AT512663B1 - Cylinder-piston unit - Google Patents

Abstract

The invention relates to a cylinder-piston unit (1), the piston (4) of which is connected to a piston rod (3) projecting from an end face of the cylinder (2) and which has a variably adjustable stroke limiting device in the form of a stop mechanism (5). a stop part (6) and a counter stop part (11), wherein the stop part (6) is fastened with a first section (7) to a part of the piston rod (3) projecting out of the cylinder (2) and with a second section (Fig. 8) which extends outwardly along the cylinder (2) cooperates in a stop position with the counter-abutment part (11), and wherein the counter-abutment part (11) is held axially with respect to the cylinder (2) and the counter-abutment part (11) relatively the stop member (6) is rotatable, wherein the stop member (6) and counter stop member (11) forming different stop pairs depending on the relative rotational position, through which the path of the piston rod (3) varies in strength is limited. In this case, the counter-abutment part (11) forms different limit stops (12, 13), which are each assigned to the different pairs of stops.

Description

Austrian Patent Office AT512 663B1 2013-10-15

Description: The invention relates to a cylinder-piston unit, the piston of which is connected to a piston rod projecting from an end face of the cylinder and which has a variably adjustable stroke limiting device in the form of a stop mechanism comprising a stop member and a counter stop member, wherein the stop member is attached to a first portion of a protruding from the cylinder part of the piston rod and with a second portion which extends along the outside of the cylinder, cooperates in a stop position with the counter-stop member, and wherein the counter-stop member is held axially with respect to the cylinder, and the counter-stop member is rotatable relative to the stop member, wherein the stop member and the counter-stop member depending on the relative rotational position form different pairs of stops through which the path of the piston rod can be limited to different degrees.

In the prior art, there is a need for precisely acting drive units whose movements are reliably controlled and precisely defined. In particular, in the exact alignment of tools that are used alternately in two different positions, e.g. in a lower tool which is used on a bending machine both for folding and for pressing and is adjustable in the direction of the so-called I-axis, such drive units are used. These consist of a cylinder-piston unit, whose protruding at one end face of the cylinder piston rod drives the tool. In the context of such cylinder-piston units, there is so far no solution to limit the stroke of the piston rod in a reliable, space-saving and cost-effective manner.

US76732A discloses a hydraulic press, in particular for pressing tobacco with a cylinder and a ring arranged above the cylinder and having at its top gradations, which is rotatable with respect to the cylinder and acts as a holding device for the sitting on the piston rod pressing head , The pressing head is connected to the bottom of the pressing frame via vertically extending rods. The holding device allows the holding of the pressing frame in different height positions.

US3177980A discloses a hydraulic locking device for controlling the relative movement of two parts. An extending beyond the cylinder stop sleeve has in its wall axially extending slots, which have gradations at one of its ends. A pin connected to the piston rod and diametrically oriented pin engages in this slot, whereby its way through the stepped end of the slot is limited. The sleeve is rotatable, whereby the desired gradation can be selected as a stroke limitation.

DE1964126A1 discloses a locking device for controlling the relative movement between two parts with a hydraulic cylinder which is connected to one of the two parts. A stop means consists of a first stop, which is drivingly connected to the cylinder, and a second stop, which is drivingly connected to the piston rod. Is on the tubular piston rod. First and second stops cooperate to limit the range of the piston stroke. The stop connected to the piston rod consists of an axially adjacent to the cylinder stop sleeve in which a plurality of gradations are formed in the circumferential direction and which is rotatable about the cylinder axis. With the gradations act radially extending stop fingers of the stop connected to the cylinder.

FR1596551A discloses a stroke limiter for a cylinder with rods along which stops are linearly adjustable. These rods are guided on a radial extension on the cylinder head and connected to the piston rod via a frame.

The non-generic EP0346504A1 discloses a rodless piston-cylinder assembly with a device for stroke limitation. The stroke limiter comprises a drum mounted rotatably next to the cylinder, from which limit stops of different lengths protrude parallel to the cylinder longitudinal axis along its circumference. One along the 1/15 Austrian Patent Office AT512 663B1 2013-10-15

Cylinder movable drive part, which is coupled via magnetic arrangements with the piston contactless, forms a stop member, which cooperates with the respectively brought into position limit stop of the drum. The stroke limitation disclosed in EP0346504A1 is not transferable to cylinders with piston rods. A disadvantage of this arrangement is that the drive member is loaded asymmetrically during the attack. In addition, the movement of the drive member can be limited with the device for limiting the stroke in one direction only.

