Cylinder assembly

Abstract

Cylinder assembly, actuated by pressure medium, consisting of a piston rod, sealed and guided in a first cylinder end piece as cylinder head - a piston rigidly connected to the piston rod, sliding tightly in a cylinder tube, a second cylinder end piece as cylinder base and a first pressure port (A) in the cylinder base (3) for supplying pressure medium to the piston chamber as well as a jacket tube (5) encompassing the cylinder tube (4) at a distance (22), characterized in that the pressure medium supply to the piston rod chamber (24) is provided via a second pressure port (B) in the jacket tube, the angular position of which is adjustable relative to the first pressure port (A).

Description

[0001] The invention relates to a pressure-medium-operated cylinder assembly according to the preamble of patent claim 1.

[0002] Pressure-operated cylinders are used throughout mechanical engineering wherever the movement of machine parts is required for work or production processes that require force. Such cylinders can be single-acting or double-acting. Single-acting cylinders require one pressure connection, while double-acting cylinders require two pressure connections. A detailed description of the state of the art for hydraulic cylinders can be found in the textbook "ÖLHYDRAULIK" (OIL HYDRAULIK), by Dietmar and Franz Findeisen, 4th edition 1994, pages 430-439. As will become apparent from the later course of the description of the invention, the description of the state of the art for double-acting cylinders is sufficient. Double-acting cylinders consist of the essential components of the cylinder barrel, piston, piston rod, cylinder head, and cylinder base.The design of the connection between piston rod and piston, unless integral, differs little in principle and is not so decisive for the overall cylinder design and, above all, not for the installation situation during intended use in work machines. In contrast, very different designs have been established for the types of connection between the cylinder barrel and the two end pieces, the cylinder head and cylinder base. In the so-called differential cylinder, the "cylinder base" refers to the closure piece opposite the piston or the entire piston surface, while the "cylinder head" refers to the closure piece located at the other end of the cylinder, which has a through-bore with a suitable seal for the piston rod.

[0003] In the tie rod cylinder design, the two end pieces are fixed centrally to the cylinder tube using suitable seal and groove combinations and are axially clamped using long screws, the so-called tie rods. The four tie rods are inserted through the holes in the corners of the preferably square end pieces. Both end pieces each have a pressure connection for the supply or removal of pressure medium for movement, usually of the piston with the piston rod, in order to generate a desired working movement. The pressure connections, often connected to high-pressure hoses, are therefore located opposite each other, with a pressure connection at each end of the cylinder assembly in the respective end piece. It is common practice to designate the connections A and B to enable identification in circuit diagrams, with A denoting the connection on the cylinder base and B the connection on the cylinder head.As can be seen from the design of a tie rod cylinder, ports A or B can be mounted rotated by 90°, 180°, or 270° relative to each other. This does not change the total cylinder stroke.

[0004] Another cylinder design is called a round cylinder, where the connection between the cylinder tube and end pieces is made in a variety of ways using internal or external threads on the cylinder tubes. Here, a distinction is again made between screw-in and screw-on versions, where the cylinder tube with its internal or external thread is screwed directly into or onto the external or internal thread of the end piece. The pressure ports A and B are also located at the assigned end in the respective end pieces of the cylinder assembly, in the cylinder head or cylinder base. With screw connections on one or both sides with screwing in up to the axial stop of the threaded parts, the angular position to each other is undefined unless special measures are taken. In order to achieve a desired angular position to each other, for example,the screw connection can be turned accordingly, but this changes the overall stroke due to the thread pitch, so that any resulting stroke tolerances must be taken into account in the further design of the driven machine, wherever possible. Also problematic is ensuring the seal between the cylinder barrel and the end piece, as well as any necessary anti-twist protection. Another measure is individual adaptation by reworking when assembling the individual parts to the cylinder assembly in order to achieve the desired position of connections A and B. This is of course very cost-intensive and not suitable for efficient series production. Any correction that may be necessary on site during assembly of the driven machine is then no longer possible at a reasonable cost.Solutions with end pieces welded to the cylinder barrel, with connections A and B in the welded parts, avoid the problem described above, whereby a locking ring with the rod seal is usually screwed into the cylinder head. With this solution too, connections A and B are each located at the corresponding end of the cylinder assembly, with a corresponding distance depending on the cylinder length and a predetermined angular position, and can no longer be changed. In a further design, with cylinder barrels with an external thread, the end pieces are designed with a centring shoulder for the cylinder barrel and an external flange surface with a number of screw-in threads arranged in a circle around the outside of the cylinder barrel as the flange surface. A threaded ring is also screwed onto the cylinder barrel thread and has the counter flange surface and the same symmetrical pitch and number of holes for the so-called.A multi-screw connection allows the end pieces to be clamped to the cylinder barrel with several individual screws. Depending on the design, the angular position of ports A and B relative to each other is possible within the scope of the screw pitch. However, they are also located at a large distance from each other at the respective ends of the cylinder assembly. Other double-acting cylinders are so-called double-acting or double-rod cylinders with cylinder heads on both sides and the port designations B1 or B2 in the cylinder heads. The problems of the cylinder barrel-end piece connection are the same and therefore need not be discussed further.

