CYLINDER UNIT

Abstract

Relates to a cylinder unit includes a rod and a housing, wherein the rod is guided on the housing so as to be displaceable along an adjustment axis, wherein a piston is fixed to the rod, which piston divides the interior space of the housing into a first chamber and a second chamber, wherein the housing has a safety outlet, and wherein the safety outlet is arranged such that the piston closes off the safety outlet in fluid-tight fashion when the rod is in a zero position.

Claims

1.-15. (canceled)

16. A cylinder unit, comprising: a rod; a housing, wherein the rod is guided on the housing so as to be displaceable along an adjustment axis; and a piston is fixed to the rod, the piston dividing the interior space of the housing into a first chamber and a second chamber; wherein the housing as a safety outlet that is arranged and configured such that the piston closes off the safety outlet in a fluid-tight manner when the rod is in a zero position; wherein a first safety port and a first working port are arranged on at least one of the housing and the first port and are open into the first chamber; wherein a second safety port and a second working port are arranged on at least one of the housing and the second port and are open into the second chamber; and wherein two actuating elements block at least one of the safety ports and the working ports.

17. The cylinder unit as claimed in claim 16, wherein the safety outlet includes an aperture in an inner wall of the housing, and wherein the piston has an extent parallel to the adjustment axis which is at least as great as the extent of the safety outlet parallel to the adjustment axis.

18. The cylinder unit as claimed in claim 17, wherein the housing has two ports, wherein the first port opens into the first chamber and the second port opens into the second chamber, and wherein the safety outlet is arranged at least one of above and opposite the ports.

19. The cylinder unit as claimed in claim 18, wherein at least one of an operating fluid and a safety fluid can be introduced into the chambers via the ports.

20. The cylinder unit as claimed in claim 19, wherein the piston has two seal elements, wherein the spacing measured parallel to the adjustment axis of the seal elements to one another is equal to or greater than the extent of the safety outlet parallel to the adjustment axis.

21. The cylinder unit as claimed in claim 20, wherein the rod has a first piston and a second piston which are spaced apart from one another, wherein the first piston separates a first safety chamber and a second safety chamber from one another, wherein the second piston separates a first working chamber and a second working chamber from one another, and wherein the second working chamber and the second safety chamber are separated from one another by a partition of the housing.

22. The cylinder unit as claimed in claim 21, wherein a safety mode of the cylinder unit can be produced by introducing a fluid at equal pressure into the first and the second safety chamber, and wherein the first piston is designed to close off the safety outlet in fluid-tight fashion after a displacement in the direction of the safety outlet.

23. The cylinder unit as claimed in claim 21, having an operating mode where the second piston is displaceable along the adjustment axis by at least one of a fluid of the first working chamber and of the second working chamber, and wherein the first and the second safety chamber are empty of fluid.

24. The cylinder unit as claimed in claim 21, wherein the first and the second safety chamber are configured to be filled with compressed air.

25. The cylinder unit as claimed in claim 24, wherein each actuating element has a restoring element which is preloaded and which acts on the actuating element such that the restoring element is displaced into the position in which the restoring element blocks the working port and opens up the safety port.

26. The cylinder unit as claimed in claim 25, wherein a control force which acts counter to the force of the restoring element can be applied to an actuating element, and wherein, if the control force prevails, the actuating element is configured to be moved into the position in which the actuating element blocks the safety outlet and opens up the working port.

27. The cylinder unit as claimed in claim 25, wherein the safety outlet is configured to be closed off, and wherein the safety outlet is closed off when the actuating elements block the safety ports.

28. The cylinder unit as claimed in claim 27, wherein a blocking unit is provided for securing the rod in the zero position.

29. The cylinder unit as claimed in claim 28, wherein the blocking unit is at least one of fixed to the housing and integrated at least in regions into the housing.

30. The cylinder unit as claimed in claim 16, wherein the housing has two ports, wherein the first port opens into the first chamber and the second port opens into the second chamber, and wherein the safety outlet is arranged at least one of above and opposite the ports.

31. The cylinder unit as claimed in claim 30, wherein at least one of an operating fluid and a safety fluid can be introduced into the chambers via the ports.

32. The cylinder unit as claimed in claim 16, wherein the piston has two seal elements, wherein the spacing measured parallel to the adjustment axis of the seal elements to one another is equal to or greater than the extent of the safety outlet parallel to the adjustment axis.

33. The cylinder unit as claimed in claim 16, wherein the rod has a first piston and a second piston which are spaced apart from one another, wherein the first piston separates a first safety chamber and a second safety chamber from one another, wherein the second piston separates a first working chamber and a second working chamber from one another, and wherein the second working chamber and the second safety chamber are separated from one another by a partition of the housing.

34. The cylinder unit as claimed in claim 33, wherein a safety mode of the cylinder unit can be produced by introducing a fluid at equal pressure into the first and the second safety chamber, and wherein the first piston is designed to close off the safety outlet in fluid-tight fashion after a displacement in the direction of the safety outlet.