FR988036A discloses a lathe having a feed shaft with an adjustable stop. A rotatable about the shaft axis rotating part encloses the shaft and defined depending on the rotational position of a certain limit stop, with which cooperates a tailed to the movable part of the feed shaft stop member. This document is far from the subject invention, since it does not relate to a cylinder-piston unit. As with EP0346504A1, a limitation of the movable part is only possible in one direction.

The object of the invention is to provide a cylinder-piston unit with which the movement of the piston rod can be defined reliably and adjustable. Preferably, the path of the piston rod should be limited in both directions and variably adjustable. The solution should be space-saving and cost-effective. In particular, the cylinder-piston unit should have a compact construction and be installed in common machine tools without complex adaptations.

This object is achieved with a cylinder-piston unit of the type mentioned above in that the counter-stop part forms different limit stops, which are each assigned to the different stop pairings.

Such a solution not only allows a reliable and defined adjustable stroke limitation, but also a space-saving, compact design. The latter allows the use of inventive cylinder-piston units in common (tool) machines without complex adaptations. The travel limit for the displacement of tools is thus already integrated into the drive and requires no additional measures, whereby the cost of upgrading a machine with a variable path limitation are kept low.

The second portion may extend outwardly along the cylinder both adjacent thereto and spaced therefrom.

The limit stops associated with the different pairs of stops have different height or extent in the axial direction and therefore limit the axial travel to different degrees. Preferably, the limit stops are integrally formed in the counter-stop piece. At least those limit stops that limit the travel of the stop member in an axial direction are preferably formed integrally with the counter stop member, respectively.

Preferably, the counter-stop member is rotatable relative to the cylinder and forms different limit stops, which are each assigned to the different pairs of stops. The axially fixed and thus clearly defined in its axial position counter stop allows the realization of exactly reproducible limit stops and can also be designed as a compact component.

Preferably, the counter-abutment part forms on both of its end faces, which are axially spaced from each other with respect to the cylinder longitudinal axis, in each case different limit stops, so that the path of the piston rod can be limited to different degrees in both directions. This results not only in a direction of the piston rod differently adjustable stop pairings, but also in the opposite direction. This increases the flexibility and possible applications of a cylinder-piston unit.

Preferably, the counter-abutment part is formed from two mutually rotatable sections, wherein one of the two end faces of the counter-abutment part is formed on the one of the two paragraphs and the other end face of the counter-abutment part on the other Section is formed. As a result, with respect to both directions of movement of the piston rod, any desired combinations of stop pairings can be set and the end stops can be adjusted as required both for the extension and the retraction of the piston rod.

Preferably, the second portion of the stop member is formed by at least one elongate arm which extends substantially parallel to the longitudinal axis of the cylinder. Such a running arm takes up little space, whereby the cylinder-piston unit can be designed to save space.

Preferably, the second portion of the stop member is formed by at least two substantially mutually parallel arms extending along opposite sides of the cylinder. This allows a symmetrical loading of the stop member and the counter-stop member during the stop, whereby wear or jamming of the moving parts is prevented.

Preferably, the second portion of the stop member has two axially spaced relative to the cylinder longitudinal axis, cooperating with the counter stop member stop structures and projects the counter stop part at least partially in the area between the stop structures, so that the path of the piston rod can be limited in both directions. With only one stop member thus the way in both directions of the piston can be limited, whereby the potential applications of the cylinder-piston unit can be increased.

Preferably, the stop structures are in the form of lugs which protrude radially outward with respect to the cylinder. This is a particularly simple way to create limits on the opposite directions without increasing space requirements.

Preferably, the counter-abutment part is arranged at the level of the cylinder. In this case, the counter-stop part enclose the cylinder or be arranged next to the cylinder, whereby a particularly compact design is achieved.

Preferably, the counter-abutment part is rotatable about the longitudinal axis of the cylinder. This represents a particularly space-saving and easy-to-use design.

Preferably, the counter-stop member is formed in the form of a sleeve enclosing the cylinder. Since the thickness of the sleeve wall can be kept low, the space required is further reduced by this design. In addition, this results in a compact design.