[0005] DE 10 2005 061 730 A1 proposes a cylinder design consisting of several cylinder tubes. The outer cylinder tube is referred to as the cylinder housing, and the inner one, in which the actual piston slides, is referred to as the center sleeve. Such a cylinder design can also be generally referred to as a "double-tube cylinder." The actual piston rod also consists of several tubular components, which is justified by the task and special feature of this proposal and represents its own state of the art. Essential within the scope of the invention is the arrangement of the pressure ports A and B in this "double-tube cylinder." Both pressure ports are arranged in the so-called distributor block - usually referred to as the cylinder base - and are designated as inlet and supply line, respectively. They are thus definitively fixed in a completed cylinder assembly and their position relative to one another can no longer be changed.

[0006] DE 197 55 283 A1 shows a double-acting pressure cylinder consisting of a cylinder barrel, a piston, a piston rod, a two-part cylinder chamber, and two guide rings acting as closure parts, which can also be referred to as the cylinder head and cylinder base, respectively. The pressure ports A and B are located opposite each other at the respective ends of the cylinder assembly, and their position relative to each other is fixed and cannot be changed. The double-acting cylinder is inserted through a tubular sleeve; this sleeve serves solely to mechanically secure the cylinder assembly within its operating range.

[0007] With increasing demands from machine manufacturers and operators regarding compactness and expanded functionality within the same installation space as possible, especially in mobile machines, the variety of existing cylinder designs presented here is insufficient to achieve further, decisive progress. Disadvantages and difficulties for new, innovative hydraulic drive arrangements are the largely rigid assignments of ports A and B, or the stroke changes caused by twisting threaded connections with the resulting additional problems, as well as the spatially distant spacing of ports A and B depending on the cylinder length.The oscillation of the entire cylinder due to a double-joint bearing between the cylinder base and the piston rod end requires high-pressure hose feeds, which, in turn, are subjected to increasing stress with increasing oscillation amplitude and thus have an additional lifespan limitation. This means that the closer the cylinder's hydraulic connection is to the swivel joint, usually the cylinder base, the lower the relative movements acting on the hose and thus the additional stress.

[0008] In view of the presented state of the art, it is an object of the present invention to design a double-acting cylinder assembly in such a way that the described disadvantages are overcome and the installation position as well as the assembly of the pressure connections can be simplified and adapted to the local conditions of the working machine during installation.

[0009] This object is achieved according to the invention in that the pressure medium supply to the piston rod chamber is provided via a second pressure connection in the rotatable jacket tube. This allows the arrangement of the pressure connections relative to one another within the cylinder assembly to be freely selected.

[0010] Advantageous further developments of the invention emerge from the subclaims.

[0011] This invention eliminates the disadvantages described above for prior art pressure-operated working cylinders and enables significantly simplified assembly and adaptation of the pressure connections of a cylinder assembly to the local conditions during installation in work machines. The additional loads acting on the high-pressure hoses due to relative movements are reduced, and stress-free hose installation is achieved through continuous angle adjustment of the jacket pipe connection. Furthermore, complex adjustment work during assembly is eliminated, resulting in corresponding savings in assembly costs. The total cylinder stroke remains unchanged, which results in a simpler design of the work machine and also reduces these production costs.

[0012] Further advantages and embodiments of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further listed features can be used individually or in combination in any desired manner. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention.

[0013] An embodiment of the invention is explained in more detail below with reference to the drawings.

[0014] They show: Fig. : Sectional view of a first embodiment of a differential cylinder with the piston rod in the retracted position. Fig. : Alternative embodiments of detail X from Fig. .