35. The cylinder unit as claimed in claim 33, having an operating mode where the second piston is displaceable along the adjustment axis by at least one of a fluid of the first working chamber and of the second working chamber, and wherein the first and the second safety chamber are empty of fluid.

36. The cylinder unit as claimed in claim 33, wherein the first and the second safety chamber are configured to be filled with compressed air.

37. The cylinder unit as claimed in claim 16, wherein each actuating element has a restoring element which is preloaded and which acts on the actuating element such that the restoring element is displaced into the position in which the restoring element blocks the working port and opens up the safety port.

38. The cylinder unit as claimed in claim 37, wherein a control force which acts counter to the force of the restoring element can be applied to an actuating element, and wherein, if the control force prevails, the actuating element is configured to be moved into the position in which the actuating element blocks the safety outlet and opens up the working port.

39. The cylinder unit as claimed in claim 37, wherein the safety outlet is configured to be closed off, and wherein the safety outlet is closed off when the actuating elements block the safety ports.

40. The cylinder unit as claimed in claim 16, wherein a blocking unit is provided for securing the rod in the zero position.

41. The cylinder unit as claimed in claim 40, wherein the blocking unit is at least one of fixed to the housing and integrated at least in regions into the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further advantages and features of the present invention will emerge from the following description with reference to the appended figures. Here, it is self-evident that some of the features shown in the figures may also be used in other embodiments unless this is prohibited owing to technical circumstances or has been explicitly ruled out. In the figures:

[0020] FIG. 1 shows a partially sectional view of a first preferred embodiment of the cylinder unit according to the invention;

[0021] FIG. 2 shows a sectional view of a further preferred embodiment of the cylinder unit according to the invention; and

[0022] FIG. 3 shows a further preferred embodiment of the cylinder unit according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The preferred embodiment of the cylinder unit shown in FIG. 1 has a housing 4, a rod 2, and a piston 24 fixed to the rod 2. Here, the rod 2 is displaceable relative to the housing 4 along the adjustment axis S, and, at the face sides of the housing, is secured in each case against displacement transversely with respect to the adjustment axis S. Furthermore, the housing has a first port 42 and a second port 43, wherein the first port 42 opens into the first chamber 8 and the second port 43 opens into the second chamber 9. The piston 24 separates the first chamber 8 from the second chamber 9. It is furthermore preferable for a first safety port 42a and a first working port 42b to be provided on the first port 42. A second safety port 43a and a second working port 43b preferably open in at the second port 43. In the region in which the safety ports 42a, 43a and the working ports 42b, 43b open in, there is provided in each case one actuating element 12 which alternately blocks either the safety port 42a, 43a or the working port 42b, 43b and opens up the respective other port. In the embodiment illustrated, the actuating element 12 is in each case arranged such that the safety port 42a, 43a is closed off and the working port 42b, 43b is open. The state of the cylinder unit illustrated in the figure is thus the normal operating mode of the cylinder unit, in which the rod 2 can be displaced along the adjustment axis by means of an inflow and outflow of fluid into and out of the first chamber 8 and the second chamber 9. In this state, the safety outlet 44 is preferably closed off. In other words, in this state, the cylinder unit functions as a normal hydraulic or pneumatic cylinder, by means of which a steering movement at the wheels of the utility vehicle can be realized. Dashed lines in FIG. 1 illustrate the state of the actuating elements 12 in which the latter open up the safety port 42a, 43a and close off the working port 42b, 43b. In this position, a safety fluid can flow into the first chamber 8 and the second chamber 9, wherein the piston 24 is displaced along the adjustment axis S by the fluid flowing into the two chambers 8, 9 until said piston is situated exactly over the safety outlet 44 and a flow of the safety fluid out of the cylinder unit via the safety outlet 44 is prevented. Proceeding from the state shown in FIG. 1, the piston would thus be displaced to the right until it is situated exactly over the safety outlet 44 and its two seals 10 seal off the right-hand side and the left-hand side of the safety outlet 44. On the actuating elements 12, there is particularly preferably provided a restoring means 13 which is preloaded such that it seeks to displace the actuating elements 12 in the direction of the position illustrated by dashed lines. An arrow pointing counter to the action of the restoring means 13 is used to indicate a control force which is generated by the system or by a control unit of the utility vehicle during normal operation, which is at least as great as the restoring force of the restoring element 13, and which displaces the actuating element 12 in each case into the position in which the safety port 42a, 43a is closed off and the working ports 42b and 43b are in each case open.

