Operating cylinder device with at least one operating cylinder unit with mechanical position safety and operating method

Abstract

In order to secure a reached extension position of a piston rod (22, 22) of an in particular multi stage operating cylinder device (100) with at least one operating cylinder unit (50) not only through the operating pressure in the cylinder (1, 1) of the operating cylinder unit (50) but additionally mechanically, a mechanical safety through interlocking safety elements (4a, b) in the interior of the operating cylinder device (100) is provided which is activated exclusively by the operating pressure in the first pressure cavity and disengaged by a pressure in a second operating cavity.

Claims

1. An operating cylinder device (100) including at least one multistage telescoping operating hydraulic cylinder unit (50) comprising per telescope stage (50.1, 50.2): a cylinder (21, 21) including a cylinder base (21c) at a rear end and an annular rod seal unit (5) that is attached in a circular opening at an open front end of a cylinder cavity (21a), a piston rod (22, 22) that is axially moveable and sealed tight through the annular rod seal unit (5) and which protrudes in outward direction over a portion of its length axially forward out of the cylinder (21, 21) and whose outer circumferential surface (22a) is configured as a smooth piston seal surface (22a) and contacts the annular rod seal unit (5), a first pressure cavity (1, 1) that is thus formed and sealable tight in an interior of the cylinder (21, 21) between the annular rod seal unit (5), the piston rod (22, 22) and the cylinder (21, 21) and which includes a first pressure cavity connection (1 a, 1a), a mechanical position safety (4) for an axial position of the piston rod (22, 22) relative to the cylinder (21, 21) by cooperating safety elements (4a, b), characterized in that at least one piston side safety element (4a) is arranged in a rear portion of the piston rod (22, 22), and at least one cylinder side safety element (4b) is arranged in the axial direction (10) in series at or in an inner circumferential surface (21a) of the cylinder (21, 21) axially remote from the annular rod seal unit (5), the at least one mechanical position safety (4) is a form locking position safety (4) which is provided by cooperation of the piston side safety elements (4a) being interlocking protrusions (4a) with the cylinder side safety elements (4b) being interlocking recesses (4b) in that the interlocking protrusions (4a) penetrate the interlocking recesses 4(b), with a precise fit, the interlocking protrusions (4a) are arranged at an outer circumference of the piston rod (22) and the interlocking recesses (4b) are arranged at an inner circumference of the cylinder (21) wherein the interlocking recesses (4b) are arranged at a uniform distance from each other in the axial direction (10) and/or plural interlocking recesses (4b) are arranged evenly spaced over a circumference at an axial position or an interlocking ring groove (4b) extends over the circumference at the axial position.

2. The operating cylinder device (100) according to claim 1, characterized in that the at least one piston side safety element provided as the at least one interlocking protrusion (4a) is movable in the radial direction (11) relative to the piston rod (22) between an interlocked position and an unlocked position, displaceable or pivotable and protrudes in the radial direction (11) at least in its interlocked position in an outward direction beyond an outer contour of the piston seal surface (22a), and/or the at least one cylinder side interlocking recess (4b) is arranged fixed in position at or in an inner circumferential surface (21a) of the cylinder (21, 21).

3. The operating cylinder device (100) according to claim 1, characterized in that the at least one piston side interlocking protrusion (4a) is arranged in the first pressure cavity (1, 1) and a radial outer surface of the interlocking protrusion (4a) that is arranged in the first pressure cavity (1, 1) is greater than a radial inner surface of the interlocking protrusion (4a) that is arranged in the first pressure cavity (1, 1), in that a support protrusion (4a3) protrudes radially inward from a radial inner surface of each piston side interlocking protrusion (4a) and is supported in a support recess (13) in a radial direction sealed tight so that a freely accessible radial inner face of the support protrusion (4a3) is not directly connected with the first pressure cavity (1, 1).

4. The operating cylinder device (100) according to claim 1, characterized in that the piston rod (22) includes a piston end piece (6) at a free end wherein the interlocking protrusions (4a) are attached movable in the radial direction (11), radially extensible or pivotable, at a rear end (6a) or outer circumference of the piston end piece.

5. The operating cylinder device (100) according to claim 4, characterized in that the interlocking protrusions (4a) are configured as interlocking segments (4a) that extend over a portion of the circumference, and/or the interlocking protrusions (4a) are arranged in a receiving groove (7), of the piston end piece (6) from which they protrude in the radial direction.

6. The operating cylinder device (100) according to claim 5, characterized in that the interlocking segments (4a) are secured in a form locking manner in a receiving ring groove (7) in an outer circumference of the piston end piece (6) and secured against a displacement in the circumferential direction (12), in that a support protrusion (4a1) protrudes radially inward from a radial back side of each interlocking segment (4a) and is radially supported in a support recess (13).

7. The operating cylinder device (100) according to claim 6, characterized in that a supply cavity (14) is provided in the interior of the piston rod (22, 22) of the piston end piece (6), and all support recesses (13) are connected with the supply cavity (14) and form a second pressure cavity (2, 2), the second pressure cavity (2, 2) is connected with a second pressure cavity connection (2a, 2a) in the outer surface of the enveloping cylinder (21, 21) through a connection cavity (15).

8. The operating cylinder device (100) according to claim 7, characterized in that one of at least two supply tubes (31, 32) that are movable axially sealed tight inside each other, thus telescopable, are attached sealed tight at a rear free end of the piston rod (22, 22) protruding backward from the end piece (6) in the axial direction (10) and on the other hand side protruding forward in the axial direction (10) from a cylinder base (21c) of a cylinder (21, 21) surrounding the cylinder base, and the connection cavity (15) is enveloped by the supply tubes (31, 32) so that a second pressure cavity (2, 2) is provided by the supply cavity (14) and the connection cavity (15) wherein the second pressure cavity (2, 2) is flow disconnectable from the first pressure cavity (1, 1) and radially enveloped by the first pressure cavity (1, 1).