Preferably, the different limit stops are formed by a step-shaped wall of the sleeve. The counter-abutment can thus be made compact and easy. The steps in the wall can e.g. be formed in a wall recess which opens in the axial direction. Alternatively, the steps could be axial protrusions.

Preferably, the counter-stop member is made in the form of the sleeve together with the integrated limit stops from one piece.

Preferably, a seated on the cylinder holder is provided for axially holding the counter-abutment part. Here, the cylinder assumes the additional function of holding the counterpart stop part. The holder can be attached directly or indirectly to the cylinder.

Preferably, the holder is formed from at least two axially spaced, radially outwardly projecting projections, between which the counter-stop member is inserted, resulting in a reliable axial fixation.

Preferably, the projections at least partially run around the cylinder. In addition to a simple production of the fixation of the counterpart stop part is ensured. 3/15 Austrian Patent Office AT512 663 B1 2013-10-15

Its rotatable bearing relative to the cylinder is positively influenced by the projections.

Preferably, the second portion of the stop member is guided by the projections in the axial direction. The projections thus assume a further function, resulting in a particularly compact and protected from wear structure.

Preferably, the holder is formed on an intermediate sleeve arranged between the counter-stop member and the cylinder, on which the counter-stop member is rotatably mounted. A conventional cylinder-piston unit can be easily retrofitted in this way, in which the cylinder adapted to the sleeve intermediate sleeve together with counter stop and stop member are placed on the cylinder.

Preferably, the counter-abutment part is rotatable about an axis of rotation, which is arranged laterally spaced from the cylinder and is substantially parallel to the cylinder longitudinal axis. In this embodiment, the counter-stop member is separately and spaced from the cylinder accessible.

Preferably, the counter-stop member is formed as a drum whose longitudinal axis coincides substantially with its axis of rotation. A drum is easy to handle and provided with various limit stops.

Preferably, the limit stops are formed on a front side of the drum as sector-wise gradations. The limit stops are thus integrally formed in the counter-stop part.

Preferably, a lower portion of the cylinder is connected to a lower portion of the rotation axis via a first connecting member and an upper portion of the cylinder is connected to an upper portion of the rotation axis via a second connecting member. This results in a stable construction which prevents relative displacement between the cylinder and the counter-abutment part.

Preferably, a passage is provided in one of the connecting elements, through which the stop member is passed. By this construction, the stop member is better protected from external mechanical influences and the implementation can even serve as an axial guide for the stop member.

Preferably, the second portion of the abutment part extends between the cylinder and the counterpart stop part. The stop member may extend entirely or only partially between the cylinder and stop member. In addition to a compact design, the stop member can thereby be guided and / or better protected against mechanical influences.

Preferably, the counter-stop member is rotated manually, so that a simple adjustment of a certain limit stop can be made in the path of the stop member. The stop combination can be adjusted by hand relatively fast and repeatable.

Preferably, the counter-abutment part cooperates with a latching device, with which the respective stop pairings associated rotational positions of the counter-abutment part can be locked. This prevents an already set limit stop, e.g. shaken out of position.

Preferably, the latching device comprises a preferably spring-loaded ball pressure piece. This constitutes a simple and reliable variant. The latching device allows the counter-stopper to be frictionally engaged in any position (for example in the case of a drum or sleeve in each sector).

Preferably, the cylinder-piston unit comprises means for measuring the distance covered piston travel (displacement measuring system for cylinder position). In addition to the Hubbegrenzungseinrichtung thereby the set piston travel can be checked.

Preferably, the cylinder-piston unit comprises means for measuring the relative rotational position of the counter-abutment part, in particular in the form of an angle measuring device (path measuring system for drum or sleeve angle). This makes it possible to check whether the desired stop pairing has been set correctly. Preferably, the cylinder-piston unit is pneumatically actuated and thus constitutes a pneumatic drive with a plurality of end stops. Especially with pneumatically actuated cylinders, the stroke limiting device according to the invention represents a special supplement to their possible uses ,

A preferred application of a cylinder-piston unit according to the invention is a bending machine for bending particular flat workpieces with a lower tool (or die) and a top tool, which are movable towards each other by a first drive to effect the bending operation. A second drive is intended to move the lower tool as such, e.g. to adjust or adapt to different workpiece sizes. For this shift, a cylinder-piston unit according to the invention could now be used as the second drive. The axis defined by the second drive is usually also referred to as the I-axis. A cylinder-piston unit according to the invention is much cheaper than a CNC-controlled drive and much easier to use than previous pneumatic I-axes.

