Electrohydraulic System with a Hydraulic Spindle and at least One Closed Hydraulic Circuit

Abstract

An electrohydraulic system includes a hydraulic load and at least one closed hydraulic circuit. The hydraulic circuit includes at least one control mechanism, a hydraulic machine, and a closed hydraulic reservoir. The closed hydraulic circuit is filled with degassed hydraulic fluid. A method, in one embodiment, includes filling the electrohydraulic system with degassed hydraulic fluid. In one embodiment, equipment is provided for filling the electrohydraulic system with the degassed hydraulic fluid

Claims

1. An electrohydraulic system, comprising: a hydraulic consumer; and at least one closed hydraulic circuit that includes at least one control mechanism, a hydraulic machine, and a closed hydraulic reservoir, wherein the closed hydraulic circuit is filled with degassed hydraulic fluid.

2. The electrohydraulic system according to claim 1, wherein a residual gas content of the degassed hydraulic fluid is 10% at most.

3. The electrohydraulic system according to claim 1, wherein the hydraulic consumer comprises a dynamically actuable axle and a residual gas content of the degassed hydraulic fluid falls within the range of 7% to 9%.

4. The electrohydraulic system according to claim 1, wherein the hydraulic consumer comprises a statically actuable axle and a residual gas content of the degassed hydraulic fluid falls within the range of 2% to 5%.

5. The electrohydraulic system according to claim 1, wherein degassed oil is used as the degassed hydraulic fluid.

6. A method for setting up an electrohydraulic system that includes a hydraulic consumer and a closed hydraulic circuit, the hydraulic circuit including at least one control mechanism, a hydraulic machine, and a closed-off hydraulic reservoir, the method comprising: evacuating the hydraulic circuit; and filling the closed hydraulic circuit with degassed hydraulic fluid.

7. The method according to claim 6, wherein filling the closed hydraulic circuit includes introducing the degassed hydraulic fluid into the hydraulic circuit by excess pressure.

8. An apparatus for setting up an electrohydraulic system that includes a hydraulic consumer and a closed hydraulic circuit, the hydraulic circuit including at least one control mechanism, a hydraulic machine, and a closed-off hydraulic reservoir, the apparatus comprising: a fluid inlet on the hydraulic reservoir; a vacuumizing arrangement configured to act on the hydraulic circuit; and a device configured to provide degassed hydraulic fluid, the device including at least one vacuumizing arrangement configured to act on a separate hydraulic fluid accumulator and a fluid outlet for degassed hydraulic fluid from the hydraulic fluid accumulator.

9. The apparatus according to claim 8, wherein the vacuumizing arrangement of the device is configured to be coupled with the hydraulic circuit.

10. The apparatus according to claim 8, wherein the device is configured with a filter pump unit for the separate hydraulic fluid accumulator.

Description

[0034] The invention and the technical environment are explained in greater detail below with the help of figures. In these, the same components are identified using the same reference numbers. The illustrations are schematic and are not provided to depict relative sizes. The comments made with reference to individual details of one figure can be extracted and freely combined with features of other figures or the foregoing description, unless something compellingly different emerges for a person skilled in the art or a combination of this kind is explicitly prohibited here. The drawing shows schematically:

[0035] FIG. 1: a side view of the electrohydraulic system with a hydraulic axle and a closed hydraulic circuit with the process valve closed;

[0036] FIG. 2: a block diagram with a device for evacuating and filling a closed hydraulic circuit with degassed hydraulic fluid and flow directions of fluids;

[0037] FIG. 3: a circuit diagram of a hydraulic axle with a hydraulic circuit for a closed hydraulic circuit and

[0038] FIG. 4a, 4b: a front view (FIG. 4a) and a side view (FIG. 4b) of a device for degassing a hydraulic fluid and for filling a closed hydraulic circuit.

[0039] FIG. 1 shows an electrohydraulic system 7 with a hydraulic axle as the hydraulic consumer and a closed hydraulic circuit with the process valve 1 closed.

[0040] FIG. 1 shows an electrohydraulic actuating drive 29 for a process valve 1 having a process valve housing 2 through which a process valve channel 3 passes, which is continued at its outlets by pipes which are not shown, and in which a gaseous or liquid medium flows from the sea bed to part of a drilling rig projecting from the sea or to a drilling vessel. The flow direction is indicated by arrow 4.

