Hydraulic Cylinder Assembly and Method for Operating a Hydraulic Cylinder Assembly

Abstract

A hydraulic cylinder assembly includes a hydraulic cylinder, a motor for driving an adjustable pump, the pump, and a pivot angle control system for the pump. The pivot angle control system has at least one adjustment piston for adjusting the pump and an electrically controllable valve for controlling the adjustment piston. At least one conveying direction of the pump and thus a movement of the hydraulic cylinder is controllable via the pivot angle control system. The hydraulic cylinder assembly further includes an electrical control unit for operating at least the motor and the valve and an uninterruptible power supply, configured such that, in the event of a failure of a power supply for the control unit, at least the control unit can be supplied with electrical power from the uninterruptible power supply.

Claims

1. A hydraulic cylinder assembly comprising: a hydraulic cylinder; an adjustable pump; a motor configured to drive the adjustable pump; a pivot angle control system configured to adjust at least one conveying direction of the adjustable pump and thus a movement of the hydraulic cylinder, the pivot angle control system comprising: at least one adjustment piston configured to adjust the adjustable pump; and an electrically controllable valve configured to control the at least one adjustment piston; an electrical control unit configured to operate at least the motor and the valve; and an uninterruptible power supply configured to, when a power supply for the control unit fails, supply at least the control unit with electrical power.

2. The hydraulic cylinder assembly according to claim 1, wherein the hydraulic cylinder assembly is configured such that, when the power supply for the control unit fails, at least the valve is controllable via the power supplied by the uninterruptible power supply in such a way that a pivot angle of the adjustable pump is adjusted to zero percent via the adjustment piston.

3. The hydraulic cylinder assembly according to claim 1, wherein the hydraulic cylinder assembly is configured such that, when the power supply for the control unit fails, the motor is be decelerated to zero RPM via the power supplied by the uninterruptible power supply.

4. The hydraulic cylinder assembly according to claim 1, wherein the uninterruptible power supply comprises a capacitor or a DC link connected to the power supply for the control unit, and the capacitor or the DC link provides the power for supplying at least the control unit when the power supply for the control unit fails.

5. A method for operating a hydraulic cylinder assembly, the hydraulic cylinder assembly including (i) a hydraulic cylinder, (ii) an adjustable pump, (iii) a motor configured to drive the adjustable pump, (iv) a pivot angle control system configured to adjust at least one conveying direction of the adjustable pump and thus a movement of the hydraulic cylinder, the pivot angle control system having at least one adjustment piston configured to adjust the adjustable pump and an electrically controllable valve configured to control the at least one adjustment piston, (v) an electrical control unit configured to operate at least the motor and the valve, and (vi) an uninterruptible power supply, the method comprising: when a power supply for the control unit fails: supplying at least the control unit with electrical power from the uninterruptible power supply; and decelerating the motor to zero rpm using energy supplied by the uninterruptible power supply, or actuating the valve using energy supplied by the uninterruptible power supply, so that a pivot angle of the adjustable pump is adjusted to zero percent via the adjustment piston.

6. The method according to claim 5, wherein the power supplied by the uninterruptible power supply is consumed entirely during the decelerating of the motor or the actuating of the valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The disclosure as well as the technical environment will now be explained in greater detail with reference to figures, without these statements limiting the disclosure itself. To the extent that it is not explicitly excluded below, partial aspects or individual features shown in the figures can also be combined with one another and/or with the features of the claims or the preceding description. To the extent that components in different figures are provided with the same reference numeral, their descriptions apply mutatis mutandis to all of these components, unless otherwise explicitly stated. The figures schematically show:

[0051] FIG. 1 a first design variant of a hydraulic cylinder assembly according to the prior art,

[0052] FIG. 2 a second design variant of a hydraulic cylinder assembly according to the prior art,

[0053] FIG. 3 a third design variant of a hydraulic cylinder assembly according to the prior art,

[0054] FIG. 4 a fourth design variant of a hydraulic cylinder assembly according to the prior art,

[0055] FIG. 5 a first design variant of a hydraulic cylinder assembly; and

[0056] FIG. 6 a second design variant of a hydraulic cylinder assembly.

DETAILED DESCRIPTION

[0057] FIG. 1 shows a first design variant of a hydraulic cylinder assembly 1 according to the prior art.

[0058] The hydraulic cylinder assembly 1 comprises a hydraulic cylinder 2, an adjustable pump 4 driven by a motor 3, and two shut-off valves 14. Thus, after a shutdown of the hydraulic cylinder assembly 1, a (residual) movement of the piston of the hydraulic cylinder 2 can be prevented. By means of the shut-off valves 14, a hydraulic connection between the two chambers of the hydraulic cylinder 2 and the pump 4 is interrupted. The motor 3 provided in order to drive the pump 4 is shifted free of torque.