[0015] Fig. shows the cylinder arrangement 1 according to the invention, essentially consisting of the cylinder head 2, the cylinder base housing 3, the cylinder tube 4, the jacket tube 5, the piston 6 and the piston rod 7. The cylinder head 2 is equipped on its inner bore opposite the outer diameter of the piston rod 7 with a conventional guide-seal pair consisting of a guide ring 8, sealing ring 9 and scraper ring 10. Furthermore, the cylinder head 2 is firmly screwed to the jacket tube 5 by means of the threaded connection 11 up to the common, end-face stop 12. An inner centering seat 13 on the cylinder head 2 receives the cylinder tube 4 at its inner diameter 14, centrally to the inner bore in the cylinder head 2. On the opposite cylinder side, the cylinder tube 4 is inserted into a first, inner centering seat 15 in the cylinder base housing 3. A second, larger inner centering seat 16 receives the jacket tube 5 at its inner diameter 17.The pressure connection A and the channel 18 in the cylinder base housing 3 provide an inflow or outflow connection for the working pressure medium to / from the piston chamber 19. The pressure connection piece 20 on the jacket tube 5, which is welded on as an example in the illustration, forms the second pressure connection B required for a double-acting cylinder and leads via the bore 21 into the intermediate space 22 formed by the jacket tube inner diameter 17 and the outer diameter of the cylinder tube 4. The annular interior space 22 has a hydraulic connection via the openings 23 to the annular working chamber, the piston ring chamber 24 and to the pressurization of the piston ring surface 25. Piston 6 and piston rod 7 can be one piece or are firmly screwed together in the usual way. The piston 6 is guided and sealed to the cylinder tube inner diameter 14 with a conventional guide and sealing ring combination 26.The cylinder end pieces also have static seals 27 and 28 on the cylinder base housing 3 for internal sealing against the cylinder tube 4 and the outer casing 5, and 29 on the cylinder head 2 for external sealing against the outer casing 5. The positive and non-positive connection between the casing 5 and the cylinder base housing 3 is formed by the coupling arrangement 30. The coupling arrangement 30 consists of a snap ring 31, a snap ring recess 32 in the casing 5, a coupling ring 33, and several clamping screws 34. As shown in the drawing, the clamping screws 34 are passed through through holes in the cylinder base housing 3 to the coupling ring 33 and are screwed into the internal threads of the same size, drilled in the coupling ring 33 with the same pitch and pitch diameter.The reverse is also possible, where the through holes for the clamping screws 34 are located in the coupling ring 33 and the corresponding internal threads are located in the cylinder base housing 3. Not shown is the base-side mechanical connection of the complete cylinder 1 when installed in a working machine. This is possible in a variety of ways according to the state of the art using appropriate add-on parts, e.g., a spherical bearing block on the cylinder base housing 3, and therefore does not need to be described further. The same applies to the mechanical connection of the piston rod 7 to the outside.

[0016] Alternatives to the design of the coupling arrangement 30 are shown in detail X and are first described using the Fig. explains: The snap ring 31 is replaced by a spring-loaded square ring 40, based on the snap ring principle, whereby the recess 41 in the casing tube 5.1 and the coupling ring 33.1 are adapted to the rectangular cross-sectional shape of the square ring 40. Instead of the spring-loaded square ring 40, a rigid, but then split, square ring is also possible; the graphic representation remains unchanged.

[0017] A further embodiment of the coupling arrangement 30 is shown in detail X based on the Fig. The jacket tube 5.2 is designed with a stop shoulder 50. The coupling ring 33.2 engages with its inner shoulder 51 in the jacket tube shoulder 50 in a force-locking and form-locking manner, thus ensuring the same principle as the previously described embodiments, namely axial clamping independent of the angular position of the jacket tube 5 and cylinder end piece 3. Instead of a one-piece coupling ring 33.2, a two-piece coupling ring is possible, and in a further embodiment, a full flange or two flange halves according to the well-known SAE standard (ISO 6162) - since the force transmission and form-locking principle is the same in all these cases, the graphic representation remains according to Fig. are basically the same for these alternatives. An arrangement of the clutch 30 on the cylinder head 2 is also possible in an analogous manner, with the two connections A and B being combined on this cylinder side. However, since the relative movements between the driven machine and cylinder head 2 are in most cases greater than with respect to the cylinder base, the Fig. The arrangement shown is mostly cheaper.

