Damping Cylinder Assembly

Abstract

The present invention relates to a damping cylinder assembly including a hydraulic cylinder 10 and a damping accumulator 20, wherein the hydraulic cylinder includes a cylinder pipe 30, a guide closure part 40, a base closure part 50, and a piston unit 60, wherein the cylinder pipe 30 has a guide-side cylinder pipe end 31 and a base-side cylinder pipe end 32, the guide closure part 40 is located at the guide-side cylinder pipe end 31, and the base closure part 50 has a cylinder pipe receiving part 51, a damping accumulator receiving part 52, and a flow passage 53 connecting the cylinder pipe receiving part 51 and the damping accumulator receiving part 52. The cylinder pipe 30 is positioned so that the base side cylinder pipe end 32 is in the cylinder pipe receiving portion 51, the piston unit 60 slides through the guide closure portion 40, and together with the cylinder pipe 30 and the base closure portion 50, forms a working space connected to a flow path 53, and the damping accumulator 20 has a pressure capsule, a fluid chamber accommodated thereby, an air chamber deformable by pressure separated from the fluid chamber by a membrane, and a damping accumulator fluid connection 21 located in the base closure portion 50, and the damping fluid connection 21 is connected to the flow path 53.

Description

[Technical Field]

[0001] The present invention relates to a damping cylinder assembly for demanding applications with high dynamic loads, in particular in agricultural machinery engineering. [Background technology]

[0002] In agricultural machinery engineering, for example in soil cultivation, it is known in the prior art to provide damping systems using powerful pressure springs, a solution that is disadvantageous because it can absorb fewer forces and has a poor characteristic curve.

[0003] The current state of the art shows that hydraulic damping cylinders are more advantageous. This advantage is particularly true when diaphragm or bladder accumulators are installed. The high dynamic loads and resulting pressure peaks require a very strong connection, which presents a problem. Disadvantages include the complex production required for this design, due to the extensive machining required to manufacture the damping cylinder. For example, the high thermal stresses associated with MAG welding can have a negative impact on quality and service life, and require a high energy input. Furthermore, cleaning the cylinder interior after MAG welding is necessary, which is a disadvantage. Therefore, alternative solutions are known in the art, such as connecting guide closures via a threaded connection. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a damping cylinder assembly that can be produced with reduced resource consumption, high quality, and in a short time. [Means for solving the problem]

[0005] The problem is solved by the features set forth in claim 1. Preferred further developments result from the dependent claims.

[0006] The damping cylinder assembly according to the present invention comprises, as its basic components, a hydraulic cylinder and a damping accumulator. The hydraulic cylinder acts as a pressure generator during retraction and as a pressure consumer during extension. During retraction, which is caused by forces introduced by the associated device components and which should be damped, a fluid flow is generated and is forced into the damping cylinder and received therein. Conversely, during extension, fluid is expelled under pressure from the damping accumulator and received by the hydraulic cylinder. In at least one fluid direction of movement, the fluid flow is inhibited, causing damping. Hereinafter, the hydraulic cylinder and the damping accumulator are collectively referred to as a hydraulic unit.

[0007] The hydraulic cylinder comprises a cylinder pipe (hereinafter referred to as a cylinder tube), a guide closure, a base closure, and a piston unit.

[0008] In this design, the cylinder tube has a guide end and a base end, and a guide closure is located at the guide end.

[0009] The base closure of the hydraulic cylinder is designed in a specific way and includes a cylinder tube receiving portion, a damping accumulator receiving portion, and a flow passage.

[0010] The cylinder tube is positioned such that the base cylinder tube end is in the cylinder tube receiving portion and forms a base axial boundary of the cylinder interior opposite the guide axial boundary of the cylinder interior.

[0011] The piston unit slides through the guide closure and, together with the cylinder tube and the base closure, forms a working chamber. This working chamber is connected to a flow channel so that during contraction, fluid is expelled from the contracting working chamber and forced into the flow channel, and conversely, fluid can flow through the flow channel into the working chamber to cause extension. The piston unit can be specifically designed as a unit consisting of a piston and a piston rod, but it can also be designed as a plunger-piston, in which case the hydraulic cylinder is provided as a plunger-cylinder.

