Damping cylinder structure unit

Abstract

The invention relates to a damping cylinder assembly having a hydraulic cylinder (10) and a damping energy store (20), the hydraulic cylinder having a cylinder tube (30), a guide closure (40), a bottom closure (50) and a piston unit (60), the cylinder tube (30) having a guide-side cylinder tube end (31) and a bottom-side cylinder tube end (32), the guide closure (40) being arranged on the guide-side cylinder tube end (31), the bottom closure (50) being arranged on the bottom-side cylinder tube end (32), and the piston unit (60) being arranged on the guide-side cylinder tube end (31). The bottom closure (50) has a cylinder tube receiving section (51), a damping accumulator receiving section (52) and a fluid channel (53) connecting the cylinder tube receiving section (51) and the damping accumulator receiving section (52), the cylinder tube (30) being arranged with a bottom-side cylinder tube end (32) on the cylinder tube receiving section (51), the piston unit (60) passes through the guide closure (40) in a sliding manner and forms, together with the cylinder tube (30) and the bottom closure (50), a working chamber connected to the fluid channel (53), the damping energy store (20) has a pressure-resistant shell and a fluid chamber accommodated by the pressure-resistant shell, a pressure-deformable air chamber separated from the fluid chamber by a diaphragm, and a damping energy store fluid connection (21) arranged on the base closure (50), the damping energy store fluid connection (21) being connected to the fluid channel (53).

Description

Technical Field

[0001] The invention relates to a damping cylinder unit for use in particular in demanding fields of application with high dynamic loads, for example in agricultural machinery technology. Background Art

[0002] According to the prior art, it is known that, for example, in agricultural machinery technology, damping devices are provided in soil tillage, in which heavy compression springs are used. This solution is disadvantageous due to the low withstanding forces and the poor characteristic curve.

[0003] In the prior art, hydraulic damping cylinders have proven to be more advantageous. This applies in particular when they are provided with a diaphragm accumulator or a bladder accumulator. The high dynamic loads and the pressure peaks that occur are problematic, which require a particularly strong connection. The complex production required for this is disadvantageous, since a large number of machining operations must be provided for the production of the damping cylinder and the high thermal loads associated with MAG welding, for example, can have a negative impact on the quality and service life and require a high energy consumption. In addition, cleaning of the cylinder interior is disadvantageously required after MAG welding. Therefore, it is known in the prior art to alternatively connect the guide closure by means of a threaded connection. Summary of the invention

[0004] The object of the present invention is to specify a damping cylinder unit which can be produced in a resource-saving, high-quality and short-time manner.

[0005] This object is achieved by the features listed in patent claim 1. Preferred developments are revealed in the dependent claims.

[0006] The damping cylinder structural unit according to the present invention has a hydraulic cylinder and a damping accumulator as basic components. The hydraulic cylinder acts as a pressure flow generator in the case of a moving-in movement and as a pressure flow consumer in the case of a moving-out movement. In the case of a moving-in movement caused by the force brought about by the connected equipment components and to be performed in a damped manner, a fluid flow is generated, and the fluid is pressed into the damping cylinder and accommodated there. Conversely, in the case of a moving-out movement, the fluid is drawn out of the damping accumulator due to pressure and accommodated by the hydraulic cylinder. Throttling of the fluid flow is performed in at least one direction of movement of the fluid, and damping is thereby achieved. The hydraulic cylinder and the damping accumulator are also collectively referred to as a hydraulic assembly below.

[0007] The hydraulic cylinder comprises a cylinder tube, a guide closure, a bottom closure and a piston unit.

[0008] In this case, the cylinder tube has a guide-side cylinder tube end and a bottom-side cylinder tube end. The guide closure is arranged at the guide-side cylinder tube end.

[0009] The bottom end of the hydraulic cylinder is designed in a special manner and has both a cylinder tube receiving section, a damping accumulator receiving section and a fluid channel.

[0010] The cylinder tube is arranged with its bottom-side cylinder tube end on the cylinder tube receiving section and forms a bottom-side axial boundary of the cylinder interior, which is located opposite the guide-side axial boundary of the cylinder interior.