The cylinder drive can thus be used efficiently and safely for the I-axis movement of a bending machine.

Finally, it should be emphasized that the embodiments can be realized without loose or loose projecting parts with a positive influence on life and handling.

A particular embodiment includes that on a pneumatic cylinder, a mechanism is attached, which is partially bound to the movable system or partially to the fixing system. Fixed and moving parts have different end stops with each other. The mechanism can be adjusted so that the end stops (measured in the stroke direction) change digitally.

In one implementation example, there is a drum (counter-abutment part) which has two matching, predefined end stops in its sectors. The drum is in the fix system. A fork (abutment member) having two abutment surfaces / structures is coupled to the movable system. The drum can be rotated by hand and thus the different pairs of stops are set.

This drum can be split in length 2 to obtain double stop combinations.

In another implementation example is a (compact) cylinder with adjacent stop mechanism.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

[0054] [0056]

Each shows in a highly schematically simplified representation:

Fig. 1 shows a first embodiment of a cylinder-piston unit according to the invention;

FIG. 2 shows the cylinder-piston unit from FIG. 1 with the piston rod extended to different extents; FIG.

3 shows a second embodiment of a cylinder-piston unit according to the invention;

FIG. 4 shows the cylinder-piston unit from FIG. 3 with the piston rod extended to different extents; FIG.

5 shows the cylinder-piston unit of Figure 3 with partially cut stop mechanism ..; FIG. 6 shows the cylinder-piston unit of FIG. 3 with a partially cut-open stop mechanism, wherein the sectional plane is inclined by 90 ° with respect to the sectional plane of FIG. 5; FIG. 5/15 Austrian Patent Office AT 512 663 B1 2013-10-15 [0058] FIG. 7 shows a cylinder-piston unit in section along the cylinder longitudinal axis.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis transferred to like parts with the same reference numerals or identical component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position.

The embodiments show possible embodiments of the cylinder-piston unit, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but also various combinations of the individual embodiments are mutually possible and this variation possibility due the doctrine of technical action by objective invention in the skill of those working in this technical field is the expert. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

1 and 2 show a first embodiment of a cylinder-piston unit 1. A displaceably arranged in the interior of the cylinder 2 piston is connected to the protruding at the end face of the cylinder 2 piston rod 3 (similar to FIG. 7 shown). The cylinder 2 defines a cylinder longitudinal axis 20. FIG. 1 shows an extended position of the piston rod 3 and FIG. 1 a retracted position of the piston rod 3. The cylinder-piston unit 1 has a variably adjustable stroke limiting device in the form of a stop mechanism 5, the one Stopper 6 and a counter-stop part 11 includes.

The stop member 6 is fixed with a first portion 7 on a protruding from the cylinder 2 part of the piston rod 3 and acts with a second portion 8, which extends outside along the cylinder 2, in the respective stop position with the counter-stop member 11 together.

The counter-abutment part 11 is - viewed in the axial direction - arranged at the height of the cylinder 2 and axially fixed with respect to the cylinder 2. The counter-stop member 11 is rotatable relative to the stop member 6, wherein stop member 6 and counter-stop member 11 depending on the relative rotational position form different pairs of stops, through which the path of the piston rod 3 can be limited to different degrees.

The counter-abutment part 11 is rotatable relative to the cylinder 2 and forms different limit stops 12, which are each assigned to the different stop pairings. The counter-abutment part 11 can each form different limit stops on both of its end faces, which are axially spaced apart relative to the cylinder longitudinal axis 20, so that the travel of the piston rod 3 can be limited to different degrees in both directions.

The second portion 8 of the stop member 6 is formed by an elongate arm which extends substantially parallel to the longitudinal axis 20 of the cylinder 2, and has two with respect to the cylinder longitudinal axis 20 axially spaced apart, with the counter-stop member 11 cooperating stop structures 9, 10 on. The counter-abutment part 11 projects with a peripheral part into the area between the stop structures 9, 10, so that the travel of the piston rod 3 can be limited in both directions. The stop structures 9, 10 are in the form of lugs which project radially outward with respect to the cylinder 2.