9. The operating cylinder device (100) according to claim 7, characterized in that in the multistage operating cylinder unit (50) the first pressure cavities (1, 1) are connected with each other, and/or the second pressure cavities (2, 2) are connected with each other.

10. The operating cylinder device (100) according to claim 7, characterized in that the first pressure cavities (1, 1) and the second pressure cavities (2, 2), each pressure cavity (1, 1, 2, 2) is connected with a pressure generator, through an adjustable throttle (23, 24) and with a check valve that is adjustable with respect to its closing pressure and/or unlockable, and a control is provided which controls each of the pressure generators and/or each adjustable throttle (23, 24) and each adjustable and/or unlockable check valve.

11. The operating cylinder device (100) according to claim 10, characterized in that at least one pressure sensor is provided which measures a pressure in at least one of the pressure cavities (1, 1, 2, 2) and communicates through signals with the control and/or a differential pressure sensor is provided which measures a pressure difference between the first pressure cavity (1, 1) and the second pressure cavity (2, 2) of each stage of the operating cylinder unit.

12. The operating cylinder device (100) according to claim 11, characterized in that at least one distance sensor is provided which measures an extension length (L, L) of the piston rod (22, 22) relative to the cylinder (21, 21) and the pressure sensor is signal connected with the control, and/or the second pressure cavity (2, 2) is connected through an adjustable pressure relief valve (28) with a tank (27).

13. The operating cylinder device (100) according to claim 12 with at least one operating cylinder unit (50) that includes a mechanical safety for the axial position of the extended connecting rod (22, 22) relative to its cylinder (cylinder (21, 21) of the operating cylinder device (100), characterized in that for extending the piston rod (22, 22) from the cylinder (21, 21) the first pressure cavity (1, 1) is loaded with a lifting pressure (p1) which loads the piston (22, 22) with an extension force which is greater than a sum of an opposite force impacting the piston (22, 22) and of internal friction forces of the operating cylinder unit (50) until a predetermined nominal extension length is reached, and thus A1: either the second pressure cavity (2, 2) is open towards the tank (27) so that fluid can flow from the tank into the second pressure cavity (2, 2) that expands during expansion so that the fluid can be pulled in, A2: or the second pressure cavity (2, 2) is closed towards the tank (27) but connected with the first pressure cavity (1, 1) during the extension, connected in a highly throttled manner.

14. The operating cylinder device (100) according to claim 13, characterized in that for a controlled retraction of the piston rod (22, 22) that is loaded with an opposite force that is oriented in the retraction direction into the cylinder (21, 21) initially a function according to one of the steps A1 or A2 is performed, subsequently the interlocking pressure (P3) and the optionally provided interlocking force (F3) are selected in relationship to the lifting pressure (P1) provided in the first pressure cavity (1, 1) so that a resultant force is created that impacts the safety element (4a) wherein the resultant is oriented in a radially inward direction, in that a throttle (23) in the pressure cavity connection (1a) to the first pressure cavity (1, 1) is set accordingly, wherein this is maintained until the piston rod (22, 22) has reached the completely retracted extension length (L).

15. The operating cylinder device (100) according to claim 14, characterized in that the retraction velocity and/or the pressure in the second pressure cavity (2, 2) is measured and the pressure cavity connection (2a, 2a) of the second pressure cavity (2, 2) is closed partially or entirely when a predetermine threshold value is exceeded.

16. The operating cylinder device (100) according to claim 12, including plural operating cylinder units (50), characterized in that the control controls all operating cylinder units (50), or all pressure generators, or all adjustable valves, all adjustable throttles (23, 24), all adjustable and/or unlockable check valves and all adjustable pressure relief valves (28), and either all first pressure cavities (1, 1) of all operating cylinder units (50) are connected in an interrupt able manner with a first distribution cavity (51) which is connected with a first pressure generator and all second pressure cavities (2, 2) of all operating cylinder units (50) are connected in an interruptible manner with a second distribution cavity (52) that is connected with a second pressure generator, or all pressure cavities (1, 1, 2, 2) of all operating cylinder units (50) are connected in an interruptible manner with a first distribution cavity (51) that is connected with a pressure generator.

17. The operating cylinder device (100) according to claim 10, characterized in that a mechanical safety for the axial position of the extended piston rod (22, 22) is provided in that a pressure in the first pressure cavity is reduced from the lifting pressure (p1) to a lowering pressure (p2) which loads the piston rod (22, 22) with a force which is smaller than a sum of an opposite force impacting the piston (22, 22) and of internal friction forces of the operating cylinder unit (50) until the piston (22, 22) is axially retracted far enough so that the safety elements (4a, b) that cooperate through form locking can interlock with each other, the at least one interlocking protrusions (4a) can interlock in one of the interlocking protrusions (4b) and the interlocking is caused, and/or a hydraulic safety of the axial position of the extended piston rod (22, 22) is provided in that reaching the predetermined nominal extension length the unlockable check valves of each of the two pressure cavities (1, 1) and (2, 2) are closed by turning the pressure supply off so that the two pressure cavities with the operating medium enclosed therein are closed.

18. The operating cylinder device (100) according to claim 17, characterized in that for securing an interlocking of the safety element (4a) of the interlocking protrusion (4a) of the interlocking segment (4a) is caused during interlocking in that a radial outside as well as a portion of the radial inside of the radially movable safety element (4a), the first pressure cavity (1, 1) is loaded with the lowering pressure (P2), and a remaining portion of the radial inside of the safety element (4a), the second pressure cavity (2, 2) is loaded with an interlocking pressure (p3) and optionally with an additional mechanically induced interlocking force (F3), wherein the the interlocking pressure (p3) and the optionally provided interlocking force (F3) are selected relative to the lower pressure (p2) so that a resulting force is provided that impacts the safety element (4a) in a radial direction wherein the resulting force is oriented in a radially outward direction when the interlocking force (F3) is provided the interlocking pressure (p3) is selected higher than the lowering pressure (p2).