[0011] The piston unit slides through the guide closure and forms a working chamber together with the cylinder tube and the bottom closure. The working chamber is connected to the fluid channel so that the fluid is squeezed out of the gradually shrinking working chamber and pressed into the fluid channel during the inward movement and conversely flows into the working chamber via the fluid channel and can generate an outward movement. The piston unit can be designed in particular as a unit consisting of a piston and a piston rod. However, it can also be designed as a plunger piston, so that in this case the hydraulic cylinder is present as a plunger cylinder.

[0012] In this case, a fluid channel arranged in the bottom closure element connects the cylinder tube receiving section and the damping accumulator receiving section.

[0013] The damping accumulator has a pressure-resistant shell and a fluid chamber accommodated by the pressure-resistant shell and a pressure-deformable air chamber separated from the fluid chamber by a diaphragm. The pressure-deformable air chamber separated by a diaphragm is currently understood to be a structural configuration in which, depending on the fluid pressure, compression of the air enclosed in the air chamber occurs, and thus there is a preload of the air, which acts on the fluid. Due to this compression, the volume of the air chamber decreases, so that the fluid chamber can accommodate more fluid to the same extent. Preferably, it is a diaphragm accumulator, wherein, however, other structural configurations, such as metal bellows accumulators, can also be included in the solution according to the invention.

[0014] Furthermore, the damping accumulator has a damping accumulator fluid connection, which is arranged on the bottom closure. There, the damping accumulator is connected to the bottom closure in such a way that a sealed connection is formed and a firm positional relationship between the bottom closure and the damping accumulator is simultaneously established. The connection can preferably be designed as a laser welded connection.

[0015] The bottom closure element in the functional integration not only forms space for the working chamber of the hydraulic cylinder, but also serves as a base body for force transmission and for mounting, for example, on a machine component and also thirdly as a carrier for the damping accumulator.

[0016] The damping fluid connection is fluidically connected to the fluid channel of the bottom closure element so that the fluid displaced from the hydraulic cylinder during an extension movement can be pressed into the damping cylinder via this path and conversely can be directed back again during an extension movement.

[0017] The damping cylinder assembly according to the invention is characterized in particular by the combination of two beam welding processes in the production of the hydraulic unit consisting of hydraulic cylinder and damping accumulator and thus of two different hydraulic assemblies and their inseparable connection.

[0018] It has been found that by combining two beam welding processes (both of which are based on the application of high-energy beams to the connection partner, but which can meet different specific requirements as an electron beam welding process and as a laser beam welding process), it is possible to produce the damping cylinder unit in an especially high-quality and energy-efficient manner. Advantageously, the special conditions due to the different functional and structural characteristics of the two hydraulic assemblies can thus be met.

[0019] For this purpose, the damping cylinder assembly is characterized in that the damping accumulator is welded on its pressure shell according to the invention by means of an electron beam annular weld. Optionally, a plurality of electron beam welds can also be present on the damping accumulator.

[0020] Furthermore, the damping cylinder assembly is characterized in that the guide closure is integrally connected to the cylinder tube by means of a first annular laser girth weld and the bottom closure is integrally connected to the cylinder tube by means of a second annular laser girth weld.

[0021] The connection according to the invention by means of two annular laser girth welds firstly makes it possible that the hydraulic cylinder, including its components that can be heated only to a limited extent, such as piston seals and guides at the piston or at the guide closure, can be manufactured in such a reliable manner that they do not require serviceability, such as by means of a threaded connection of the guide closure. Since the particularly high dynamic loads of the components that are connected and to be damped require, according to the prior art, a large MAG weld between the cylinder tube and the bottom closure, which disadvantageously loads the connection partner with a large amount of heat, a way was surprisingly found here to use laser welding by means of a special arrangement of the laser girth welds.

[0022] Preferably, the first laser girth weld is designed radially and butt-jointedly, while the second laser girth weld is designed conically at an inclination.

[0023] Advantageously, according to the invention, an electron beam welding process at the damping accumulator and a laser welding process at the hydraulic cylinder are combined in the damping cylinder assembly. With the combination of the electron beam welding process and the laser welding process, a solution is found which enables a time-saving and energy-saving production process and at the same time enables high-quality and process-safe production of the damping cylinder assembly.

[0024] This is based on the fact that, on the one hand, laser welding processes are energetically advantageous for smaller weld seams, in particular those less than 5 mm, while, on the other hand, higher energy efficiency can be achieved with electron beam welding processes in the case of welding of larger gaps, as is the case in the production of damping accumulators. In addition, electron beam welding processes can be more easily adjusted, so that the power density can be adapted. On the other hand, the combination of the two beam welding processes provides advantages that cannot be achieved with the individual use of only one of the two beam welding processes.

