Hydraulic axle

Abstract

A hydraulic axle includes a reversible hydraulic pump. The hydraulic axle has a multi-surface cylinder with two retraction surfaces and two deployment surfaces. A first deployment surface and a first retraction surface are configured to interconnect with each other and separate from other surface during a rapid-traverse stroke. A pressure medium is configured to act on the second deployment surface to enable deployment.

Claims

1. A hydraulic axle, comprising: a reversible hydraulic machine; a multi-surface cylinder that includes a piston which has: a first and second retraction surfaces; and a first and second deployment surfaces; a hydraulic circuit that includes control valves configured to actuate the piston during a rapid-traverse stroke and during a power stroke, the control valves including: a first control valve configured to connect the second deployment surface to a first pressure side of the reversible hydraulic machine, a second control valve configured to connect the second retraction surface to a second pressure side of the reversible hydraulic machine, a third control valve configured to connect the first retraction surface to the second pressure side of the reversible hydraulic machine, and a fourth control valve configured to connect the first deployment surface to the first pressure side of the reversible hydraulic machine, the first control valve arranged fluidically in series with the fourth control valve to enable the fourth control valve to connect the first deployment surface to the first pressure side of the reversible hydraulic machine; and a hydraulic accumulator connected to each of the first and second pressure sides of the reversible hydraulic machine, wherein: during the rapid-traverse stroke, the first deployment surface and the first retraction surface are configured to interconnect in a substantially unpressurized fashion via the hydraulic circuit; and during a rapid-traverse deployment stroke, a pressure medium is configured to act on the second deployment surface.

2. The hydraulic axle according to claim 1, wherein during a rapid-traverse retraction stroke, the pressure medium is configured to act on the second retraction surface and the first deployment surface and first retraction surface are configured to interconnect in a substantially unpressurized fashion via the hydraulic circuit.

3. The hydraulic axle according to claim 1, wherein during a power deployment stroke, the first and second deployment surfaces are configured to interconnect, and the first and second retraction surfaces are configured to interconnect.

4. The hydraulic axle according to claim 3, wherein, during the power deployment stroke, the reversible hydraulic machine is configured to connect the interconnected first and second retraction surfaces to the interconnected first and second deployment surfaces.

5. The hydraulic axle according to claim 3, wherein during a decompression after the power deployment stroke, the first and second deployment surfaces are connected to the hydraulic accumulator, and the first and second retracting surfaces are isolated from the reversible hydraulic machine.

6. The hydraulic axle according to claim 1, wherein, during a power retraction stroke, the first and second deployment surfaces are configured to interconnect, and the first and second retraction surfaces are configured to interconnect.

7. The hydraulic axle according to claim 6, wherein, during the power retraction stroke, the reversible hydraulic machine is configured to connect the interconnected first and second retraction surfaces to the interconnected first and second deployment surfaces.

8. The hydraulic axle according to claim 6, wherein during a decompression after the power retraction stroke, the first and second retraction surfaces are connected to the hydraulic accumulator, and the first and second deployment surfaces are isolated from the reversible hydraulic machine.

9. The hydraulic axle according to claim 1, wherein at least one of: the first deployment surface and the first retraction surface are of a substantially equal size; and the second deployment surface and the second retraction surface are of a substantially equal size.

10. The hydraulic axle according to claim 1, further comprising a connecting valve configured to interconnect the first retraction surface and the first deployment surface.

11. The hydraulic axle according to claim 1, wherein at least one of: the second deployment surface is smaller than the first deployment surface; and the second retraction surface is smaller than the first retraction surface.

12. The hydraulic axle according to claim 1, further comprising switching valves arranged in a common valve block together with the reversible hydraulic machine and the hydraulic accumulator, wherein the multi-surface cylinder is configured to connect with the valve block.

13. The hydraulic axle according to claim 1, further comprising a first switching valve configured to connect the first pressure side of the reversible hydraulic machine to the hydraulic accumulator, and a second switching valve configured to connect the second pressure side of the reversible hydraulic machine to the hydraulic accumulator.

14. The hydraulic axle according to claim 13, wherein: during a power deployment stroke, the first and second deployment surfaces are configured to interconnect, and the first and second retraction surfaces are configured to interconnect, and during a decompression after the power deployment stroke, the second switching valve is in an open position so to connect the first and second deployment surfaces to the hydraulic accumulator.