In the illustrated embodiment, the counter-abutment part 11 is rotatable about a rotation axis 19, which is arranged laterally spaced from the cylinder 2 and is substantially parallel to the cylinder longitudinal axis 20.

The counter-abutment part 11 is in the form of a drum whose longitudinal axis substantially coincides with its axis of rotation 19. The different limiting abutment 12 are formed on one end face of the drum as sector-wise graduations. 1 and 2, only the upper limit stops 12 can be seen, however, correspondingly formed limit stops (for the lower stop structure 9) can also be provided on the lower end face of the drum. The drum may also be formed 2-divided along its length to obtain double stop combinations. In this embodiment, the counter-abutment part 11 is formed of two mutually rotatable portions, wherein one of the two end faces of the mating stop member 11 is formed on the one of the two sections and the other end face of the mating stop member 11 is formed on the other portion. In Figs. 1 and 2, the upper portion is rotatable against the lower portion (indicated by a dividing line).

A lower portion of the cylinder 2 is connected to a lower portion of the rotation shaft 19 via a first connecting member 21, and an upper portion of the cylinder 2 is connected to an upper portion of the rotation shaft 19 via a second connecting member 22. As a switching element, e.g. as shown in FIGS. 1 and 2 serve a rod which extends between the first and second connecting element and whose longitudinal axis preferably coincides with the axis of rotation 19.

In the upper connecting element 22, a passage 23 is provided, through which the stop member 6 is passed. From Fig. 1 and Fig. 2 it can be seen that the elongated second portion 8 of the stop member 6 between the cylinder 2 and counter-stop member 11 extends.

FIGS. 3 to 6 show another embodiment of a cylinder-piston unit 1 which is independent of itself, again using the same reference numerals or component designations for the same parts as in the preceding FIGS. 1 and 2. In order to avoid unnecessary repetition, reference is also made to the detailed description in the preceding FIGS. 1 and 2 or referenced. In this case, the piston rod is retracted in Fig. 3 and extended in Fig. 4, while in Figs. 5 and 6 of the stop mechanism is shown in part 'cut'. As a supplement, FIG. 7 shows a section along the cylinder longitudinal axis 20 and the piston 4 which is movable in the cylinder 2.

In the embodiment of FIGS. 3 to 6, the counter-abutment part 11 is rotatable about the longitudinal axis 20 of the cylinder 2 and also forms different limit stops 12, 13, which are each assigned to the different stop pairings.

The counter-abutment part 11 forms on both of its end faces, which are axially spaced from each other with respect to the cylinder longitudinal axis 20, each of different limit stops 12, 13, so that the path of the piston rod 3 is different degrees limited in both directions.

The first portion 7 of the stop member 6 is in the example shown a disc which is pushed with its central opening on the piston rod 3 and fixed there by means of nuts.

The second portion 8 of the stop member 6 is formed by two substantially mutually parallel arms which extend along opposite sides of the cylinder 2 and extend substantially parallel to the longitudinal axis 20 of the cylinder 2. The stop member 6 has here the shape of a fork.

Also in this embodiment, the second portion 8 of the stop member 6 has two with respect to the cylinder longitudinal axis 20 axially spaced, cooperating with the counter stop member 11 stop structures 9, 10 (eg in the form of radially outwardly projecting lugs), wherein the counter-stop member 11 partially projects into the area between the stop structures 9, 10, so that the path of the piston rod 3 can be limited in both directions.

The counter-abutment part 11 is formed in the form of a cylinder 2 enclosing and rotatable about the cylinder sleeve 14. The different limit stops 12, 13 on the upper and on the lower end face of the sleeve 14 are formed by a step-shaped wall of the sleeve 14. Also in this embodiment, the counter-abutment part 11 could be formed from two mutually rotatable sections, so that the upper limit stops 12 and the lower limit stops 13 additionally against each other (about the cylinder longitudinal axis) rotatable are.