[0012] A flow passage provided in the base closure connects the cylinder tube receiving portion and the damping accumulator receiving portion.

[0013] The damping accumulator comprises a pressure capsule, a fluid chamber contained by the pressure capsule, and a pressure-deformable air chamber separated from the fluid chamber by a membrane. In this design, the air chamber separated by the pressure-deformable membrane is understood to be a structural design in which fluid pressure causes compression of the air trapped in the air chamber, creating an air preload acting on the fluid. The compression causes a decrease in the volume of the air chamber, allowing the fluid chamber to correspondingly accept more fluid. Although a diaphragm accumulator is preferably used, other structural designs, such as a metal bellows accumulator, are also encompassed by the solution according to the invention.

[0014] The damping accumulator further comprises a damping accumulator fluid connection arranged on the base closure, where the damping accumulator is coupled to the base closure such that a sealed connection and a fixed positional relationship are created between the base closure and the damping accumulator. Preferably, this coupling can be designed as a laser-welded joint.

[0015] The base closure is functionally integrated in that, firstly, it forms the working chamber of the hydraulic cylinder, secondly, it serves as a base for transmitting forces and for attachment to, for example, a mechanical part, and thirdly, it acts as a carrier for a damping accumulator.

[0016] The damping fluid connection is fluidly connected to the flow path in the base closure, so that fluid expelled from the hydraulic cylinder during retraction movement can be forced into the damping cylinder through this path, and conversely, fluid can be returned during extension movement.

[0017] The damping cylinder assembly according to the invention is characterized in that in the manufacture of a hydraulic unit consisting of two different hydraulic units, the hydraulic cylinder and the damping accumulator, a combination of two beam welding methods is used to provide an irremovable connection.

[0018] It has been found that the combination of two beam welding methods, such as electron beam welding and laser beam welding processes, both of which are based on the application of high-energy radiation to the joining partners but which simultaneously meet different specific requirements, results in a very high-quality and energy-efficient production of damping cylinder units, thereby advantageously making it possible to meet the special requirements based on the different functional and design features of the two hydraulic units.

[0019] For this purpose, the damping cylinder unit is characterized in that the damping accumulator is welded in the pressure capsule by an electron beam annular weld seam. Optionally, several electron beam weld seams can be created in the damping accumulator.

[0020] The damping cylinder assembly is further characterized in that the guide closure is positively materially connected to the cylinder tube by a first peripheral laser annular weld seam, and the base closure is positively materially connected to the cylinder tube by a second peripheral laser annular weld seam.

[0021] The connection according to the invention with two peripheral laser orbital weld seams makes it possible for the first time to manufacture hydraulic cylinders with a high level of quality assurance, including components with only limited heat load capacity, such as piston seals and guides in the piston or guide closure, without the need to provide access for maintenance, for example by threading the guide closure. Whereas according to the current state of the art, the damping of the extremely high dynamic loads imposed by the connected components requires a very large MAG welded joint between the cylinder tube and the base closure, which would impose a high heat load on the connected components, the present invention has surprisingly found a way to apply laser welding by a special arrangement of the laser orbital weld seam.

[0022] Preferably, the first laser orbital weld seam is a radial butt seam and the second laser orbital weld seam is a conical seam with an inclined angle.

[0023] According to the present invention, the electron beam welding method for the damping accumulator and the laser welding method for the hydraulic cylinder are advantageously combined in the damping cylinder assembly. The combination of electron beam welding and laser welding results in a solution that allows for a time-saving and energy-saving manufacturing process, while at the same time ensuring a high-quality and process-reliable production of the damping cylinder assembly.

[0024] The advantages of this combination are based on the fact that, on the one hand, the laser beam welding method is energetically advantageous, especially for smaller weld seams, such as those smaller than 5 mm, and, on the other hand, the electron beam welding method can achieve a high level of energy efficiency when welding larger seams, such as those used in the manufacture of damping accumulators. Furthermore, the electron beam welding method is easier to control, allowing the power density to be adjusted. Furthermore, the advantages offered by the combination of the two beam welding methods cannot be realized by using only one of them.