15. The hydraulic axle according to claim 13, wherein: during a power retraction stroke, the first and second deployment surfaces are configured to interconnect, and the first and second retraction surfaces are configured to interconnect, and during a decompression after the power retraction stroke, the first switching valve is in an open position so as to connect the first and second retraction surfaces to the hydraulic accumulator.

16. The hydraulic axle according to claim 13, further comprising a connecting valve configured to interconnect the first retraction surface and the first deployment surface, wherein, during a pressure build-up for preloading the piston, the first control valve is in a closed position, the second, third, and fourth control valves are each in an open position, the connecting valve is in an open position, and the first and second switching valves are each in a closed position such that the first and second deployment surfaces and the first and second retraction surfaces are connected to the accumulator.

17. The hydraulic axle according to claim 1, wherein the second control valve is not arranged fluidically in series with the third control valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred embodiment of the disclosure will be explained in more detail below on the basis of a drawing.

(2) The FIGURE shows the hydraulic axle according to the disclosure in a hydraulic circuit diagram.

DETAILED DESCRIPTION

(3) The single FIGURE illustrates a hydraulic axle 1. This has a multi-surface cylinder 2 (five-surface cylinder) which can be controlled by means of a hydraulic circuit 4. For the supply of pressure medium, a reversible hydraulic pump 6 is provided which can be driven, with variable rotational speed, in two directions of rotation by a drive unit 8. The circuit 4 with the hydraulic pump 6 is arranged in a valve block 10 to which the drive unit 8 and the multi-surface cylinder 2 are connected. From the multi-surface cylinder 2, four pressure ports A, B, C and E are provided on the valve block 10. A first deployment surface A1 of a piston 12 of the multi-surface cylinder 2 is connected to the pressure port A. A second retraction surface A2 of the piston 12 is fluidically connected to the pressure port B. A first retraction surface A3 of the piston 12 is in turn connected to the pressure port C. A further, second deployment surface A5 of the piston 12 is connected to the pressure port E. Furthermore, a surface A4 which acts in the deployment direction is connected to a pressure port D, which in turn is connected to the atmosphere, whereby the surface A4 is relieved of pressure. The first, outer annular retraction surface A3 is of equal size to the first annular deployment surface A1. The circular second deployment surface A5 and the annular second, inner retraction surface A2 are likewise of equal size. The small second deployment surface A5 is connected by means of a first switching valve 14 (control valve) to a first pressure side P1 of the hydraulic pump 6. The second retraction surface A2 is connected by means of a second switching valve 16 (control valve) to a second pressure side P2 of the hydraulic pump 6. Fluidically in parallel with respect to the second switching valve 16, a third switching valve 18 (control valve) is connected to the second pressure side P2 of the hydraulic pump 6, which third switching valve can connect the first retraction surface A3 to the second pressure side P2. A fourth switching valve 20 (control valve) is arranged fluidically in series with respect to the first switching valve 14, wherein the first switching valve 14 is arranged between the fourth switching valve 20 and the hydraulic pump 6. Said fourth switching valve can connect the first deployment surface A1 to the second deployment surface A5 and, when the first switching valve 14 is open, can connect the first deployment surface A1 to the first pressure side P1. The connection to the second deployment surface A5 is provided fluidically between the first switching valve 14 and the fourth switching valve 20.

(4) The first deployment surface A1 and the first retraction surface A3 can be interconnected by means of a connecting valve 22 (switching valve). The connecting valve 22 is connected to the pressure medium flow path between the first deployment surface A1 and the fourth switching valve 20. The connection to the third switching valve 18 branches off from the pressure medium flow path between the first retraction surface A3 and the connecting valve 22.

(5) The circuit 4 furthermore has a hydraulic accumulator 24. Said hydraulic accumulator can be connected by means of a first accumulator valve 26 (switching valve) to the first pressure side P1 and by means of a second accumulator valve 28 (switching valve) to the second pressure side P2 of the hydraulic pump 6. In this case, the first accumulator valve 26 is connected to the pressure medium flow path between the hydraulic pump 6 and the first switching valve 14, and the second accumulator valve 28 is connected to the pressure medium flow path between the hydraulic pump 6 and the second switching valve 16. Furthermore, said accumulator valves are jointly connected to the hydraulic accumulator 24. A respective check valve 30 and 32 is provided fluidically in parallel with respect to the respective accumulator valve 26 and 28. Said check valves open in each case in a pressure medium flow direction away from the hydraulic accumulator 24 toward the first pressure side P1 or second pressure side P2 respectively.