[0059] FIG. 2 shows a second design variant of a hydraulic cylinder assembly 1 according to the prior art. Reference is made to the statements regarding FIG. 1.

[0060] By contrast to the first design variant, no shut-off valves 14 are provided here, so that the piston of the hydraulic cylinder 2 is moved further as the medium is conveyed by the pump 4. A simple triggering of an STO on the motor 3 will only result in a stoppage of the pump 4 when the kinetic energy of the motor 3 and the pump 4 is dissipated (provided no external hydraulic forces are acting on the pump 4). The pump 4 conveys according to its direction of rotation and, if applicable, its pivot angle 11.

[0061] FIG. 3 shows a third design variant of a hydraulic cylinder assembly 1 according to the prior art. Reference is made to the statements regarding FIG. 2.

[0062] This hydraulic cylinder assembly 1 comprises a pivot angle control system 5. The hydraulic cylinder assembly 1 comprises a hydraulic cylinder 1 (with a piston), a motor 3 for driving an adjustable pump 4, the pump 4, and a pivot angle control system 5 for the pump 4, wherein the pivot angle control system 5 comprises at least one adjustment piston 6 for pump 4 displacement and an electrically controllable valve 7 for controlling the adjustment piston 6. At least one direction of conveyance or pivot angle 11 of the pump 4 and thus a movement of the hydraulic cylinder 2 or the piston is controllable via the pivot angle control system 5. The pump 4 is adjustable through the pivot control system 5 between 100% (maximum discharge rate of the pump 4 in a first direction), 0% (no delivery of a medium through the pump 4), and +100% (maximum discharge rate of the pump 4 in a second direction).

[0063] If the (pivot angle control) valve 7 is switched to its de-energized default position

[0064] analogously to the STO of the motor 3, then the resulting pivot angle 11 of the pump 4, and thus whether and in which direction the pump 4 conveys, depends on the default position of the valve, the valve pressure supply, and the presence of springs in the pivot cradle.

[0065] In a so-called A4 HS5 pump with connected control pressure (pressure port 12) and de-energized proportional valve or HS5 control valve (as the valve 7, i.e. a 4/4 way valve), for example, the minimum displacement of the pump 4 is the default position shown here. One chamber of the adjustment piston 6 is connected to the pressure port 12 and the other chamber of the adjustment piston 6 is connected to the return flow 13. This default position is also achieved when the HS5 control valve 7 is de-energized due to a fault (e.g. cable break, etc.). By contrast to an open circuit in which the pump 4 pivots to a minimum limit stop (zero % discharge), the pump 4 pivots beyond the zero position in the closed circuit to 100% discharge (direction reversal). In this case, the hydraulic cylinder 2 connected to the pump 4 accelerates in a maximum direction of movement. By implementing a zero-pivot function (see FIG. 4) into the known HS5 (E) control system, this behavior can be prevented.

[0066] In order to enable the pump 4 to be pivoted to a pivoting angle 11 of zero % with a de-energized pivot angle control valve 7 in case of, for example, pumps 4 with this kind of unfavorable default position of the pivot angle control valve (valve 7), an additional (second) valve 16 and an additional (second) piston 17 or cylinder can be provided (see FIG. 4).

[0067] FIG. 4 shows a fourth design variant of a hydraulic cylinder assembly 1 according to the prior art. Reference is made to the statements regarding FIG. 3.

[0068] By contrast to the third design variant, a second valve 16 and a second piston 17 are provided in this hydraulic cylinder assembly 1.

[0069] In normal operation of the hydraulic cylinder assembly 1, the electrically actuated 4/4-way valve 7 controls the pressure ratios in the adjustment piston 6 as the (first) valve and thus pivots the pump 4. The first valve 7 is thus loaded with current and unloads the second piston 17, which is thus ineffective/powerless. In the event of a fault of the (first) valve 7, the valve moves to the shown default position in which the one (first) chamber of the adjustment piston 6 is connected to the return flow 13 and is thus unloaded. The other (second) chamber of the adjustment piston 6 is connected to the pressure port 12 and thus to the adjustment pressure. This causes the adjustment piston 6 to be moved towards the first chamber. In order to prevent the end position of the adjustment piston 6 (in which a maximum conveying quantity of the pump 4 is set), the second valve 16 is deactivated and connects the second piston 17 or cylinder with the pressure port 12. As a result, the second piston 17 extends to an adjustable limit stop (which corresponds to the center position, i.e. the zero % position of the pump 4). The effective surface of the second piston 17 is larger than the effective surface of the adjustment piston 6, so that it is ensured that the end position of the second piston 17 or cylinder is achieved, which in turn corresponds to the center position, i.e. the zero % position of the pump 4.