[0025] Furthermore, a particular advantage for production technology is that process-related and occupational safety-related provisions for one welding process, such as enclosures or shielding of the process area, can be used simultaneously for the other welding method, making multiple protective measures unnecessary.

[0026] Laser welding offers the advantage that cylinder tubes can be designed with thinner thicknesses, since tolerances otherwise required by prior art to compensate for thread material removal can be eliminated. Eliminating the need for a minimum length for the threaded section also allows for shorter construction lengths of the cylinder tube.

[0027] The damping cylinder assembly according to the present invention can be used in a wide range of applications, in particular in agricultural machinery, vehicles and mechanical engineering.

[0028] According to an advantageous further development, the damping cylinder assembly is characterized in that the cylinder tube receiving portion of the base closure has a conical receiving contour, the cylinder tube has a corresponding conical annular surface, and the second laser annular weld seam is formed with a laser weld seam inclination angle of 20 to 70 degrees. The conical receiving contour and the corresponding conical annular surface result in two surfaces facing each other with virtually no gap, and a laser with an appropriately adjusted penetration depth produces a full-surface weld with a simultaneous low energy input per unit length.

[0029] According to this advantageous further development, the cylinder tube has an end portion with an axial annular surface that projects axially distally from the conical annular surface and that abuts against a mating axial annular surface of the cylinder tube receiving part.

[0030] In a further advantageous development, the distally projecting end has a reduced thickness compared to the thickness of the cylinder tube, preferably between 10 and 30 percent of the total thickness of the cylinder tube, and furthermore, the distally projecting end defines a radially outer outer surface that abuts the opposing inner surface of the cylinder tube receiving part.

[0031] These further developments have the specific advantages described below. The conical receiving contour of the base closure and the corresponding conical annular surface of the cylinder tube can be advantageously produced by a turning process in a simple manner and with minimal material removal. From a manufacturing standpoint, this process advantageously allows for a self-centering joining of the cylinder tube with the base closure at the same time, allowing for the formation of a pre-assembled assembly prior to laser welding. Furthermore, the length of the distally protruding end is preferably selected so that, when joining is performed, this portion is axially preloaded by elastic compression when the conical receiving contour and the conical annular surface contact each other in the assembled position, and is ready for welding. Laser welding is then performed. The elastic preload is maintained even after the laser welding process is completed. Advantageously, the axial annular surface is already in metal-sealing contact with the axial mating annular surface during welding, reliably protecting the interior of the cylinder from contamination during the welding process. Advantageously, welding on a pair of conical surfaces with a laser weld seam inclination angle creates a larger weld seam area, providing unobstructed spatial access to the weld seam for the laser, and in combination with the distally protruding ends ensures that the root of the weld seam does not come into contact with the interior of the cylinder.

[0032] A particular advantage is that the conical receiving contour of the base closure and the geometry of the continuation at the inner surface, together with the continuation at the outer surface and the distally protruding end, allow for a very stable connection even under high dynamic loads. Pressure fluctuations with sudden pressure peaks occurring during damped impacts stress the connection. Furthermore, the preload on the axial annular surface creates a barrier separating the fluid from the second laser orbital weld seam. Furthermore, the fluid acts radially on the inner surface of the distally protruding end. It is particularly advantageous that, on the one hand, the reduced thickness of the distally protruding end allows for elastic compression and prestressing, and, on the other hand, this area is pushed outward against the inner surface of the cylinder-tube receiving part by pressure peaks during the application of radial forces. Therefore, in this operating state, the lateral friction between the outer and inner surfaces of the distally protruding end is consequently increased, radially supporting the distally protruding end. These factors together effectively reduce the load on the laser weld seam.

[0033] According to a further advantageous development, the damping cylinder assembly is characterized in that the guide closure has a stepped hollow cylindrical receiving contour, the radially outer annular surface of which contacts the inner surface of the cylinder tube, and the guide closure has a proximal axial annular surface which, together with the distal axial mating annular surface of the cylinder tube, butt-jointly forms a first laser annular weld seam.