(6) The piston 12 of the multi-surface cylinder 2 is guided slidingly in a cylinder housing 34. Said piston is of hollow cylindrical form, wherein an inner piston rod 38 extends axially in the interior of said piston proceeding from its base 36. A hollow cylindrical guide rod 42, which is fixed with respect to the housing, protrudes by way of its shell into the annular chamber 38 thus formed. The piston rod 38 in turn protrudes into a cylinder chamber 44, which is delimited by the shell, of the guide rod 42. The guide rod 42 has an outer radial collar on its end and the piston 36 has an inner radial collar, wherein these engage behind one another and delimit an annular space 46. Furthermore, the piston 12 has an outer radial collar by means of which it, together with the cylinder housing 34, delimits a further, outer annular space 48. The first deployment surface A1 is thus acted on with pressure medium via the annular chamber 40. The second deployment surface A5 is acted on with pressure medium via the cylinder chamber 44. The second and first retraction surfaces A2, A3 are acted on with pressure medium via the annular chambers 46 and 48 respectively. The pressure-relieved surface A4, together with an inner shell surface of the cylinder housing 34 and an outer shell surface of the guide rod 42, delimits a pressure-relieved annular space 50. In this case, the surface A4 points away from the surfaces A2 and A3.

(7) The mode of operation of the hydraulic axle will be described below.

(8) Rapid-Traverse Deployment Stroke:

(9) In the rapid-traverse deployment stroke, the hydraulic pump 6 delivers pressure medium from its second pressure side P2 to its first pressure side P1. Actuators of the switching valves 14 and 16 are energized and the switching valves 14, 16 are thus open. The actuator of the fourth switching valve 20 is likewise energized, as a result of which said fourth switching valve is closed. Furthermore, the actuator of the connecting valve 22 is energized, and said connecting valve is thus open. The other switching valves 18, 26 and 28 are deenergized, and closed. Owing to the connecting valve 22 being open, the second deployment surface A1 and the first retraction surface A3, which is of equal size, are interconnected and separated from the other piston surfaces. The hydraulic pump 6 now delivers pressure medium from the second retraction surface A2 via the switching valve 16 to the switching valve 14 and onward to the second deployment surface A5, as a result of which the piston 12 is deployed. During said deployment movement, therefore, only the second deployment surface A5 is subjected to pressure, as a result of which only a small number of seals of the multi-surface cylinder 2 are subjected to a high pressure. The piston 2 can thus be deployed in a freely moving manner.

(10) Power Deployment Stroke:

(11) In this case, the hydraulic pump 6 again delivers pressure medium from the second pressure side P2 to the first pressure side P1. Now, both deployment surfaces A1 and A5 are connected to the high-pressure side of the hydraulic pump 6, that is to say to the first pressure side P1. For this purpose, the switching valves 14 and 20 are open and the connecting valve 22 is closed. Furthermore, the first and second retraction surfaces A3, A2 have a pressure medium connection to the low-pressure side of the hydraulic pump 6, that is to say to its second pressure side P2. For this purpose, the switching valves 16 and 18, which are fluidically in parallel, are open. The accumulator valves 26 and 28 are closed. The hydraulic pump 6 now delivers pressure medium from the retraction surfaces A2, A3 via the switching valves 16, 18 to the deployment surfaces A1 and A5 via the switching valves 14 and 20.

(12) Decompression after the Power Deployment Stroke:

(13) In the decompression after the power deployment stroke, the deployment surfaces A1 and A5 are connected to the hydraulic accumulator 24, and the retraction surfaces A2 and A3 are shut off. For the connection of the deployment surfaces A1 and A5 to the hydraulic accumulator 24, the first switching valve 14 and the fourth switching valve 20 are opened. Furthermore, the second accumulator valve 28 is opened. The second switching valve 16, the third switching valve 18 and the connecting valve 22 are closed. The hydraulic pump 6 delivers pressure medium from its first pressure side P1 to its second pressure side P2. Thus, pressure medium is delivered from the first deployment surface A1 and the second deployment surface A5 via the fourth switching valve 20 and the first switching valve 14 to the hydraulic accumulator 24 via the second switching valve 28.