19. A lifting device (60) with an operating cylinder unit (50) of an operating cylinder device (100), according to claim 1, characterized in that the operating cylinder unit (50) with a piston rod (22) that is extendable in an upward direction from a cylinder (21) is arranged in a base frame (61) of the lifting device (60), wherein support legs (62a, b, c,) extend in a radially outward and downward direction from the lifting device (60) wherein the support legs are braced with their respective radially outward support end by a horizontal strut (63a, b, c) relative to the cylinder (21) and sit on the ground, a display device (40) is arranged at each lifting device (60).

20. The lifting device (60) according to claim 19, characterized in that a sensor piston (42b) is arranged in an elevation range below an attachment of one of the support legs (62) at the cylinder (21) on an outside of the cylinder (21), in top view below one of the support legs (62), between the support leg (62) and its horizontal strut (63).

21. The lifting device (60) according to claim 19, characterized in that an LED of the display device is arranged between 1 m and 2 m elevation at an outside of the cylinder (21) at plural circumferential locations.

22. The lifting device (60) according to claim 19, characterized in that the display device (40) is received in a recess of a valve block (46) of the operating cylinder unit (50), the valve block (46) is bolted directly at an outside of the cylinder (21) of the operating cylinder unit (50) and the valve block (46) extends on a side of the display device (40) which is on an outside with reference to a longitudinal center (10) of the operating cylinder unit (50).

23. The lifting device (60), according to claim 19, characterized in that a respective hydraulic safety element is arranged in the cylinder (21) of the operating cylinder unit (50) in connection conduits between the pressure cavities (1, 2) and the valve block (46), the display device (40) is flow connected with portions of the connection conduits between the pressure cavities (1, 2) and the valve block (46).

24. An operating cylinder device (100) including at least one multistage telescoping operating hydraulic cylinder unit (50) comprising per telescope stage (50.1, 50.2): a cylinder (21, 21) including a cylinder base (21c) at a rear end and an annular rod seal unit (5) that is attached in a circular opening at an open front end of a cylinder cavity (21a), a piston rod (22, 22) that is axially moveable and sealed tight through the annular rod seal unit (5) and which protrudes in outward direction over a portion of its length axially forward out of the cylinder (21, 21) and whose outer circumferential surface (22a) is configured as a smooth piston seal surface (22a) and contacts the annular rod seal unit (5), a first pressure cavity (1, 1) that is thus formed and sealable tight in an interior of the cylinder (21, 21) between the annular rod seal unit (5), the piston rod (22, 22) and the cylinder (21, 21) and which includes a first pressure cavity connection (1a, 1a), a mechanical position safety (4) for an axial position of the piston rod (22, 22) relative to the cylinder (21, 21) by cooperating safety elements (4a, b), characterized in that at least one piston side safety element (4a) is arranged in a rear portion of the piston rod (22, 22), at least one cylinder side safety element (4b) is arranged in the axial direction (10) in series at or in an inner circumferential surface (21a) of the cylinder (21, 21) axially remote from the annular rod seal unit (5), the at least one mechanical position safety (4) is a form locking position safety (4) which is provided by cooperation of the piston side safety elements (4a) being interlocking protrusions (4a) with the cylinder side safety elements (4b) being interlocking recesses (4b) in that the interlocking protrusions (4a) penetrate the interlocking recesses (4b), with a precise fit, the interlocking protrusions (4a) are arranged at an outer circumference of the piston rod (22) and the interlocking recesses (4b) are arranged at an inner circumference of the cylinder (21), the piston rod (22) includes a piston end piece (6) at a free end wherein the interlocking protrusions (4a) are attached movable in the radial direction (11), radially extensible or pivotable, at a rear end (6a) or outer circumference of the piston end piece, the interlocking protrusions (4a) are configured as interlocking segments (4a) that extend over a portion of the circumference, the interlocking segments (4a) are secured in a form locking manner in a receiving ring groove (7) in an outer circumference of the piston end piece (6) and secured against a displacement in the circumferential direction (12), and in that a support protrusion (4a1) protrudes radially inward from a radial back side of each interlocking segment (4a) and is radially supported in a support recess (13).

25. A lifting device (60) with an operating cylinder unit (50) of an operating cylinder device (100) including at least one multistage telescoping operating hydraulic cylinder unit (50) comprising per telescope stage (50.1, 50.2): a cylinder (21, 21) including a cylinder base (21c) at a rear end and an annular rod seal unit (5) that is attached in a circular opening at an open front end of a cylinder cavity (21a), a piston rod (22, 22) that is axially moveable and sealed tight through the annular rod seal unit (5) and which protrudes in outward direction over a portion of its length axially forward out of the cylinder (21, 21) and whose outer circumferential surface (22a) is configured as a smooth piston seal surface (22a) and contacts the annular rod seal unit (5), a first pressure cavity (1, 1) that is thus formed and sealable tight in an interior of the cylinder (21, 21) between the annular rod seal unit (5), the piston rod (22, 22) and the cylinder (21, 21) and which includes a first pressure cavity connection (1a, 1a), a mechanical position safety (4) for an axial position of the piston rod (22, 22) relative to the cylinder (21, 21) by cooperating safety elements (4a, b), wherein at least one piston side safety element (4a) is arranged in a rear portion of the piston rod (22, 22), and at least one cylinder side safety element (4b) is arranged in the axial direction (10) in series at or in an inner circumferential surface (21a) of the cylinder (21, 21) axially remote from the annular rod seal unit (5), wherein the lifting device (60) is characterized in that the operating cylinder unit (50) with a piston rod (22) that is extendable in an upward direction from a cylinder (21) is arranged in a base frame (61) of the lifting device (60), wherein support legs (62 a, b, c,) extend in a radially outward and downward direction from the lifting device (60) wherein the support legs are braced with their respective radially outward support end by a horizontal strut (63a, b, c) relative to the cylinder (21) and sit on the ground, a display device (40) is arranged at each lifting device (60).