[0034] This advantageous further development applies to the formation of the connection between the guide closure and the cylinder tube, first by laser orbital welding.

[0035] Advantageously, the outer radial annular surface of the hollow cylindrical receiving contour and the inner surface of the cylinder tube form a separation that includes the root of the weld seam and prevents direct connection of the first laser weld seam to the interior of the cylinder, thereby preventing internal contamination during welding. Furthermore, the radial form fit assists the connection of the guide closure to the cylinder tube.

[0036] The invention is explained in more detail by way of exemplary embodiments with the aid of the following drawings, in which: [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a longitudinal cross-sectional view of a damping cylinder assembly. [Figure 2] FIG. 4 is an enlarged cross-sectional view of a base-side cylinder portion. [Figure 3] FIG. 10 is an enlarged cross-sectional view of the area of ​​the second laser orbital weld seam. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a guide-side cylinder portion. DETAILED DESCRIPTION OF THE INVENTION

[0038] The same reference numbers in each figure always refer to the same feature or component, and reference numbers are used herein even if they are not shown in the figure to which they refer.

[0039] FIG. 1 shows an embodiment in which the basic components, a hydraulic cylinder 10 and a damping accumulator 20, are in a positional relationship defined by a base closure 50.

[0040] In this embodiment, the base closure 50 is produced as a so-called flame-cut part, and the cylinder tube receiving part 51, the damping accumulator receiving part 52 and the flow passage 53 are produced in a subtractive machining process. Filling and discharge openings (not numbered) are provided in the flow passages at the top.

[0041] The hydraulic cylinder 10 is formed by a cylinder tube 30 together with a guide closure 40 arranged at the guide cylinder tube end 31, a base closure 50 arranged at the base cylinder tube end 32, and a piston unit 60, here provided as a plunger piston.

[0042] In this exemplary embodiment, the damping accumulator 20 is designed as a diaphragm accumulator, comprising a diaphragm (not shown) separating an air chamber from the fluid in the pressure capsule 21, the air chamber being compressible by fluid pressure, the volume of the fluid chamber increasing depending on the pressure and the resulting degree of compression.

[0043] The combination of two different types of beam welding seams invented applies both laser beam welding and electron beam welding. The guide closure 40 is connected in a positive material manner to the cylinder tube 30 by a first laser orbital weld seam 71. Furthermore, the base closure 50 is also connected in a positive material manner to the cylinder tube 30 by a second laser orbital weld seam 72. Furthermore, the pressure capsule 21 of the damping accumulator 20 is welded by an electron beam orbital weld seam 22.

[0044] 2 and 3 each show an enlarged cross-sectional view of the base closure side region of the hydraulic cylinder 10 in a preferred embodiment. The cylinder tube 30 has a conical annular surface 34 proximate the distally projecting end 33. A conical receiving contour 54 is located opposite the conical annular surface 34 and has the same cone angle. A second laser annular weld seam 72 is located at the interface between the conical annular surface 34 and the conical receiving contour 54 and, due to its conical shape, has a laser weld seam inclination angle α of approximately 30 degrees in the exemplary embodiment.

[0045] The distally projecting end 33 is significantly tapered relative to the entire cylinder tube thickness as present in the remaining region and has a slight excess length, which allows the end 33 to be preloaded by elastic compression before the second laser annular weld seam 72 is created. The axial annular surface 35 and the axial mating annular surface 55 abut each other. Furthermore, the radially outer surface 36 and the radially inner surface 56 face each other so that the end 33, which is designed to be tapered for elastic preloading, is pressed against and supported by the radially inner surface 56 under high pressure.

