PISTON CYLINDER UNIT FOR A WORK MACHINE

Description

[0001] The invention relates to a piston-cylinder unit for a working machine with at least one cylinder and a piston rod displaceably mounted therein, wherein at least one piston rod bearing is provided in the region of the cylinder opening for supporting or guiding the piston rod.

[0002] Piston-cylinder units for hydraulic or pneumatic cylinders are well known. A bearing or guide is provided in the area where the piston rod exits the cylinder housing, for example, in the form of a bearing bush inserted into the cylinder housing. Figures 1-3 Different designs of generic cylinders with piston rod bearings are shown. Figure 1shows a cross-section through the cylinder housing 1 in the area of ​​the cylinder opening, into which a bearing bush 3 is inserted. The bearing bush is provided with an external thread 3a in order to screw the bearing bush 3 into the opening area of ​​the cylinder 1, which has an internal thread. As an alternative, bearing bushes 5 (see Figure 2 ), which are simply inserted into the cylinder opening and fixed using separate 5-edge retaining screws 6.

[0003] CN104315149A shows a piston-cylinder unit according to the preamble of claim 1.

[0004] Depending on the application, there is a desire for a sensor integrated into the cylinder, whether for pressure or length or position measurement. Direct integration of the sensor unit into the bearing bush is desired; the necessary power and signal lines of the sensor unit must then be routed through channels in the bearing bush or the cylinder housing. This is particularly problematic in the embodiment according to Figure 1 , because the bushing 3, which has an external thread 3a, does not offer sufficient space for the sensor unit or the corresponding cable ducts. For this reason, the bearing bushing is designed as shown in Figure 3 shown, extended in the axial direction. However, due to the protrusion of the bearing bush 7 from the cylinder opening, the piston stroke is disadvantageously shortened.

[0005] The idea of ​​the present invention is to show an alternative solution for a piston-cylinder unit or piston rod bearing, which allows a simple and better integration of any component, in particular a corresponding sensor unit.

[0006] This object is achieved by a piston-cylinder unit according to the features of claim 1. Advantageous embodiments of the piston-cylinder unit are the subject of the dependent claims.

[0007] According to the invention, the piston rod bearing used is designed to be at least two-part, with the piston rod bearing consisting of at least one plug-in part that can be inserted or is inserted into the cylinder opening, and at least one screw-threaded part that can be screwed or is screwed to the cylinder wall and serves to fix the plug-in part within the cylinder. According to the invention, the plug-in part comprises an integral sensor unit.

[0008] The plug-in part is simply pushed or inserted into the cylinder opening. The screw part is designed with a matching thread and engages with a complementary thread in the cylinder housing. For example, the screw part has an external thread that interacts with an internal thread of the cylinder in the area of ​​the cylinder opening. Screwing in moves the screw part axially against the plug-in part, thus ensuring sufficient fixation of the plug-in part within the cylinder opening.

[0009] The two-part construction of the bearing bush ensures that a sensor unit is housed in the plug-in part.

[0010] According to a preferred embodiment, the piston rod bearing is designed as a two-part bearing bush. Preferably, the outer circumference of the bearing bush is formed by the assembled bearing parts, while the inner circumference, which accommodates the piston rod, is formed by only one of the bearing parts.

[0011] A preferred embodiment of the screw part is a threaded ring with an external thread. Furthermore, the plug-in part particularly preferably provides a cylindrical projection onto which the threaded ring is placed. When screwed in, the threaded ring exerts a force acting in the axial direction on the plug-in part, thereby pressing it into the cylinder opening. In particular, the plug-in part comprises a corresponding stop surface for the screw part or the threaded ring. A design of the plug-in part with a cylindrical projection for receiving the threaded ring and a stepped diameter increase to the outer diameter of the bearing as a stop surface is conceivable.

[0012] For the exit of corresponding connecting cables of the integral sensor unit, it is possible to provide at least one radial bore in the plug-in part.

[0013] By integrating the sensor unit into the plug-in part, corresponding threaded designs do not interfere with the placement of the radial bore, as these are instead provided on the screw part of the bearing bush. It is also conceivable that the entire sensor unit, including connecting cables, can be screwed into the radial bore. Connecting cables include both signal cables and power supply cables.

[0014] Alternatively, the plug-in part can be provided with an axial bore for the exit of one or more connecting cables of the sensor unit. These can then exit at the front end in the area of ​​the cylinder opening.

[0015] The piston-cylinder unit in question is preferably a hydraulic cylinder or pneumatic cylinder.

[0016] In addition to the cylinder unit, the present invention also relates to a work machine with a piston-cylinder unit according to the invention. Consequently, the same advantages and properties arise for the work machine as already explained above with reference to the piston-cylinder unit according to the invention. For this reason, a repetitive description is omitted.