[0025] Furthermore, there are particular production advantages, since process-related and occupational safety-related protective measures for one of the welding processes (eg sealing or shielding of the process area) can be used simultaneously for carrying out the other welding process, thereby saving on multiple protective measures.

[0026] Advantageously, the cylinder tube can be constructed with a smaller wall thickness by laser welding, since the additional amount otherwise required according to the prior art for compensating the thread reduction can be omitted. By eliminating the minimum length for the threaded section, a shorter overall length of the cylinder tube can also be advantageously achieved.

[0027] The damping cylinder unit according to the invention has a wide variety of application scenarios, in particular in agricultural machinery, vehicles and in machine construction.

[0028] According to an advantageous improvement, the damping cylinder structural unit is characterized in that the cylinder tube receiving section of the bottom closure has a conical receiving contour and the cylinder tube has a corresponding conical annular surface, and the second laser annular weld is configured with a laser weld inclination angle of 20 to 70 degrees. Due to the conical receiving contour and the corresponding conical annular surface, the two surfaces are disposed opposite each other approximately seamlessly, so that the laser achieves full-surface welding with a penetration depth coordinated therewith and at the same time with low line energy.

[0029] Furthermore, according to this advantageous development, the cylinder tube has an end section which projects axially distally beyond the conical annular surface and has an axial annular surface which bears against an axial counter annular surface of the cylinder tube receiving section.

[0030] In a further advantageous development, the distally projecting end section has a wall thickness that is reduced relative to the wall thickness of the cylinder tube. Preferably, the wall thickness of the distally projecting end section is between 10 and 30 percent of the full wall thickness of the cylinder tube. Furthermore, the distally projecting end section forms an outer surface radially outwardly, which bears against the opposite inner surface of the cylinder tube receiving section.

[0031] These improvements have the advantages described below in particular. The conical receiving contour at the bottom closure and the corresponding conical annular surface at the cylinder tube can be advantageously manufactured in a simple manner and with less material removal by turning and milling. Advantageously from the manufacturing process point of view, it is thus possible to make the self-centering connection of the cylinder tube and the bottom closure to the pre-assembly before laser welding. Preferably, the length of the end section extending far out is also selected so that when the conical receiving contour and the conical annular surface are welded in the assembly position ready to abut against each other, they are brought into axial preload by means of elastic compression in the connection. Laser welding is then performed. The elastic preload is also maintained after the laser welding is completed. Advantageously, the axial annular surface is therefore placed on the axial mating annular surface in a metal-sealed manner during welding, so that the cylinder cavity is reliably protected from contamination during welding. By welding at conical mating surfaces with a laser weld inclination, it is advantageously possible not only to create a larger weld area and provide an unobstructed spatial path for the laser for the weld, but also, in cooperation with the distally protruding end section, to ensure that the weld root does not contact the cylinder interior.

[0032] Particularly advantageously, the geometry of the conical receiving contour of the bottom closure and its extension at the inner surface make it possible to make a particularly stable connection despite high dynamic loads in the interaction with the conical annular surface and its extension through the outer surface and the distal end section. The pressure fluctuations with sudden pressure peaks that occur in the case of the impact to be damped put the connection under load. Due to the preload at the axial annular surface, there is also a barrier at this location, which separates the fluid from the second laser ring weld. In addition, the fluid acts radially on the inner surface of the distal end section. It is particularly advantageous here that, on the one hand, the reduced wall thickness of the distal end section makes it possible to elastically compress and preload it, and on the other hand, it is pressed outward against the inner surface of the cylinder tube receiving section in the case of the radial force of the pressure peak, and therefore in this operating state, there is an increased side friction between the outer surface and the inner surface of the distal end section and the distal end section is radially supported. These factors together effectively reduce the load on the laser weld.

[0033] According to another advantageous improvement scheme, the damping cylinder structural unit is characterized in that the guide closure has a stepped hollow cylindrical receiving contour, the radial outer annular surface of the hollow cylindrical receiving contour is in contact with the inner surface of the cylinder tube, and the guide closure has a proximal (proximale) axial annular surface, which together with the distal axial mating annular surface of the cylinder tube forms a first laser ring weld.