For axially holding or fixing the counter-abutment part 11, a holder 15 seated on the cylinder 2 is provided. The holder 15 is formed from at least two axially spaced-apart, radially outwardly projecting projections 16, 17, between which the sleeve 14 is inserted. The projections 16, 17 run at least partially around the cylinder 2. The two arms of the second portion 8 of the stop member 6 are guided in the interrupted portions of the projections 16, 17 in the axial direction. The holder 15 with the projections 16, 17 is formed on a disposed between the counter-stop member 11 and the cylinder 2 intermediate sleeve 18, on which the counter-abutment member 11 is also rotatably mounted.

As in the case of the first embodiment, the second section 8 or the arms of the abutment part 6 extends in sections between the cylinder 2 and the counter-abutment part 11.

The invention is not limited to the embodiments described above and further embodiments are possible. For example, the counter-stop member 11 may be manually rotatable. The counter-abutment part 11 can also interact with a latching device with which the rotational positions of the counter abutment part 11 assigned to the respective abutment pairings can be locked. Such a latch can e.g. a preferably spring-loaded ball pressure piece, which can engage in corresponding, the stop pairings associated recesses in the counter-stop.

The cylinder-piston unit 1 may additionally comprise means for measuring the distance traveled piston and / or means for measuring the relative rotational position of the counter-abutment part 11, in particular in the form of an angle measuring device.

The solution according to the invention has proved particularly useful with pneumatically actuable cylinders, but all other types of cylinders are also encompassed by the invention.

For the sake of order, it should finally be pointed out that, for a better understanding of the structure of the cylinder-piston unit, these or their components have been shown partially unevenly and / or enlarged and / or reduced in size.

[0084] The object underlying the independent inventive features and solutions can be taken from the description. 8/15 Austrian Patent Office AT512 663 B1 2013-10-15

REFERENCE IDENTIFICATION 1 cylinder-piston unit 2 cylinder 3 piston rod 4 piston 5 stop mechanism 6 stop member 7 Section 8 Section 9 stop structure 10 stop structure 11 counter stop 12 limit stop 13 limit stop 14 sleeve 15 holder 16 projection 17 projection 18 intermediate sleeve 19 axis 20 cylinder longitudinal axis 21 connecting element 22 connecting element 23 Implementation 9/15

Claims (28)