(14) Rapid-Traverse Retraction Stroke:

(15) In the rapid-traverse retraction stroke, the hydraulic pump 6 delivers pressure medium from its first pressure side P1 to its second pressure side P2. The first deployment surface A1 and the first retraction surface A3 are interconnected by means of the connecting valve 22 and are fluidically separated from the other piston surfaces. The first and second switching valves 14 and 16 are open. The third and fourth switching valves 18 and 20 are closed. Furthermore, the accumulator valves 26 and 28 are closed. The hydraulic pump 6 now delivers pressure medium from the second deployment surface A5 via the first switching valve 14 to the second retraction surface A2 via the second switching valve 16.

(16) Power Retraction Stroke:

(17) In this case, the hydraulic pump 6 delivers pressure medium from its first pressure side P1 to its second pressure side P2. In the power retraction stroke, pressure medium is delivered from the deployment surfaces A1 and A5 to the retraction surfaces A2 and A3. For this purpose, all of the switching valves 14 to 20 are open. The accumulator valves 26, 28 and the connecting valve 22 are closed. The hydraulic pump 6 then delivers pressure medium from the deployment surfaces A1 and A5 via the switching valves 14, 20 to the retraction surfaces A2 and A3 via the switching valves 16, 18.

(18) Decompression after the Power Retraction Stroke:

(19) The hydraulic pump 6 delivers pressure medium from its second pressure side P2 to its first pressure side P1. In the decompression, the retraction surfaces A2 and A3 are connected to the hydraulic accumulator 24, whereas the deployment surfaces A1 and A5 are shut off. The second and third switching valves 16 and 18 and the first accumulator valve 26 are open. The first switching valve 14 and the connecting valve 22 are closed. If required, the fourth switching valve 20 may also be closed. The hydraulic pump 6 now delivers pressure medium from the retraction surfaces A2 and A3 via the switching valves 16 and 18 to the hydraulic accumulator 24 via the accumulator valve 26.

(20) Pressure-Holding Phase:

(21) In the pressure-holding phase, all of the switching valves 14 to 20 and the connecting valve 22 are closed in order that pressure medium at the deployment surfaces A1, A5 and at the retraction surfaces A2, A3 cannot escape, and the piston 12 is braced in its position.

(22) Pressure Build-Up Phase for Preloading:

(23) In the pressure build-up phase for preloading, the deployment surfaces A1 and A5 and the retraction surfaces A2 and A3 are connected to the hydraulic accumulator 24. The hydraulic pump 6 delivers pressure medium from the first pressure side P1 to the second pressure side P2. The first switching valve 14 and the accumulator valves 26 and 28 are closed. The switching valves 16, 18 and 20 and the connecting valve 22 are open. The hydraulic pump 6 can now deliver pressure medium from the hydraulic accumulator 24 via the first check valve 30 to the deployment surfaces A1 and A5 and to the retraction surfaces A2 and A3.

(24) The disclosure discloses a hydraulic axle with a reversible hydraulic pump. The axle has a multi-surface cylinder with two retraction surfaces and two deployment surfaces. In a rapid-traverse stroke, a first deployment surface and a first retraction surface can be interconnected and separated from the other surfaces. For deployment, the second deployment surface is acted on with pressure medium.

LIST OF REFERENCE SIGNS

(25) 1 Hydraulic axle 2 Multi-surface cylinder 4 Circuit 6 Hydraulic pump 8 Drive unit 10 Valve block 12 Piston 14 First switching valve 16 Second switching valve 18 Third switching valve 20 Fourth switching valve 22 Connecting valve 24 Hydraulic accumulator 26 First accumulator valve 28 Second accumulator valve 30 First check valve 32 Second check valve 34 Cylinder housing 36 Base 38 Piston rod 40 Annular chamber 42 Guide rod 44 Cylinder chamber 46 Annular space 48 Annular space 50 Annular space A1 First deployment surface A2 Second retraction surface A3 First retraction surface A4 Pressure-relieved surface A5 Second deployment surface P1 First pressure side P2 Second pressure side