[0034] This further advantageous development relates to the formation of the connection between the guide closure and the cylinder tube and thus to the first laser girth weld.

[0035] Advantageously, the radially outer annular surface of the hollow cylindrical receiving contour and the inner surface of the cylinder tube form a separation which prevents the first laser weld including its weld root from being directly connected to the cylinder tube interior, thereby also preventing contamination of the interior during welding. In addition, the radial form fit supports the connection of the guide closure to the cylinder tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further described by way of example as follows:

[0037] Figure 1 A longitudinal section of the damping cylinder unit is shown;

[0038] Figure 2 An enlarged cross section of the cylinder section on the bottom side is shown;

[0039] Figure 3 An enlarged cross-section of the region showing the second laser girth weld;

[0040] Figure 4 An enlarged section of the guide-side cylinder section is shown. DETAILED DESCRIPTION

[0041] In this case, the same reference numerals in different figures denote respectively the same features or components. Reference numerals are used in the same way in the description even if they are not shown in the relevant figure.

[0042] Figure 1 In one exemplary embodiment, the hydraulic cylinder 10 and the damping accumulator 20 are shown as basic components in a positional relationship defined by a bottom closure 50 .

[0043] In this embodiment, the bottom closure 50 is manufactured as a so-called burnt part, while the cylinder tube receiving section 51, the damping accumulator receiving section 52 and the fluid channel 53 are introduced by cutting to remove material. For the fluid channel, filling and venting openings (without reference numerals) are provided at the top.

[0044] The hydraulic cylinder 10 is formed by a cylinder tube 30 with a guide closure 40 arranged at its guide-side cylinder tube end 31 and a bottom closure 50 arranged at its bottom-side cylinder tube end 32 , as well as a piston unit 60 , which is present here as a plunger piston.

[0045] In this embodiment, the damping accumulator 20 is present as a diaphragm accumulator and (not shown) has a diaphragm in its pressure shell 21, which separates an air chamber from a fluid in a fluid chamber, wherein the air chamber can be compressed by means of the fluid pressure and the volume of the fluid chamber is increased according to the pressure and the resulting degree of compression.

[0046] According to the combination according to the invention consisting of two different beam welds, both laser beam welding and electron beam welding are present. The guide closure 40 is connected to the cylinder tube 30 in a materially bonded manner by means of a first laser girth weld 71. In addition, the bottom closure 50 is also connected to the cylinder tube 30 in a materially bonded manner by means of a second laser girth weld 72. At the same time, the pressure shell 21 of the damping accumulator 20 is welded by means of an electron beam girth weld 22.

[0047] Figure 2 and Figure 3 The bottom closure side region of the hydraulic cylinder 10 in a preferred embodiment is shown in enlarged sectional form. The cylinder tube 30 has a conical annular surface 34, to which the distally protruding end section 33 adjoins. The conical receiving contour 54 is disposed opposite the conical annular surface 34 at the same cone angle. A second laser annular weld 72 is arranged on the joint surface between the conical annular surface 34 and the conical receiving contour 54, which has a laser weld angle α of approximately 30 degrees according to the taper in this embodiment.

[0048] The distally projecting end section 33 tapers significantly relative to the full cylinder tube wall thickness (as it exists in the remaining regions) and also has a slight overhang. This makes it possible to apply a preload to the end section 33 by means of elastic compression even before the second laser annular weld 72 is produced. The axial annular surface 35 and the axial mating annular surface 55 are in contact with each other. In addition, the radial outer surface 36 and the radial inner surface 56 are opposite each other, so that in the case of high pressures, the end section 33, which is designed to taper for elastic preload, comes into pressure contact with the radial inner surface 56 and is supported by it.

[0049] Figure 4 Another enlarged section shows the area of ​​the bottom closure side of the hydraulic cylinder 10 in a preferred embodiment. The guide closure has a stepped hollow cylindrical receiving contour 41 at the connection point with the cylinder tube 30, so that in the radial direction, the radial outer annular surface 42 of the guide closure 40 and the inner surface 37 of the guide side of the cylinder tube 30 are opposite each other, and in the axial direction, the proximal axial annular surface 43 of the guide closure and the axial counterpart annular surface 38 of the guide side are opposite each other. The proximal axial annular surface 43 and the axial counterpart annular surface 38 of the guide side form a butt joint. The first laser ring weld 71 is arranged in a radial orientation (indicated by the dashed line) at this point.