Description

(1) The invention is subsequently described in more detail with drawing figures, wherein:

(2) FIG. 1a illustrates a two stage operating cylinder device in completely retracted position of both telescope stages in a longitudinal sectional view, thus cut in an axial direction along the line I.-I. of FIG. 2a.

(3) FIG. 1b illustrates the operating cylinder device according to FIG. 1a in a completely extended condition of both telescope stages,

(4) FIG. 1c illustrates a blown up detail of FIG. 1b,

(5) FIG. 2a illustrates a face view of the operating cylinder device according to FIG. 1a through from a front in a direction II>a,

(6) FIGS. 2b, c illustrate sectional views along the line II. b or II. c according to FIG. 1a, the center tube of the operating cylinder unit 50 in a longitudinal sectional view in a face front view;

(7) FIGS. 3a, b illustrate a cylinder configured as an individual component in a longitudinal sectional view and in a front view;

(8) FIG. 4 illustrates a piston end piece in a perspective view with interlocking segments arranged thereon;

(9) FIG. 5 illustrates the interlocking segments according to FIG. 4, however without the piston end piece,

(10) FIG. 6 illustrates a pressure distribution in the two pressure cavities of the operating cylinder unit according to the preceding figures in various operating positons.

(11) FIGS. 7a, b illustrate a display device that is installed at the operating cylinder unit in a side view and from above, partially cut.

(12) FIGS. 8a, b illustrate the sensor piston with only one exemplary piston protrusion in both end positions in a sensor cylinder that is cut in the longitudinal direction.

(13) FIGS. 1a and 1b illustrate an operating cylinder device 100 in retracted condition and extended condition comprising a two stage operating cylinder unit 50 typically operated as a hydraulic cylinder unit 50 and in particular an attachment device 51 for attaching the operating cylinder unit 50 at an adjacent component.

(14) As illustrated in the front view of FIG. 2a and in particular in the section al views of FIGS. 2b, c the operating cylinder unit 50 is configured rotation symmetrical about the longitudinal center 10 so that most of its components, the cylinders 21, 21 and the piston rod 22, 22 have a circular outer contour and/or inner contour.

(15) In this case the attachment device 51 is attached at the outer most cylinder 21 in the radial direction and is made from three attachment plates 51a, b, c extending there from in the radial direction thus in the transversal direction 11 and extending in the axial direction 10 wherein pass through bore holes are provided in the attachment plates 51 a, b, c that are offset in the axial direction through which the attachment plates can be bolted to an adjacent component.

(16) In this outer most cylinder 21 of the radially outermost telescoping stage 50.2 is as usual for multi stage operating cylinder units 50 an outer piston 22 is displace able in the axis direction 10 wherein the outer piston 22 simultaneously forms the inner piston 21 for the radially interior telescoping stage 50.1 and in which in turn an inner piston 22 is move able in the axial direction 10.

(17) It is essential for the invention that the pistons 22, 22 are interlockable relative to their respective cylinder 21, 21 in both telescoping stages 50.1 and 50.2 respectively in a plurality of interlocking position along the axial direction in a form locking manner as a position safety 4 illustrated best in detail in the blow up of FIG. 1c.

(18) For this purpose the rear portion of each cylinder 22, 22 includes interlocking elements that are extensive beyond its outer circumference an then are provided as interlocking segments 4a extending over a portion of the circumference which can interlock in an extended condition in corresponding interlocking recesses 4b a plurality of which is arranged behind one another in the radially opposite inner circumferential surface 21a of the surrounding cylinder 21, 21 in the axial direction 10. The interlocking recesses 4b are in this case advantageously configured as circumferentially extends interlocking ring grooves 4b.

(19) In order to facilitate fabrication the interlocking segments 4a are respectively radially supported in a piston end piece 6 which is attached tight at a rear end of the otherwise tubular outer piston rod 22 so that it forms an inner cylinder 21 that is open at a front face and that receives the next inner telescoping stage 50. 1. By the same token the piston end piece 6 is attached at the radially interior piston rod 22 which is in this case not configured hollow in the pass through direction but only includes axial bore holes from both faces which protrude deeply in the axial direction into the piston rod 22.

(20) Also the outer cylinder 21 is not integrally produced in one piece but has a tubular center element which is also closed tight at its rear end by a cylinder end piece 6* that is attached tight thereon.

(21) The pistons 22, 22 are respectively operated as plungers, thus piston rods 22, 22 relative to the cylinders 21, 21 enveloping them radially wherein each cylinder 21, 21 includes annular circumferential rod sealing units proximal to its open face end respectively arranged in its inner circumferential surface 21a. The rod seal units 5 respectively include at least one annular circumferential elastic seal and axially adjacent thereto typically combined into one component, the seal sleeve 29 at least one so called support band that is also annular circumferential and supports and centers the piston rod 22, 22 wherein both slide ably contact the smooth outer circumferential surface 22a after respective piston rod 22, 22 functioning and piston seal surface 22a wherein the sliding movement is facilitated in the axial direction 10.

(22) For this purpose the respective cylinder 21, 21 is respectively provided with a seal sleeve 29 that is attached tight at the tubular center element 21d, 21d at its front end, in particular sealed tight wherein the an inner circumferential surface of the tubular center element forms part of the inner circumferential surface 21a, or 21a of the respective cylinder 21, 21.

(23) Advantageously the inner circumferential surface of the seal sleeve 29 respectively includes plural ring grooves that are respectively offset in the axial direction 10 in which support bands and seals are arranged that protrude radially inward beyond the inner circumferential surface and which are not illustrated in the drawing figures.

(24) Thus, a first pressure cavity 1 is formed in the first radially inner telescoping stage 50.1, wherein the first pressure cavity 1 is radially defined by the inner piston rod 22 and which is enveloped on the radial outside by the inner cylinder 21, wherein the first pressure cavity 1 is defined in the axial direction 10 by the rod sealing unit 5 at a front end of the cylinder 21 and the cylinder base 21c configured as the piston end piece 6 which is attached tight at the rear closed end of the cylinder 21 as evident from FIG. 1b.