[0018] The function of the jacketed tube cylinder 1 according to the invention is outwardly similar to that of a more conventional cylinder. When pressure medium is supplied to A and discharged at B, the piston rod 7 extends; when the supply and discharge of pressure medium are reversed, the piston rod 7 retracts. The annular gap 22 formed by the arrangement of the jacketed tube 5 and cylinder tube 4 serves to convey the pressure medium flowing in or out of the pressure port B, which is routed rearward toward pressure port A, to or from the piston annular chamber 24. The openings 23 enable the exchange of pressure medium between the intermediate chamber 22 and the piston annular chamber 24.

[0019] The positive and non-positive connection by means of the coupling 30, in all variants, allows any desired angular position of the pressure ports A and B to be adjusted to one another during assembly, or as required by the subsequent installation space, without changing the stroke. The force flow within the coupling connection is created by tightening the screws 34 and is transferred via the coupling rings or pieces 33, 33.1, 33.2, the snap ring 31 or square ring 40 in the corresponding recesses 32, 41 in the casing tube or the casing tube shoulder 50 to the casing tube 5, 5.1, 5.2, whereby the casing tube is pressed at the end against the counter surface of the cylinder base housing 3, thus closing the force flow. As a result, the cylinder tube 4 is also fixed in its axial position.

[0020] From the above description of the invention, it is clear that this makes it possible to use cylinders that are easier to install in working or production machines and to utilize the corresponding advantages. Both pressure ports are now located as close together as possible, on one side of the working cylinder, preferably on the bottom side, and their angular position relative to each other can be continuously adjusted, even during or after installation, without any resulting change in the total cylinder stroke.

Claims

[1] Cylinder assembly, actuated by pressure medium, consisting of a piston rod, sealed and guided in a first cylinder end piece as cylinder head - a piston firmly connected to the piston rod, tightly sliding in a cylinder tube, a second cylinder end piece as cylinder base and a first pressure connection (A) in the cylinder base (3) for supplying the piston chamber with pressure medium and a jacket tube (5) surrounding the cylinder tube (4) at a distance (22), characterized by that the pressure medium supply to the piston rod chamber (24) is effected via a second pressure connection (B) in the casing tube, the angular position of which to the first pressure connection (A) is adjustable. [2] Cylinder assembly according to claim 1, characterized by that by means of a positive and non-positive coupling (30) between the jacket tube (5) and the cylinder end piece (3, 2) on the outer diameter of the jacket tube (5), the jacket tube (5) is axially clamped towards the frontal contact surface on the cylinder end piece (3, 2). [3] Cylinder assembly according to claim 2, characterized by that when the coupling (30) is not tensioned, the casing tube (5) can rotate freely relative to the cylinder end piece (3, 2). [4] Cylinder assembly according to claim 2 or 3, characterized by that when the jacket tube (5) is rotated relative to the cylinder end piece (3, 2), the total cylinder stroke is not changed, [5] Cylinder assembly according to one of the preceding claims, characterized by that a pressure connection piece (20) is located on the outer diameter of the casing pipe (5), close to the coupling (30) and thus close to the first pressure connection (A) - usually in the cylinder end piece (3). [6] Cylinder assembly according to claims 1-5, characterized by that the pressure medium supply to the working chamber (24, 19) fed via the pressure connection piece (20) and intermediate space (22) takes place via openings (23) at the end of the cylinder tube (4). [7] Cylinder assembly according to one or more of claims 1 to 6, characterized by that the positive force transmission between the casing pipe (5) and the coupling ring (33) is effected by a wire snap ring (31, 40) with an operating principle according to DIN 7993. [8] Cylinder assembly according to one or more of claims 1 to 5, characterized by that the positive force transmission between the casing pipe (5) and the coupling ring (33) is effected by a multi-part square ring (40). [9] Cylinder assembly according to one or more of claims 1 to 5, characterized by that the positive force transmission between the casing tube (5) and the coupling ring (33) is effected by an outer annular shoulder (50) formed on the casing tube (5) and firmly connected to the casing tube (5). [10] Cylinder assembly according to claim 9, characterized by that the positive and non-positive force transmission between the jacket tube shoulder (50) and the cylinder end piece (3, 2) is carried out by means of SAE full flanges or SEA half flanges standardized according to ISO 6162.

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