[0070] However, the second piston 17 and second valve 16 are required in order to implement this hydraulic cylinder assembly 1.

[0071] FIG. 5 shows a first design variant of a hydraulic cylinder assembly 1. Reference is made to the statements regarding FIGS. 1-4.

[0072] The hydraulic cylinder assembly 1 comprises a hydraulic cylinder 2, a motor 3 for driving an adjustable pump 4, the pump 4, and a pivot angle control system 5 for the pump 4, wherein the pivot angle control system 5 comprises at least one adjustment piston 6 for pump 4 displacement and an electrically controllable valve 7 for controlling the adjustment piston 6. At least one direction of conveyance or pivot angle 11 of the pump 4 (between 100% and +100% conveying quantity) and thus a movement of the hydraulic cylinder 2 is controllable via the pivot angle control system 5. The hydraulic cylinder assembly 1 comprises an electrical control unit 8 for operating at least the motor 3 and the valve 7.

[0073] The hydraulic cylinder assembly 1 further comprises an uninterruptible power supply 9, such that in the event of a failure of a power supply 10 for the control unit 8, e.g. by actuating the emergency stop switch 15, at least the control unit 8 can be supplied with electrical power from the uninterruptible power supply 9.

[0074] In the event of a failure of the power supply 10 for the control unit 8, the valve 7 can be controlled via the power supplied by the uninterruptible power supply 9 so that a pivot angle 11 of the pump 4 can be adjusted to zero % via the adjustment piston 6.

[0075] In the event of a failure of the power supply 10 for the control unit 8, the motor 3 can also be decelerated to zero rpm via the energy supplied by the uninterruptible power supply 9 through a decelerating resistor 22.

[0076] In particular, the uninterruptible power supply 9 comprises a capacitor 23 or a DC link

[0077] connected to the power supply 10, wherein the capacitor 23 or the DC link provides the power for supplying at least the control unit 8 in the event of a failure of the power supply 10.

[0078] The uninterruptible power supply 9 can thus ensure that the hydraulic cylinder 1 reaches a stop (the pump 4 no longer conveys or is in the zero % position and the motor 3 no longer drives the pump 4).

[0079] The method for operating the hydraulic cylinder assembly 1 comprises, in the event of failure of the power supply 10 according to step a), supplying electrical power to at least the control unit 8 from the uninterruptible power supply 9. According to step b), the motor 3 is decelerated to zero rpm using energy supplied by the uninterruptible power supply 9, and the valve 7 is actuated using energy supplied by the uninterruptible power supply, so that a pivot angle 11 of the pump 4 is adjusted to zero % via the adjustment piston 6.

[0080] Steps a) and b) are carried out together, meaning that only the electrical energy from the uninterruptible power supply 9 is used in order to slow down the motor 3 and actuate the valve 7 and thus the adjustment piston 6.

[0081] Without the actuation of the valve 7, the valve 7 would otherwise move to the shown default position, in which the adjustment piston 6 is transferred to one of the end positions, so that the pump 4 would then be adjusted to 100% or +100% pivot angle 11 and the hydraulic cylinder 1 would continue to move.

[0082] As part of step b), the energy supplied by the uninterruptible power supply 9 is completely consumed. The hydraulic cylinder assembly 1 is therefore de-energized after step b), i.e. there is no more electrical energy in the hydraulic cylinder assembly 1 (i.e. in the control unit 8, the uninterruptible power supply 9, or other components).

[0083] FIG. 6 shows a second design variant of a hydraulic cylinder assembly 1. Reference is made to the explanations regarding FIG. 5.

[0084] By contrast to the first design variant shown in FIG. 5, FIG. 6 shows a hydraulic cylinder assembly 1 having a differently designed uninterruptible power supply 9. The uninterruptible power supply 9 is designed as an additional 24V power supply 19, which is supplied from the DC link 18. Both power supplies 19 (power supply 19 and power supply of the DC link 18) lead to an additional redundancy module 20. As long as the DC link 18 is still charged, 24V is also present.

[0085] In addition, in FIG. 6, a PLC 21 is still powered via the uninterruptible power supply 9. The control of the (pivot angle control) valve 7 is housed in an external electronics 24, which is also powered via the uninterruptible power supply 9.