(25) The center element 21d of the cylinder 21 of the radially interior first telescope stage 50.1 is illustrated in FIG. 3a in a longitudinal sectional view and in FIG. 3b in a front view.

(26) Analogously a first pressure cavity 1 is formed in the radially outer second telescope stage 50.2 which is in turn defined in the radial direction by the piston rod 22 and the enveloping cylinder 21 and in the axial direction 10 by the rod sealing unit 5 arranged at the cylinder 21 at the forward open face end of the outer cylinder 21 and at a rear end by the cylinder end piece 6 attached tight at the center element 21d of the cylinder 21.

(27) Theoretically the operating cylinder unit 50 could also be installed in a reverse manner and outward protruding portion of the innermost piston rod 22 instead of the outer most cylinder 21 in the illustrated condition can form the fixed component of the operating cylinder unit 50 that is arranged at an adjacent component in this case the attachment device 51 for attaching the operating cylinder unit 50 at an adjacent component would be attached the inner most piston rod 22 that extends freely out of the enveloping cylinder. This solution however has a number of disadvantages and is only used in exceptional applications.

(28) The piston end pieces 6, 6 and the interlocking recesses 4a arranged thereon and provided as interlocking recesses 4a do not provide a seal between the piston where they are attached and the enveloping cylinder so that the respective first pressure cavity 1, 1 extends in the axial direction 10 in front and behind the piston end piece 6.

(29) Each of the two first pressure cavities 1, 1 includes a first pressure cavity connection 1a, 1a through which it can be supplied with the operating medium, typically a hydraulic medium and loaded with pressure.

(30) In the radially outer first pressure cavity 1 the first pressure cavity connection 1a is an inlet bore hole which extends through the cylinder end piece 6 and which is connectable on its outside with a non-illustrated pressure source.

(31) The first pressure cavity connection 1a is provided for example as an axial pass through bore hole 30 which extends through the piston end piece 6 of the radially outer second telescope stage 50.2 and which connects the two first pressure cavities 1, 1 with one another.

(32) Thus it is evident that the required mechanical processing of the inner circumferential surfaces 21a of the cylinders 21, 21 and on the other hand side of the outer circumferential surfaces 22a of the pistons 22, 22 which are partially identical is facilitated by the tubular shape of the center elements that is open on both sides.

(33) On the one hand side the dual side face accessibility facilitates fabricating the ring grooves configured as interlocking recesses 4b which are arranged axially besides a short starting piece on both sides over the entire axial length 10 at a distance from each other that is as small as possible and provided with a cross section contour that is fabricated very precisely.

(34) On the other hand side this also facilitates fabricating an outer circumferential surface 22a at a piston rod 22, 22 wherein the outer circumferential surfaces acts as a piston sealing surface.

(35) The inner cross section is slightly enlarged compared to the center element at a face end that is illustrated on the left side of FIG. 3a in order to facilitate inserting the seal sleeve 29 at this location and the shoulder in the inner circumferential surface 21a at a right end of the tubular center element 21d is used for tight application of a piston end piece 6 at this location as illustrated in FIGS. 1a, b.

(36) The cross sectional shape of each of the interlocking recesses 4b and the cross sectional shape of the outer contour of the interlocking elements 4a which form a segment of a circular arc corresponding to the circular arc of the annular interlocking recesses 4b are illustrated best in FIG. 1c together with the perspective illustrations of the interlocking segments 4a in FIG. 5.

(37) The annular interlocking recesses 4b are thus always arranged at a constant axial distance 19 from each other.

(38) Here it is evident that each the interlocking annular grooves 4b has a cross section that includes a front flank 4b1 at an end that is in front in the axial direction 10 wherein the front flank is oriented at a slant angle to the axial direction 10 and approaches the axial direction 10 towards the longitudinal center 10 in the extension direction 10.

(39) A rear flank 4b2 of each annular interlocking groove 4b is on the other hand side includes a surface, in particular an annular surface that is orthogonal to the axial direction 10.

(40) The outer end of the rear flank 2b2 and rear end of the front flank 4b1 are connected by a center flank that extends in particular parallel to the axis direction 10.

(41) An outer contour of each of the interlocking segments 4a is configured analogous to a front flank 4a1, a center element and a rear flank 4a2 which advantageously coincides with respect to a slant angle of the front flank 4a with the inclination of the front flank 4b1 of the circular interlocking groove 4b.

(42) Also the dimensions are selected so that the interlocking segment 4a can interlock in one of the annular interlocking recesses 4b.

(43) All recited flanks are circular ring shaped or circular segment shaped on a side of the interlocking segments 4a, due to the rotation symmetrical configuration in the axis direction 10 as evident in particular from FIG. 5.

(44) In the illustrated embodiment each piston end piece 6, 6 includes 6 interlocking segments 4a in a receiving ring groove 7 that is fabricated in its outer circumference wherein the interlocking segments are evenly distributed over a circumference and precisely fit into the receiving ring groove 7 with respect to axial and radial extension so that the interlocking segments are supported by the ring groove and can penetrate into the ring groove so that they so not protrude radially beyond an outer circumference of the piston end piece 6, 6.

(45) As illustrated in FIGS. 5 and 1a, b a cylindrical support protrusion 4a3 protrudes from a radially inner back side of each of the interlocking segments 4a that is fixed at the interlocking segment and thus protrudes radially inward and is supported tight in the radial direction in a corresponding cylindrical support recess 13 of the piston end piece 6, 6, e.g. in that an O-ring seal is inserted in the annular groove that is visible in the outer circumference of the support protrusions 4a3.

(46) The radially extending support recesses 13 penetrate the annular or sleeve shaped piston end pieces 6, 6 from an inside out and are thus connected with one another through its central inner cavity 6c which penetrates the piston end piece 6, 6 from its rear end 6a to its front end 6b due to its sleeve shape.