[0050] Reference numerals list

[0051] 10 Hydraulic cylinder

[0052] 20 Damping accumulator

[0053] 21 Pressure hull

[0054] 22 Electron beam girth weld

[0055] 30 Cylinder pipe

[0056] 31 Cylinder tube end on guide side

[0057] 32 Cylinder tube end at bottom side

[0058] 33 Extended end section

[0059] 34 Conical Torus

[0060] 35 Axial ring

[0061] 36 Radial outer surface

[0062] 37 Inner surface of guide side

[0063] 38 Axial mating ring surface on the guide side

[0064] 40 Guide closure

[0065] 41 Stepped hollow cylindrical receiving contour

[0066] 42 Radial outer ring surface

[0067] 43 Proximal axial annulus

[0068] 50 Bottom closure

[0069] 51 Cylinder tube receiving section

[0070] 52 Damping accumulator receiving section

[0071] 53 Fluid Channel

[0072] 54 Conical receiving profile

[0073] 55 Axial matching ring

[0074] 56 Radial inner surface

[0075] 60 Piston Unit

[0076] 71 First laser girth weld

[0077] 72 Second laser ring weld

[0078] α Laser weld inclination angle

Claims

1. A damping cylinder structural unit, comprising a hydraulic cylinder (10) and a damping accumulator (20), in, The hydraulic cylinder comprises a cylinder tube (30), a guide closure (40), a bottom closure (50) and a piston unit (60). The cylinder tube (30) has a cylinder tube end (31) on the guide side and a cylinder tube end (32) on the bottom side. The guide closure (40) is arranged at the cylinder tube end (31) on the guide side. The bottom closure (50) comprises a cylinder tube receiving section (51), a damping accumulator receiving section (52), and a fluid channel (53) connecting the cylinder tube receiving section (51) and the damping accumulator receiving section (52). wherein the cylinder tube (30) is arranged with the bottom-side cylinder tube end (32) on the cylinder tube receiving section (51), The piston unit (60) slides through the guide closure (40) and together with the cylinder tube (30) and the bottom closure (50) forms a working chamber connected to the fluid channel (53). The damping accumulator (20) comprises a pressure-resistant shell and a fluid chamber contained in the pressure-resistant shell, a pressure-deformable air chamber separated from the fluid chamber by a diaphragm, and a damping accumulator fluid interface (21) arranged on the bottom closure (50), wherein the damping accumulator fluid interface (21) is connected to the fluid channel (53). It is characterized in that The damping cylinder structural unit is connected by means of a combination of two beam welding processes. The pressure-resistant shell (21) of the damping accumulator (20) has an electron beam annular weld (22), and The guide closure (40) is connected to the cylinder tube (30) by means of a first annular laser ring weld (71) in a materially sealed manner, and the bottom closure (50) is connected to the cylinder tube (30) by means of a second annular laser ring weld (72) in a materially sealed manner.

2. The damping cylinder structural unit according to claim 1, It is characterized in that The cylinder tube receiving section (51) has a conical receiving contour (54), the cylinder tube (30) has a corresponding conical annular surface (34), the second laser annular weld (72) is constructed with a laser weld inclination angle (α) of 20 to 70 degrees, and the cylinder tube (30) has an end section (33) axially extending distally from the conical annular surface (34), the end section having an axial annular surface (35) which abuts against an axial mating annular surface (55) of the cylinder tube receiving section (51).

3. The damping cylinder structural unit according to claim 2, It is characterized in that The distally projecting end section (33) has a wall thickness of 10 to 30 percent of the wall thickness of the cylinder tube (30) and a radially outer surface (36) which abuts against a radially inner surface (56) of the cylinder tube receiving section (51).

4. The damping cylinder structural unit according to any one of the preceding claims, It is characterized in that The guide closure member (40) has a stepped hollow cylindrical receiving contour (41), the radial outer annular surface (42) of the hollow cylindrical receiving contour (41) abuts against the inner surface (37) of the guide side of the cylinder tube (30), and the guide closure member (40) has a proximal axial annular surface (43) which, together with the distal axial mating annular surface (38) of the guide side of the cylinder tube (30), forms a first laser ring weld (71).

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