[0024] FIG. 2 shows an alternatively preferred embodiment of the cylinder unit according to the invention, wherein the working circuit and the safety circuit of the cylinder unit are preferably provided so as to be separated from one another, particularly preferably spatially separated from one another. Here, the housing 4 has the working region on the left-hand side, which working region is provided so as to be separated from the safety region of the housing 4 by a partition 46. In the safety region, it is preferable for a first safety chamber 8a and a second safety chamber 9a to be provided so as to be separated from one another by a first piston 24a. The first piston 24a has two seals 10, the spacing of which to one another is greater than the extent of the safety outlet 44 along or parallel to the adjustment axis S. Furthermore, it is preferable for a first safety port 42a to open into the first safety chamber 8a and for a second safety port 43a to open into the second safety chamber 9a. Provided on the left adjacent to the partition 46, and thus so as to be preferably entirely separated from the safety region, is a working region in which a first working chamber 8b and a second working chamber 9b are separated from one another by a second piston 24b. A first working port 42b opens into the first working chamber 8b and a second working port 43b opens into the second working chamber 9b. During normal operation, the rod 2 is preferably achieved along the adjustment axis S by means of the second piston 24b by means of an inflow and outflow of fluid into and out of the first working chamber 8b and the second working chamber 9b. If the hydraulic or pneumatic system of the utility vehicle fails and there is no longer sufficient pressure available for the pressurization of the first working chamber 8b and of the second working chamber 9b, a safety fluid is preferably introduced at equal pressure into the first safety chamber 42a and the second safety chamber 43a. Here, in the state shown in FIG. 2, a higher pressure builds up on the left-hand side of the first piston 24a in the second safety chamber 9a than in the first safety chamber 8a. For as long as the safety outlet 44 is not yet closed by the first piston 24a, it is thus possible for the fluid flowing into the first safety chamber 8a to flow out through the safety outlet 44, whereas the safety fluid flowing into the second safety chamber 9a generates a build-up of pressure therein. The pressure in the second safety chamber 9a thus exceeds the pressure in the first safety chamber 8a, and the first piston 24a performs a movement to the right. As soon as the rod 2 together with the first piston 24a is situated in the zero position, in which the first piston 24a is arranged exactly at the level of the safety outlet 44, safety fluid can no longer flow out through the safety outlet 44. As a result, the same pressure builds up in the first safety chamber 8a and in the second safety chamber 9a, whereby pneumatic or hydraulic blocking of the first piston 24 is generated. In this way, the rod 2 is hydraulically or pneumatically secured against displacement along or parallel to the pivot axis S. A damper 11 is preferably connected to the safety ports 42a, 43a, which damper is for example based on the principle of fluid friction damping. The damper 11 is preferably connected between the lines leading to the safety ports 42a, 43a, and preferably comprises an orifice. Vibrations of the rod 2 relative to the housing 4 can thus be dampened both during normal operation of the cylinder unit and during safety operation. The damper 11 is preferably equipped with a closure mechanism, preferably a shut-off valve, in order that the action of the hydraulic steering blocking is not disrupted after the closure of the safety outlet 44. A damper 11 may preferably also be used in the embodiments shown in FIGS. 1 and 3.

[0025] FIG. 3 shows an embodiment of the cylinder unit in which, in addition to the embodiment of FIG. 2, a blocking unit 6 is also provided on the housing 4, preferably in the region of the partition 46 from FIG. 2. Here, it is shown that the blocking unit 6, in a second position, prevents a displacement of the rod 2 along the adjustment axis S by means of a blocking element 62 which engages into an engagement section 22 on the rod 2. Here, said securing action is realized in addition or alternatively to blocking of the rod by means of the first piston 24a and the fluid situated in the first and the second safety chamber 8a, 9a. Furthermore, the blocking support 64 is preferably formed for the most part integrally with the housing 4. Here, only the cover 67 is screwed on after the insertion of the blocking element 62 and the restoring means 66, which simplifies the assembly process and ensures a high level of stability of the interface between housing 4 and blocking unit 6. It is self-evident that both the unipartite design and the multi-part design of said interface may be used in all other variants of the invention that are not shown here. In the second position of the blocking unit 6, the blocking element 62 is in engagement with the engagement section 22 of the rod 2. In the second state of the blocking unit 6 as shown in FIG. 3, a displacement movement of the rod 2 along the adjustment axis S relative to the housing 4 and relative to the blocking unit 6 is no longer possible. To place the blocking unit 6 into a first state again in which the blocking element 62 is not in engagement with the rod 2, the pressure of a holding means must be increased, such that the force of the holding means exceeds the restoring force of the restoring means 66, and the blocking element 62 can ultimately be disengaged from the rod 2 again.

LIST OF REFERENCE DESIGNATIONS

[0026] 2Rod [0027] 24Piston [0028] 24aFirst piston [0029] 24bSecond piston [0030] 4Housing [0031] 42First port [0032] 42aFirst safety port [0033] 42bFirst working port [0034] 43Second port [0035] 43aSecond safety port [0036] 43b?Second working port [0037] 44Safety outlet [0038] 6Blocking unit [0039] 8First chamber [0040] 8aFirst safety chamber [0041] 8bFirst working chamber [0042] 9Second chamber [0043] 9aSecond safety chamber [0044] 9bSecond working chamber [0045] 10Seal element [0046] 11Damper [0047] 12Actuating element [0048] 13Restoring element [0049] SAdjustment axis