(47) A respective compression spring 8 is also arranged at a radially inward oriented back side of each of the interlocking segments 4a on both sides adjacent to the support protrusion 4a3, wherein the compression spring acts in the radial direction and is supported with its inner free end at the base of the receiving ring groove 7 so that the annular segments 4a are loaded in a radially outward direction.

(48) Without further force impact in a piston end piece 6, 6 whose interlocking segments are arranged at an axial position of an external enveloping interlocking ring groove 4b. The interlocking segments 4a would engage the enveloping annular interlocking recess 4b due to a force of the springs 8 as evident also in the cross sectional illustration of FIGS. 2b, 2c which illustrate this interlocked condition for the radially inner first telescoping stage 50. 1 (FIG. 2b) and on the other hand side for the radially outer second telescoping stage 50.2 (FIG. 2c).

(49) In practical applications, however, the interlocking segments 4a are not only pressed radially outward by a force of the springs 8 but in particular by pressure loading of the inner cavity 6c of the piston end piece 6 which thus also impacts a rear free face of each of the support protrusions 4a3 when the inner cavity 6c which acts as a supply cavity 14 for the support recesses 13 of the piston end piece 6, 6 is loaded with pressure.

(50) This can be provided in that the inner cavities 6c of the piston end pieces 6 as evident form FIG. 1b form a component of a respective second radially inward pressure cavity 2, 2 which are also connected with each other.

(51) Thus, the inner cavities 6c of the two piston end pieces 6 are connected pressure tight with each other in that a telescope tube arrangement is provided between the two of them which telescope tube arrangement extends in the axial direction and includes a supply tube 32 that is movable tight therein, wherein a first supply tube is attached tight at a piston end piece 6 and leads into its inner cavity 6c and thus into its supply cavity 14 and the other is attached analogously in the piston end piece 6 and terminates in its inner cavity 6c and supply cavity 14.

(52) Between the rear end 6a of the axially rear piston end piece 6, 6 and a axial pass through bore hole of the cylinder end piece 6* another telescope tube arrangement is provided which includes an outer supply tube 31 and a sealed inner supply tube 32 supported therein and connected with a connection opening in the outside of the cylinder end piece 6 which forms the second pressure cavity connection 2a for this second pressure cavity 2.

(53) The second pressure cavity connection 2a and the two telescope tube arrangements 31, 32, 31, 32 are advantageously centrally arranged, thus concentric to the longitudinal center 10.

(54) The piston end piece 6 that is in front in the axial direction 10 could also be closed at the front end 6b and this piston end piece 6 cannot be sleeve shaped but has to be pot shaped, but the sleeve shape is selected for fabrication reasons and the piston end piece 6 is introduced tight, in particular threaded into a dead hole that is introduced into a rear face of the axially inner piston 22.

(55) The dead hole that is visible in FIG. 1a and extends from the front face of the inner piston 22, however is merely a mounting option for an adapter part that is not illustrated in the drawing figures and applicable to a front end of the piston rod 22 in order to adapt to various interfaces of the loads to be received.

(56) Thus, the second pressure cavity 2 that is in front in the axial direction and includes essentially the inner cavity 6c of the forward piston end piece 6 and the dead hole in the rear end of the piston rod 22 is connected through a connection cavity 15 adjoining its rear second pressure connection 2a which is formed by the inner space of the first telescope tube arrangement 31+32 with the rear second pressure cavity 2 which is essentially formed by the inner space 6c of the rear piston end piece 6 and this in turn is connected through another connection cavity 15 formed by the inner cavity of the second telescope tube arrangement 31+32 with the second pressure cavity connection 2a.

(57) The second pressure cavity connection 2a of the forward first pressure cavity 2 is formed by the outlet of the connection cavity 15 in the forward piston end piece 2.

(58) Thus, the continuous radial inner second pressure cavity 2, 2 can be supplied with pressure through the second pressure cavity connection 2a in the outside of the piston end piece 6 and the continuous first pressure cavities 1, 1 can be supplied with pressure through the at least one first pressure cavity 1a that is illustrated in the outer circumferential surface of the cylinder end pieces 6.

(59) This can be used to hydraulically extend the piston cylinder unit 50 and to retract through the load and thus to interlock the piston rods 22, 22 at one of the annular interlocking recesses 4b of the respectively adjacent radially enveloping cylinder 21, 21 in a form locking manner, wherein the pressure conditions prevailing in the individual operating conditions are illustrated in FIG. 6.

(60) FIG. 6 illustrates for the individual pressure cavities 1, 1 on the one hand side and 2, 2 on the other hand side a pressure diagram from start of operations through lifting and securing of a load resting on the operating cylinder device 100 and thus the operating cylinder unit 50 until the operating cylinder unit 100 is shut down.

(61) Thus, idle pressure p0 is the pressure that has to be provided in the first pressure cavity 1, 1 in order to keep a load vertically stable that rests on the operating cylinder unit 50 without mechanical position safety thus to neither lift the load any further or lower it any further.

(62) Initially the load contact surface, typically an upper end of the vertically arranged operating cylinder unit is distance between the load L to be lifted.

(63) Approaching load pick up point:

(64) Therefore the first pressure cavity 1, 1 is loaded initially with a very small contact pressure P3 which suffices to compensate the tare weight of the telescope stages and the inner friction and to extends the first rod slowly without load, for example three bar and thus extended without load until the load contact surface of the operating cylinder unit 50 contacts the load.

(65) Thus, the pressure in the second pressure cavity 2, 2 is kept lower and thus low enough so that the interlocking protrusions, in particular the interlocking segments 4a are with respect to the receiving ring groove in the radially inward moved deactivated position and when springs 8 are provided also in view of their spring force.

(66) The described approaching of the load receiving point is performed for plural operating cylinder units 50 in sequence with all typically three operating cylinder units 50 which shall be used for horizontal synchronous lifting of the load.

(67) Extension (load lifting):

(68) After all, typically three operating cylinder units 50 which shall be used for horizontal synchronous lifting of the load have contacted the load L at its respective receiving point loading lifting can be commenced.