[0017] The work machine can be a crane or an earthmoving machine or other construction machine.

[0018] Further advantages and features of the invention will be explained in more detail below with reference to the exemplary embodiments illustrated in the drawings. They show: Figures 1-3: different variants of a piston-cylinder unit according to the prior art, Figure 4: a sectional view of a piston-cylinder unit according to the invention in the area of ​​the bearing bush, Figure 5: a sectional view of a further embodiment of the piston-cylinder unit according to the invention in the area of ​​the bearing bush and Figure 6: perspective views of the two-part bearing bush according to the embodiment of Figure 5 .

[0019] Figure 4shows a first embodiment of the piston-cylinder unit according to the invention. This comprises the cylinder housing 10 and a piston rod 20 extending from the cylinder housing 10 and mounted for axial displacement. In the area of ​​the cylinder opening, the two-part bearing bush 30 according to the invention is inserted into the cylinder housing 10. The bearing bush 30 consists of a first bearing part 31 in the form of the threaded ring 31 and the second bearing part in the form of the plug-in bush 32.

[0020] The plug-in bushing 32 is inserted into the cylinder opening during cylinder assembly, in particular until the stop edge 32a abuts a stop surface of the cylinder housing 10 and prevents further penetration of the bearing bushing 30 into the cylinder 10. An integral component of the plug-in bushing 32 is the sensor unit 40, which is inserted into a cavity provided for this purpose in the bearing part 32. Any connecting lines of the sensor unit 40 can be led out of the cylinder housing 10 at the end face of the bearing part 32 via at least one axial bore 41. Furthermore, the plug-in bushing 32 provides a cylindrical projection 32c, onto which the threaded ring 31 can be coaxially mounted.

[0021] The threaded ring 31 itself comprises at least one external thread 31a, which engages with a complementary internal thread of the cylinder housing 10.

[0022] By screwing in the threaded ring 31, it is moved axially into the cylinder housing 10 until the threaded ring 31 abuts the stop surface 32b of the plug socket 32, driving it axially and pressing it with its stop edge 32a against the housing projection. This ensures sufficient fixation of the plug socket 32 ​​within the cylinder 10. The two-part design of the bearing bush 30 also makes it very easy to create space for the sensor unit 40.

[0023] An alternative embodiment of the bearing bush 30 is shown in the illustration according to Figure 5shown. The difference between this bearing bush 30' is that the plug-in bush 32' also includes an integrated sensor unit 40'. However, this unit is screwed with its connecting lines 41' into a radial bore 50 of the plug-in bush 32', so that all sensor lines 41' are also led out of the cylinder housing 10 in the radial direction.

[0024] The Figures 6 and 7 show again perspective views of the bearing bush 30 according to the invention according to the embodiment of Figure 4 The above images show the disassembled bearing bush with the plug-in part 32 and the threaded ring 31. Figure 7 shows the assembled bearing bush 30.

Claims

1. Piston-cylinder unit having a cylinder (10) and a piston rod movably mounted therein, wherein at least one piston bearing (30, 30') is provided in the region of the cylinder opening in order to support or guide the piston rod (20), wherein the piston rod bearing (30, 30') is formed in at least two parts, wherein the piston rod bearing (30, 30') consists of at least one plug-in part (32, 32'), which can be or is inserted into the cylinder opening, and comprises at least one screw part (31, 31') having a thread (31a, 31a'), which can be or is screwed to the cylinder wall and fixes the plug-in part (32, 32') inside the cylinder (10), characterised in that the plug-in part (32) comprises an integral sensor unit (40, 40').

2. Piston-cylinder unit according to claim 1, characterised in that the piston rod bearing (30, 30') is at least a two-part bushing.

3. Piston-cylinder unit according to claim 1 or 2, characterised in that the screw part (31, 31') is a threaded ring, which sits on a cylindrical protrusion (32c) of the plug-in part (32, 32'), and is moved in the axial direction against a stop surface (32b) of the plug-in part (32, 32') when it is screwed to the cylinder wall.

4. Piston-cylinder unit according to any one of the preceding claims, characterised in that the plug-in part (32') comprises a radial bore (50) for discharging one or more connecting lines of the sensor unit (40') and for receiving the entire sensor unit (40'), wherein the radial bore (50) provides a thread that engages with a thread of the sensor unit (40').

5. Piston-cylinder unit according to any one of claims 1 to 3, characterised in that the plug-in part (32) comprises an axial bore (41) for discharging one or more connection lines of the sensor unit (40) in the region of the cylinder opening.

6. Piston-cylinder unit according to any one of the preceding claims, characterised in that the piston-cylinder unit consists of a hydraulic or pneumatic cylinder.

7. Work machine having a piston-cylinder unit according to any one of the preceding claims.