WORKING CYLINDER

Abstract

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged at a first cylinder tube end and the second closure part is arranged at a second cylinder tube end, the cylinder tube and the first and second closure parts define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slidably passes through the first closure part. The first closure part us joined to the cylinder tube in a positive-locking manner by a first circumferential laser ring weld seam. The second closure part is joined to the cylinder tube in a positive-locking manner by a second circumferential laser ring weld seam, and each of the laser ring weld seams define a fluid-tight sealing plane. At least one of the closure parts has an axially opening that is a circumferential concave receiving contour in which the cylinder tube engages. The receiving contour radially overlaps the cylinder tube, and a ring weld seam inclination angle thereof is 110 to 160 degrees.

Claims

1-6. (canceled)

7. A working cylinder, comprising: a cylinder tube, a first closure part, a second closure part and a piston unit; said cylinder tube having a first cylinder tube end and a second cylinder tube end; said first closure part being arranged at said first cylinder tube end and said second closure part being arranged at said second cylinder tube end, said cylinder tube and said first and second closure parts define a cylinder interior; said piston unit defining at least one working chamber in said cylinder interior, said piston unit slidably passing through said first closure part; said first closure part being joined to said cylinder tube in a positive-locking manner by a first circumferential laser ring weld seam, said second closure part being joined to said cylinder tube in a positive-locking manner by a second circumferential laser ring weld seam, and each of said laser ring weld seams defining a fluid-tight sealing plane; at least one of said closure parts having an axially opening being circumferential concave receiving contour in which said cylinder tube engages, said receiving contour radially overlapping said cylinder tube, and a ring weld seam inclination angle thereof is 110 to 160 degrees.

8. The working cylinder according to claim 7, wherein said working cylinder is double-acting and is constructed as a differential working cylinder, said first closure part is constructed as a guide closure part and said second closure part is constructed as a bottom closure part, said first cylinder tube end is a guide-side cylinder tube end and said second cylinder tube end is a bottom-side cylinder tube end; said piston unit includes a piston and a piston rod, said piston is arranged in said cylinder interior and separates said cylinder interior into a first working chamber constructed as a first piston rod working chamber and a second working chamber constructed as a piston rod working chamber, and said piston rod slidably passes through said guide closure part.

9. The working cylinder according to claim 7, wherein said working cylinder is double-acting and is constructed as a synchronized cylinder, said first closure part is constructed as a first guide closure part and said second closure part is constructed as a second guide closure part, said piston unit includes a piston and a piston rod, said piston is arranged in said cylinder interior and separates said cylinder interior into a first working chamber constructed as a first piston rod working chamber and a second working chamber constructed as a piston rod working chamber and said piston rod slidably passes through said guide closure part and said second guide closure part.

10. The working cylinder according to claim 7, wherein said working cylinder is single-acting and is constructed as a plunger cylinder, said first closure part is constructed as a guide closure part and said second closure part is constructed as a bottom closure part, said first cylinder tube end is a guide-side cylinder tube end and said second cylinder tube end is a bottom-side cylinder tube end, said piston unit is a plunger piston with a plunger, said plunger is arranged in said cylinder interior and defines a working chamber in said cylinder interior, and said plunger slidably passes through said guide closure part.

11. The working cylinder according to claim 7, wherein a first circumferential sealing ring is arranged at an axial distance from said first laser ring weld seam in said cylinder interior between said first closure part and a cylinder tube inner wall of said cylinder tube at said first cylinder tube end, said sealing ring defines a first pressure-separated annular section between said first circumferential sealing ring and said first laser ring weld seam, and/or a second circumferential sealing ring is arranged at an axial distance from said second laser ring weld seam in said cylinder interior between said second closure part and said cylinder tube inner wall at said second cylinder tube end, and said second circumferential sealing ring defines a second pressure-separated annular section arranged between said second circumferential sealing ring and said second laser ring weld seam.

12. The working cylinder according to claim 7, wherein each of said laser ring weld seams has a ring weld seam depth, said ring weld seam depth has a ratio of 1.1 to 2.5 relative to a cylinder tube wall thickness.

Description

[0076] The invention is described as an exemplary embodiment in more detail by means of the following figures. They show:

[0077] FIG. 1 Synchronized working cylinder (overview)

[0078] FIG. 2 Enlarged detail to FIG. 1 to show the concave receiving contour

[0079] FIG. 3 Enlarged detail to FIG. 1 in exploded view

[0080] FIG. 4 Enlarged view of a laser weld seam to show the cross-section and the ring weld seam angle beta.

[0081] FIG. 1 shows an embodiment in which the working cylinder is designed as a synchronized working cylinder. In the synchronized working cylinder, both closure parts 3, 4, i.e., the first closure part 3 and the second closure part 4, are designed as guide closure parts. The piston 5a is arranged in the axially central area of the piston rod 5b, which is guided by both closure parts 3, 4. The piston 5a and piston rod 5b together form the piston 5.