(69) The subsequent method description typically relates to 3 operating cylinder units 50 that provide a synchronous vertical movement of the load that is to be kept horizontal.

(70) It is appreciated that the method steps subsequently described for an operating cylinder unit 50 have to be performed in parallel and synchronously with all operating cylinder units 50 that contribute to the horizontal, vertical movement of the load.

(71) The pressure in the first pressure cavity 1, 1 is increased to a lifting pressure p1 which is higher than the idle pressure p0 and this lifting pressure p1 is maintained until the load is lifted to the desired height. The fine adjustment of the lifting pressure p1 determines the lifting velocity.

(72) The pressure in the second pressure cavity 2, 2 remains in any case lower than the lifting pressure P1, in particular lower than the idle pressure p0 and in particular also lower than the contact pressure p3, advantageously at the same level as the base pressure p4 which was already provided in the second pressure cavity 2, 2 when contacting the load.

(73) Either the load is lifted to an axial lifting position which is in particular approximately 20 mm above the intended nominal lifting height and/or a difference that is less than the distance 9 of the interlocking recesses 4b that are adjacent to each other in the axial direction 10.

(74) Alternatively all telescope stages, in the instant embodiment 2 telescope stages are extended until they reach their inner mechanical end stop, namely the inner lower annular edges of the seal sleeves, 29, thus to the maximum extended position.

(75) When a nominal lifting height shall be approached which shall not be secured by mechanical interlocking in a form locking manner and thus the function of the unlockable check valves shall be used. The nominal lifting height can be approached precisely before switching off and the subsequently described procedures of interlocking securing and unlocking before lowering two the nominal lifting height can be omitted.

(76) This method simplification is in particular owed to the fact that unintentional pressure drop in the first pressure cavity which controls lifting and lowering of the load automatically triggers the form locking interlocking through hydraulic extension of the interlocking protrusions into the next interlocking recesses in the second pressure cavity through pressure increase in the second pressure cavity due to its volume reduction. The second pressure cavity is completely enveloped by the first pressure cavity. Damaging the second pressure cavity through external influences is therefore excluded.

(77) Interlocking:

(78) Since all telescope stages 50.1 and 50.2 of the operating cylinder unit 50 shall be interlocked in a form locking manner at the nominal lifting height the at least one piston rod 22, 22 is slightly retracted again from this condition in that the pressure in the operating cavity 1, 1 is lowered until slightly below the idle pressure p0 while the pressure in the second pressure cavity 2, 2 is increased to the interlocking pressure which causes a radial extension of the interlocking segments 4a and which is for this purpose advantageously also significantly above current pressure in the first pressure cavity 1, 1.

(79) Thus, the at least one piston rod 22, 22 is slightly retracted until the radially outward loaded interlocking segments 4a of the piston rods 22, 22 interlock in the next interlocking recess 4b in retraction direction.

(80) Secured:

(81) As soon as this is achieved which can be advantageously monitored automatically by corresponding sensors the pressure in the operating space 1, 1 can be lowered, advantageously down to 0 in the condition that is reached now and secured in a form locking manner.

(82) It is only important that the pressure in the pressure cavity 2 is kept high enough which can be kept under the interlocking pressure P5 so that the interlocking elements 4a are still loaded in the radially outward direction also in view of the springs 8 that are possibly provided and/or the friction loses and adhesion friction between the safety elements 4a and the piston end piece 6.

(83) Thus, advantageously the pressure in the pressure cavity 2, 2 in the secured condition is above the pressure in the first pressure cavity 1, 1. The supply cavities of the two pressure cavities 2, 2 and 1, 1 are then advantageously closed by the unlockable check valves that are provided according to the invention. The pressure generation can then be cut off.

(84) Unlocking:

(85) When the condition of supporting the load based on form locking interlocking shall be terminated initially the interlocking segments 4a have to be unlocked from the interlocking recesses 4b for this purpose, thus before retracting the at least one piston rod 22, 22 so that the piston cylinder unit 50 is disengaged from the load.

(86) After the pressure generation is turned on again the unlockable check valves open automatically and facilitate pressure oil supply to the first and second pressure cavity.

(87) In order to remove the contact pressure in axial direction between the rear flank 4a2 and the corresponding rear flank 4b2 of the interlocking recess 4b the at least one piston rod 22, 22; is initially extended a little more.

(88) Thus, the pressure in the first pressure cavity 1, 1 is raised to a lifting pressure above the idle pressure P0 which furthermore has to be high enough so that forces impacting the interlocking segment 4a from a radial outside thus from the first pressure cavity 1, 1 are greater than all forces impacting from the radial inside, thus from the second inner pressure cavity 2, 2 which can also include the force of the springs 8 besides the pressure in the second pressure cavity 2, 2.

(89) Advantageously the pressure in the second pressure cavity 2, 2 is set to the safety pressure P4 that is much lower than the idle pressure P0.

(90) Retracting (lowering):

(91) As soon as the safety elements 4a are retracted to the radially retracted deactivated position the pressure in the first pressure cavity 1, 1 is lowered for retracting the piston rods 22, 22 to a lowering pressure P2 below the idle pressure P0. The value of the lowering pressure P2 is selected as a function of the desired lowering speed.

(92) In this condition it only has to be assured that a resulting force is applied in a radially inward direction upon the interlocking segments 4a also in view of the pressures in the first pressure cavity 1, 1 and the second pressure cavity 2, 2 that impact the interlocking segments from the radial inside and from the radial outside.

(93) Typically the pressure in the second pressure cavity 2, 2 is kept significantly below the pressure in the first pressure cavity 1, 1 for this purpose and advantageously the pressure in the second pressure cavity 2, 2 is kept at a level of the securing pressure P4, whereas the lowering pressure in the first pressure cavity 1, 1 is much higher.

(94) After the piston rods 22, 22 have reached the completely retracted position thus their end pieced 6, 6 contact the base of the enveloping cylinder 21, 21 the pressure in both pressure cavities 1, 1 and 2, 2 can be lowered to 0 and thus also the at least one pressure generator supplying the operating cylinder unit 50 can be turned off.