[0046] FIG. 4 shows the base closure-side region of the hydraulic cylinder 10 in another enlarged cross-sectional view in a preferred embodiment. The guide closure has a stepped hollow-cylindrical receiving contour 41 at its connection point to the cylinder tube 30, with the radially outer annular surface 42 of the guide closure 40 and the guide-side inner surface 37 of the cylinder tube 30 facing each other radially, and the proximal axial annular surface 43 of the guide closure and the guide-side axial mating annular surface 38 facing each other axially. The proximal axial annular surface 43 and the guide-side axial mating annular surface 38 form a butt joint. A first laser-welded annular seam 71 is radially arranged here, as indicated by the dashed line. [Explanation of symbols]

[0047] 10 Hydraulic Cylinder 20 Damping Accumulator 21 Pressure Capsule 22 Electron beam orbital welding seam 30 Cylinder tube 31 Guide side cylinder tube end 32 Base side cylinder tube end 33 Protruding End 34 Conical toroidal surface 35 Axial annular surface 36 Radial outer surface 37 Guide side inner surface 38 Guide side axial mating annular surface 40 Guide Closure 41 Graduated hollow cylindrical receiving contour 42 Radial outer annular surface 43 Proximal axial annular surface 50 base closure 51 Cylinder tube receiving part 52 Damping accumulator receiving portion 53 Flow path 54 Conical receiving contour 55 Axial mating annular surface 56 Radial inner surface 60 Piston Unit 71 First laser orbital weld seam 72 Second laser orbital weld seam α Laser welding seam inclination angle

Claims

1. A damping cylinder assembly comprising a hydraulic cylinder (10) and a damping accumulator (20), The hydraulic cylinder comprises a cylinder tube (30), a guide closure (40), a base closure (50), and a piston unit (60); The cylinder tube (30) has a guide-side cylinder tube end (31) and a base-side cylinder tube end (32); The guide closure (40) is arranged at the guide cylinder tube end (31), the base closure (50) comprises a cylinder tube receiving portion (51), a damping accumulator receiving portion (52), and a flow passage (53) connecting the cylinder tube receiving portion (51) and the damping accumulator receiving portion (52); the cylinder tube (30) is positioned such that the base cylinder tube end (32) is in the cylinder tube receiving portion (51); the piston unit (60) slides through the guide closure (40) and together with the cylinder tube (30) and the base closure (50) forms an operating chamber connected to the flow path (53); A damping cylinder assembly, wherein the damping accumulator (20) comprises a pressure capsule (21), a fluid chamber contained therein, and an air chamber deformable by pressure separated from the fluid chamber by a diaphragm, and a damping accumulator fluid connection (21) arranged in the base closure (50), the damping accumulator fluid connection (21) being connected to the flow path (53), The damping cylinder unit is joined by a combination of two beam welding methods; the pressure capsule (21) of the damping accumulator (20) is provided with an electron beam orbital weld seam (22); the guide closure (40) is connected in a positive material manner to the cylinder tube (30) by a first peripheral laser annular weld seam (71); The base closure (50) is connected in a positive material manner to the cylinder tube (30) by a second peripheral laser orbital weld seam (72). A damping cylinder assembly comprising:

2. The cylinder tube receiving portion (51) has a conical receiving contour (54), the cylinder tube (30) has a conical annular surface (34) corresponding to the conical receiving contour (54), the second laser annular weld seam (72) is formed with a laser weld seam inclination angle (α) of 20 degrees to 70 degrees, the cylinder tube (30) has an end portion (33) that protrudes axially distally from the conical annular surface (34), and the end portion (33) has an axial annular surface (35) that is in contact with an axial mating annular surface (55) of the cylinder tube receiving portion (51).

2. The damping cylinder assembly of claim 1 .

3. 3. The damping cylinder assembly of claim 2, wherein the distally protruding end portion (33) has a thickness of 10 to 30 percent of the thickness of the cylinder tube (30), and the end portion (33) has a radially outer surface (36) that contacts a radially inner surface (56) of the cylinder tube receiving portion (51).

4. The guide closure (40) comprises a stepped hollow cylindrical receiving contour (41), a radially outer annular surface (42) of which contacts the guide-side inner surface (37) of the cylinder tube (30), and the guide closure (40) comprises a proximal axial annular surface (43), which butt-jointly forms the first laser annular weld seam (71) together with the guide-side distal axial mating annular surface (38) of the cylinder tube (30). A damping cylinder assembly according to any one of claims 1 to 3, characterized in that it comprises:

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