Austrian Patent Office AT512 663 B1 2013-10-15 Claims 1. Cylinder-piston unit (1) whose piston (4) is connected to a piston rod (3) protruding from an end face of the cylinder (2) and which has a variably adjustable stroke limiting device in the form of a stop mechanism (5) which comprises a stop member (6) and a counter stop member (11), the stop member (6) being provided with a first portion (7) on a part of the piston rod (3) projecting from the cylinder (2) ) and having a second portion (8) extending outwardly along the cylinder (2) cooperates in a stop position with the counter-abutment portion (11), and wherein the counter-abutment portion (11) is axially retained with respect to the cylinder (2) is, and the counter-stop member (11) is rotatable relative to the stop member (6), said stop member (6) and counter-stop member (11) depending on the relative rotational position form different pairs of stops through which the path the piston rod (3) can be limited to different degrees, characterized in that the counter-abutment part (11) forms different limit stops (12, 13), which are each assigned to the different stop pairings. 2. Cylinder-piston unit according to claim 1, characterized in that the counter-abutment part (11) relative to the cylinder (2) is rotatable. 3. Cylinder-piston unit according to claim 1 or 2, characterized in that the counter-abutment part (11) on both of its end faces, which are axially spaced from each other with respect to the cylinder longitudinal axis (20) forms respective different limit stops (12, 13) such that the travel of the piston rod (3) can be limited to different degrees in both directions. 4. Cylinder-piston unit according to claim 3, characterized in that the counter-abutment part (11) is formed from two mutually rotatable sections, wherein one of the two end faces of the counter-abutment part (11) is formed on one of the two sections and the other end face of the counter-abutment part (11) is formed on the other portion. 5. Cylinder-piston unit according to one of the preceding claims, characterized in that the second portion (8) of the stop member (6) by at least one elongated arm is formed, which is substantially parallel to the longitudinal axis (20) of the cylinder (2 ). 6. Cylinder-piston unit according to one of the preceding claims, characterized in that the second portion (8) of the stop member (6) is formed by at least two substantially mutually parallel arms, which along opposite sides of the cylinder (2) run. 7. Cylinder-piston unit according to one of the preceding claims, characterized in that the second portion (8) of the stop member (6) has two with respect to the cylinder longitudinal axis (20) axially spaced, with the counter-stop member (11) cooperating stop structures (9 , 10) and that the counter-abutment part (11) at least partially in the region between the stop structures (9, 10) protrudes, so that the path of the piston rod (3) is limited in both directions. 8. cylinder-piston unit according to claim 7, characterized in that the stop structures (9, 10) are formed in the form of lugs which protrude in relation to the cylinder (2) radially outwardly. 9. cylinder-piston unit according to one of claims 2 to 8, characterized in that the counter-abutment part (11) surrounds the cylinder (2) or is arranged next to the cylinder (2). 10. Cylinder-piston unit according to one of the preceding claims, characterized in that the counter-abutment part (11) in the form of a cylinder (2) enclosing sleeve (14) is formed and about the longitudinal axis (20) of the cylinder (2) rotatable is. 10/15 Austrian Patent Office AT512 663 B1 2013-10-15 11. Cylinder-piston unit according to claim 10, characterized in that the different limit stops (12, 13) are formed by a step-shaped wall of the sleeve (14). 12. Cylinder-piston unit according to one of the preceding claims, characterized in that for axially holding the counter-abutment part (11) on the cylinder (2) seated holder (15) is provided. 13. Cylinder-piston unit according to claim 12, characterized in that the holder (15) of at least two axially spaced apart, radially outwardly projecting projections (16,17) is formed, between which the counter-abutment part (11) is inserted. 14. Cylinder-piston unit according to claim 13, characterized in that the projections (16, 17) at least partially run around the cylinder (2). 15. Cylinder-piston unit according to claim 13 or 14, characterized in that the second portion (8) of the stop member (6) by the projections (16, 17) is guided in the axial direction. 16. Cylinder-piston unit according to one of claims 12 to 15, characterized in that the holder (15) is formed on a between the counter-stop member (11) and the cylinder (2) arranged intermediate sleeve (18) on which the counter-abutment part (11) is rotatably mounted. 17. Cylinder-piston unit according to one of claims 2 to 9, characterized in that the counter-abutment part (11) about an axis of rotation (19) is rotatably arranged laterally spaced from the cylinder (2) and substantially parallel to the cylinder longitudinal axis (20 ). 18. Cylinder-piston unit according to claim 17, characterized in that the counter-abutment part (11) is designed as a drum whose longitudinal axis coincides substantially with its axis of rotation (19). 19. Cylinder-piston unit according to claim 18, characterized in that the limit stops (12) are formed on a front side of the drum as sector-wise graduations. 20. Cylinder-piston unit according to one of claims 17 to 19, characterized in that a lower portion of the cylinder (2) at a lower portion of the rotation axis (19) via a first connecting element (21) is connected and an upper portion of the Cylinder (2) at an upper portion of the axis of rotation (19) via a second connecting element (22) is connected. 21. Cylinder-piston unit according to claim 20, characterized in that in one of the connecting elements (22) has a passage (23) is provided, through which the stop member (6) is passed. 22, cylinder-piston unit according to one of the preceding claims, characterized in that the second portion (8) of the stop member (6) between the cylinder (2) and counter-abutment part (11). 23. Cylinder-piston unit according to one of the preceding claims, characterized in that the counter-abutment part (11) is manually rotatable. 24. Cylinder-piston unit according to one of the preceding claims, characterized in that the counter-abutment part (11) cooperates with a latching device, with which the respective stop pairings associated rotational positions of the counter-abutment part (11) can be locked. 25. Cylinder-piston unit according to claim 24, characterized in that the latching device comprises a preferably spring-loaded ball pressure piece. 11/15 Austrian Patent Office AT 512 663 B1 2013-10-15 26. Cylinder-piston unit according to one of the preceding claims, characterized in that the cylinder-piston unit (1) comprises a device for measuring the recirculated piston stroke. 27. Cylinder-piston unit according to one of the preceding claims, characterized in that the cylinder-piston unit (1) comprises means for measuring the relative rotational position of the counter-abutment part (11), in particular in the form of an angle measuring device. 28. Cylinder-piston unit according to one of the preceding claims, characterized in that the cylinder-piston unit (1) is pneumatically actuated. 3 sheets of drawings 12/15