 to come into contact with the ring magnet 62; rather, the magnetic force must be sufficient to carry out the return movement in question, whereby in any case the frictional force of the outer tube 54 on the outer circumferential side of the inner tube 56 must be overcome.

[0027] As can also be seen from Figure 1, the outer compression spring 40 is supported outwardly over the inner circumference of the second housing part 18, which has a reduced diameter, so that outward buckling in this area is not possible. Furthermore, inward buckling of the first compression spring 38 is not possible insofar as the spring wire of the inner compression spring 38 can be supported on the outer circumference of the telescopic outer tube 54 in each of its travel positions. Further support of the two compression springs 38, 40 is provided by their concentric arrangement, in which spring wire parts of the two compression springs 38, 40 may come into contact with one another under load.

[0028] The device further comprises a pressure compensation element 70, which passes through the lid-like closure 44 and opens into the environment on one side and into the interior 48 of the stationary telescopic tube 52 on the other side. Thanks to the pressure compensation element 70, a type of breathing system is achieved, particularly in the form of a spring-loaded device, and depending on the direction of travel of the compensation element 12, ambient air can thus be introduced into or expelled from the interior of the device housing 10. The pressure compensation element 70 preferably comprises a membrane (not shown) to prevent the penetration of contamination, such as water or dirt.In this way, an exchange takes place between the ambient air and the interior of the device housing 10, in particular in the form of the spring chamber 42, without compressing the air enclosed there, so that a variable pressure setting is essentially determined by the prevailing fluid pressure p and the spring tension of the two compression springs 38, 40. It is understood that with a correspondingly stiff spring, the device solution according to the invention can also manage with only one compression spring if necessary.

[0029] The hollow cylindrical housing parts 16, 18 connected to one another via the step 22 have the same thin wall thickness, so that the device housing 10 with its housing parts 16, 18 is formed in one piece and is preferably obtained by means of a cold extrusion process. Depending on the pressing process used, the respective wall thicknesses can also be thicker or of different thicknesses. For weight reasons alone, a thin-walled design is preferable. In this respect, the device housing 10 with its bottom end part 44 can be made of a suitable steel material or, preferably, aluminum. Since the compensating element 12 is secured to the outside by the snap ring 34, an oil-side cover of the device housing 10 can be omitted.If the spring accumulator presented, the device housing 10 of which guides Euft and is used in particular for volume compensation in closed circuits at low pressures, a large number of components, in particular in the form of the guide 46, can be made of plastic.

[0030] Furthermore, an external thread 72 is provided on the bottom side of the device housing 10, adjacent to the snap ring 34, on the outer circumference, so that, in a type of cartridge design, the device as a whole can be screwed into a housing block (not shown), which has at least one fluid guide that carries the fluid pressure p. The relevant fluid pressure p is regularly generated via a fluid, for example in the form of a hydraulic medium, in a fluid circuit. Overall, the device solution according to Figure 1 achieves continuous, radial spring guidance for the respective compression spring 38, 40. The design of the device housing 10 as a cold-formed part allows for reliable absorption of the actuating forces occurring during operation, caused by the fluid pressure p and the spring force of the respective compression spring 38, 40.In the area of ​​the external thread 72, a further sealing ring 74 is provided, which, when the device housing 10 is screwed into a housing block or the like, provides a secure seal between the interior of the block and the environment.

[0031] A further exemplary embodiment according to Figure 2 is described below, which will only be explained insofar as it differs significantly from the embodiment according to Figure 1. Insofar as individual components according to Figure 1 are used in the embodiment according to Figure 2, the same reference numerals are used for these as in Figure 1, and the statements made in this regard also apply to the solution according to Figure 2. In the embodiment according to Figure 2, instead of a telescopic tube 52, a guide 46 with a single tubular body is used, on the outside of which the spring wire of the inner compression spring 38 can in turn be supported.The tubular guide 46 in question is clipped to the drive element, for example in the form of a cylindrical steel body 66, via a further snap ring 76, and is otherwise open at its opposite free end, so that the interior 48 of the guide 46 opens into the spring chamber 42. Furthermore, in this embodiment, the pressure compensation element 70 opens onto the inside of the device housing 10 and into the spring chamber 42. The hollow cylindrical guide 46 is synchronously driven by the compensation element 12 during a movement from left to right until the free end of the guide 46 comes into contact with the wall-like end 44, which in this respect forms a stable stop. In the direction of this stop, the inner circumference of the guide 46 encompasses parts of the outer circumference of the pressure compensation element 70, which allows improved guidance in the stop area.To relieve the load on the stage 22 in the embodiment according to Figure 1, it can be provided that the telescope reaches its stop before the piston-shaped end part 12 comes into contact with the stage 22. In this way, a relief of the storage housing 10 during operation is achieved in both embodiments.