(95) FIGS. 7a, b illustrate a side view and a top view of a lifting device 60 where the operating cylinder unit 50 is the load lifting element standing upright with a piston 22 that is extendable in the upward direction from a cylinder 21 wherein the load lifting element is installed in a base frame 61.

(96) The base frame 61 essentially includes 3 attachment lobes that are essentially distributed over a circumference of the cylinder 21 and arranged in an upper portion of the cylinder 21 wherein a support leg is respective attachable at the attachment lobes with a downward outward slanted slope, wherein only one support leg is drawn in FIG. 7a for reasons of clarity.

(97) Each support leg 62a, b, c contacts the ground with a lower end with an elevation adjustable support base while the centrally arranged operating cylinder unit terminates at a distance above ground.

(98) Between the lower end of the operating cylinder unit 50 and the lower end portion of each support leg 62a, b, c, an additional horizontal strut 63a or b or c can be arranged for stiffening.

(99) The first display device 40 is bolted down at a lower end of the operating cylinder unit 50, thus at the cylinder base and thus well protected by the support legs 62 a, b, c protruding far outward in this elevation range and optionally one of the horizontal struts 63a-c extending thereunder.

(100) As evident already from the top view of FIG. 7b of the cut display device 40 and even better from the detail enlargements according to FIGS. 8a, b the display device 40 includes a sensor cylinder 42b as a sensor element 42 wherein a sensor piston 42a is displace able in the sensor cylinder 42b depending in which of the two operating cavities 43a, b of the sensor cylinder 42b the higher pressure is provided.

(101) As evident from FIG. 8,b the sensor cylinder 42b whose axial direction 42 extends horizontally in this case which however is not mandatory for the invention is only closed at one end by a closure plug that is threaded in sealed tight so that the sensor piston 42a can be replaced after removing the closure plug.

(102) At another axial end the sensor cylinder 42b has a pass through opening that is arranged concentric with the axial direction 42 of the inserted sensor piston 42a with at least one seal in the inner circumference.

(103) The sensor piston 42a includes a one piece piston protrusion 42a1 which extends in the axial direction 42 and which is long enough so that it protrudes through the pass through opening and even out of the housing 45 of the display device 40 so that the end of the piston protrusion 42a1 is visible for the user and shows a correct interlocking or at least a correct pressure loading of the safety elements 4a.

(104) Thus, the sensor piston 42a that is supported tight in the inner circumference of the sensor cylinder 42b contacts the upper end stop in FIG. 8b which occurs when the lower operating cavity 43b is loaded with a higher pressure from the second pressure cavity 2, than in the pressure provided in the first operating cavity 43a from the first pressure cavity 1.

(105) However, when the pressure in the upper operating cavity 43a in the drawing is greater the sensor piston 42a assumes the other end position according to FIG. 8a in that it contacts with its lower end in the drawing figures the closure plug closing the inner cavity of the sensor cylinder 42b.

(106) The required connection of the upper operating cavity 43a in FIGS. 8a, b with the first pressure cavity 1 and of the lower operating cavity 43b with the second pressure cavity 2 are not illustrated in the drawing figures.

(107) FIGS. 8a, b furthermore illustrate the position sensor 44a for the secured position that is arranged in the sensor cylinder 42b proximal to the upper end stop in the drawing figures wherein the position sensor puts out an electrical signal when the sensor piston 42a is at this stop and there after a LED 64 is illuminated by a control, which LED is arranged further upward at the outer circumference of the operating cylinder unit 50 and which is advantageously provided in the same color in which the free end of the piston protrusion 42a1 is provided, advantageously green.

(108) FIGS. 7a, b furthermore illustrate a second display device 40 configured as a manometer 65 which can be provided instead of or in addition to the first display device described supra.

(109) The manometer 65 is in this case provided at an outside of the cylinder 40, advantageously in its upper portion, thus approximately at eye level of an operator standing next to the lifting device.

(110) The manometer 65 indicates the pressure in the first pressure device 1, 1 which would load the safety elements in a direction of an unlocked deactivated position. When this manometer 65 shows a pressure of zero or almost zero, in particular under 0.5 bar this assures that the safety elements are not pressure loaded towards the unlocking direction.

REFERENCE NUMERALS AND DESIGNATIONS

(111) 1, 1 first pressure cavity 1a, 1a first pressure cavity connection 2, 2 second pressure cavity 2a, 2a second pressure cavity connection 3, 3* face 4 position safety 4a safety element, interlocking protrusion, interlocking segment 4a3 support protrusion 4a1, 4b1 front flank 4a2, 4b2 rear flank 4b safety element, interlocking recess 5, 5 piston rod seal unit 6, 6 piston end piece 6* cylinder end piece 6a rear end 6b front end 6c inner cavity 7 receiving ring groove, receiving groove 8 compression spring 9 axial distance 10 axial direction 10a extension direction 10 longitudinal center 11 radial direction, transversal direction 12 circumferential direction 13 support recess 14 supply cavity 15 connection cavity 19 distance 21, 21 cylinder 21a inner circumferential surface 21b cylinder inner space 21c cylinder base 21d center element 22, 22 piston rod 22a circumferential surface, outer circumference piston seal surface 23 throttle 24 throttle 28 pressure relief valve 29 seal sleeve 30 pass through bore hole 31 outer supply tube 32 inner supply tube 40 display device 41 display element 42 sensor element 42a sensor piston 42a1 piston protrusion 42b sensor cylinder 43a, b operating cavity 44a position sensor 45 housing 46 valve block 50 hydraulic cylinder unit, operating cylinder unit 50.1, 50.2 telescoping stage 51 attachment device 51a, b plate 52 pass through bore hole 60 lifting device, tripod 61 base frame 62a-c support leg 63a-c horizontal strut 64 illuminant LED 65 manometer 100 operating cylinder device L, L extension length