[0082] The first cylinder tube end 6 is connected to the first closure part 3 by means of the negatively inclined first laser weld seam 9, and the second cylinder tube end is connected to the second closure part 4 by means of the negatively inclined second laser weld seam 10.

[0083] The two closure parts 3, 4 each have a concave receiving contour 19 into which the obliquely formed annular surfaces of the respective cylinder tube ends 6, 7 are inserted and welded there by means of the laser welding process.

[0084] FIG. 2 shows the embodiment of FIG. 1 in more detail.

[0085] Here, the second cylinder tube end 7 is already inserted into the wedge-shaped concave receiving contour 19 and welded to the second closure part 4 by means of the second circumferential laser ring weld seam 10.

[0086] The ring weld seam centre axis 13 and the main longitudinal axis 14 include the ring weld inclination angle alpha.

[0087] According to the invention, the ring weld seam angle alpha has an angle between 110 and 160 degrees, in the embodiment of about 120 degrees.

[0088] FIG. 3 shows the coupling partners according to FIG. 1 in a schematic exploded view. FIG. 3 shows the first cylinder tube end 6 and the first closure part 3 with the wedge-shaped concave receiving contour 19 before joining. The concave receiving contour 19 is designed to receive the first cylinder tube end 6 and to form a common contact surface with it, on which the first laser ring weld seam 9 is then arranged. FIG. 3 shows that the concave receiving contour 19 opens axially in the direction of the cylinder tube 2. Buckling forces acting radially from the inside on the cylinder tube 2 are thus absorbed in a positive-locking manner by a radial overlap 20. This is the radially outside section of the concave receiving contour 19.

[0089] FIG. 4 shows an enlarged laser weld seam. The first laser ring weld seam 9 shown here, between the first cylinder tube end 2 and the first closure part 3, shows an exemplary laser weld seam according to the present invention.

[0090] This first laser ring weld seam 9 has a ring weld seam depth 11 and a ring weld seam centre axis 13. In this embodiment, the ring weld seam depth 11 is greater than the cylinder tube wall thickness 12.

[0091] The laser weld seam has a slight conicity. If two tangents are put at the edge contour of the laser weld seam, they intersect and form a ring weld seam angle beta. The ring weld seam angle beta is preferably not greater than 15 degrees and in a particularly preferred design not greater than 10 degrees. The ring weld seam centre axis 13 is simultaneously the bisector of the ring weld seam angle beta and includes the ring weld seam inclination angle alpha with the main longitudinal axis 14. Furthermore, the ring weld seam centre axis 13 runs along the contact surface of the first cylinder tube end 6 and the first closure part 3. In this embodiment, the ring weld seam inclination angle alpha is 120 degrees.

[0092] FIG. 4 shows an embodiment with a circumferential sealing ring 17 (O-ring) located in front of the first laser ring weld seam 9, which separates the area in front of the first laser ring weld seam 9 from the pressure medium in a pressure-tight manner. This area is the pressure-separated annular section 18. Viewed axially, the pressure-separated annular section 18 is located between the sealing ring 17 (O-ring) and the first laser ring weld seam 9. In this annular section 18, radial forces do not act from inside on the cylinder tube at its first cylinder tube end 6. Thus, the first laser ring weld seam 9 is only subject to an axial tensile stress. Consequently, the cylinder tube 2 is not loaded with buckling forces in this area and the first laser ring weld seam 9 is relieved. In this embodiment, the sealing ring 17 (O-ring) is made of an elastic polymer. The heat input during laser welding remains sufficiently low to avoid damaging of the sealing ring 21 (O-ring) despite its close proximity to the first laser ring weld seam 9. It is also clear from FIG. 4 in conjunction with FIG. 3 that due to the narrow design of the laser ring weld seams 9, 10 according to the invention, the material in the area of the radial overlap 20 is only thermally stressed up to a small depth so that the corresponding closure part has to have only a small material thickness at the radial overlap 20.

LIST OF REFERENCE NUMERALS

[0093] 1 working cylinder [0094] 2 cylinder tube [0095] 3 first closure part [0096] 4 second closure part [0097] 5 piston unit [0098] 5a piston [0099] 5b piston rod [0100] 6 first cylinder tube end [0101] 7 second cylinder tube end [0102] 8 cylinder interior [0103] 8a first working chamber [0104] 8b second working chamber [0105] 9 first circumferential laser weld seam [0106] 10 second circumferential laser weld seam [0107] 11 ring weld seam depth [0108] 12 cylinder tube wall thickness [0109] 13 ring weld seam centre axis [0110] 14 main longitudinal axis [0111] 15 seal [0112] 20 guide [0113] 21 circumferential sealing ring [0114] 22 pressure-separated annular section [0115] 23 concave receiving contour [0116] 24 radial overlap [0117] α ring weld seam inclination angle alpha [0118] β ring weld seam angle beta