Claims

Patent claims 1. Device, in particular for volume compensation in fluid circuits, at least consisting of a device housing (10) and a compensating element (12) which is movably guided therein and which is supported on an energy store (14) by means of a fluid pressure (p), characterized in that the device housing (10) has at least two housing parts (16, 18) which are arranged one behind the other as seen in the longitudinal axis (20) of the device housing (10), that the adjacent housing parts (16, 18) differ in terms of their free cross-sectional areas, and that the transition from one housing part (16) to the next, adjacent housing part (18) takes the form of a step (22).

2. Device according to claim 1, characterized in that the step (22) consists of an annular surface (24) arranged concentrically to the longitudinal axis (20) of the device housing (10), which continuously creates a transition between two adjacent housing parts (16, 18).

3. Device according to claim 1 or 2, characterized in that the step (22) consists of a truncated cone, the fictitious base surface (26) of which merges into the housing part (16) with the larger free cross-sectional area and the fictitious cover surface (28) of which merges into the adjacent housing part (18) with the smaller free cross-sectional area.

4. Device according to one of the preceding claims, characterized in that the mutually adjacent housing parts (16, 18) are formed from hollow cylinders with circular cross-sectional areas and that each hollow cylinder has a cross-sectional area whose diameter differs from the diameter of the other cross-sectional area.

5. Device according to one of the preceding claims, characterized in that the housing part (16) with the larger free cross-sectional area guides the compensating element (12) and the adjacent housing part (18) with the smaller cross-sectional area accommodates at least part of the energy storage device (14).

6. Device according to one of the preceding claims, characterized in that the energy storage device (14) is formed from at least one, preferably two, compression springs (38, 40), the spring wire of which extends in a spring chamber (42) from the compensating element (12) to a termination (44) in the device housing (10).

7. Device according to one of the preceding claims, characterized in that an outer spring wire surrounds the inner spring wire in a concentric arrangement to the longitudinal axis (20) of the device housing (10) and preferably has a greater spring stiffness than the inner spring wire.

8. Device according to one of the preceding claims, characterized in that the winding pitches of the two concentrically arranged compression springs (38, 40) are different from each other, which are preferably cylindrical.

9. Device according to one of the preceding claims, characterized in that a guide (46) is arranged within the device housing (10) which projects into the spring chamber (42) at least for some of the compression springs (38) which provide support during operation.

10. Device according to one of the preceding claims, characterized in that the guide (46) at least partially guides the inner spring wire. 1 1 .Device according to one of the preceding claims, characterized in that the guide (46) is formed from a tubular body, the interior (48) of which is in media connection with the spring chamber (42).

12. Device according to one of the preceding claims, characterized in that the tubular body is formed from a telescopic tube (52) which can be reset by means of a reset device (64), in particular in the form of a magnet (62), from a retracted position by means of the preferably piston-shaped compensating element (12) into its extended starting position.

13. Device according to one of the preceding claims, characterized in that the tubular body, in particular in the form of the telescopic tube (52), opens on the side of the lid-like closure (44) into a pressure compensation element (70) which passes through the lid-like closure (44).

14. Device according to one of the preceding claims, characterized in that in the manner of a breathing system, in particular in the form of a spring accumulator, ambient air can be introduced into or removed from the interior of the device housing (10) by means of the pressure compensation element (70) depending on the direction of travel of the compensation element (12).

15. Device according to one of the preceding claims, characterized in that the hollow cylindrical housing parts (16, 18) connected to one another via the step (22) have the same wall thickness.

16. Device according to one of the preceding claims, characterized in that the device housing (10) with its housing parts (16, 18) is formed in one piece and is preferably obtained by means of a cold extrusion process.

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