[0041] A cavity is formed in the process valve housing 2 which crosses the process valve channel 3 and in which a process valve slide 5 with a discharge opening 6 can be moved transversely to the longitudinal direction of the process valve channel 3. In the state according to FIG. 1, the process valve channel 3 and the discharge opening 6 do not overlap in the process valve slide 5. The process valve 1 is therefore closed. In a state (not shown) the discharge opening 6 and the process valve channel 3 largely overlap. The process valve 1 is almost closed.

[0042] A process valve 1 of the kind shown and the use described is intended, on the one hand, to be capable of being actuated in a controlled manner and, on the other, also to contribute to safety, in that it adopts a position which corresponds to a safe state quickly and reliably in the event of a fault. In the present case, this safe state is a closed process valve 1.

[0043] The process valve 1 is actuated by a compact electrohydraulic system 7 which is arranged underwater right on the process valve 1. The hydraulic system 7 has a container 9 which is fastened to the process valve 1 on an open side, so that there is an interior 10 which is closed off from the environment and which is filled with a hydraulic pressure fluid, for example oil, as the working medium. For fastening to the process valve housing 2, the container 9 has on its open side an inner flange by means of which it is screwed to the process valve housing 2. A continuous seal 11 which is inserted into a circumferential groove in the process valve housing 2 is arranged radially outside the screw connections between the inner flange of the container 9 and the process valve housing 2.

[0044] The container 9 is pressure-compensated in respect of the ambient pressure prevailing underwater (seawater region 12). For this purpose, a membrane 14 is tightly clamped in an opening in the container wall in the case of a pressure compensator 13. The membrane 14 means that the interior 10 is partitioned off from the environment. A cable 8 is conducted out of the container 9.

[0045] In the interior 10 of the container 9, there is a hydraulic cylinder 15 (as a hydraulic consumer or actuating axle) with a cylinder housing 16 which is closed on the end face by a cylinder base 17 and a cylinder head 18, with a piston 19 that can be displaced inside the cylinder housing 16 in the longitudinal direction of the cylinder housing 16 and with a first piston rod 20 fixedly connected to the piston 19 and projects away from the piston 19 on one side, which piston rod 20 passes through the cylinder head 18 in a sealed and guided manner not depicted in greater detail. The gap between the piston rod 20 and the cylinder head 18 is sealed off by two seals (not shown) arranged in the cylinder head 18 at an axial distance from one another. The process valve slide 5 is fastened to the free end of the piston rod 20. Furthermore, there is a second piston rod 21 which is fixedly connected to the piston 19 and projects away from the piston 19 on the other side and which is guided in a sealed manner and passes through the cylinder base 17. The piston 19 divides the inside of the cylinder housing 16 into a first cylinder chamber 22 on the cylinder head side and a second cylinder chamber 23 on the base side, the volume of which second cylinder chamber depends on the position of the piston 19.

[0046] A helical compression spring 24 is housed in the cylinder chamber 22 and surrounds the piston rod 20 and is clamped between the cylinder head 18 and the piston 19, acts upon the piston 19 in a direction in which the piston rod 20 is retracted and the valve slide 5 is moved to close the process valve 1.

[0047] In the interior 10 of the container 9 is also located a hydraulic machine 25 which can be operated as a pump with two delivery directions. The hydraulic machine 25 has a pressure connection 26 and a suction connection 27 which is open to the inside 10. When operating as a pump, the hydraulic machine 25 can convey hydraulic fluid drawn from the interior 10 via the pressure connection 26 to the cylinder chamber 23. Conversely, hydraulic fluid can be displaced from the cylinder chamber 23 via the hydraulic machine 25 into the interior 10 of the container 9. An electrical machine 28 for a joint rotational movement is mechanically coupled with the hydraulic machine 25, for example via an axle.

[0048] Furthermore, a hydraulic coupling is present by means of which hydraulic fluid or oil degassed under water can be introduced from a first system (e.g. accumulator or refilling station or emergency actuation robot) into a second system (closed hydraulic circuit) without there being any contamination with seawater.

[0049] The hydraulic coupling comprises a block 33 and a hot stab (34). The block 33 is arranged in the interior 10 of the container 9, while in the example shown a stab-shaped filling part 35 is located within the block 33 and a connection part 36 outside the block 33. A remote-controlled underwater vehicle 37 which incorporates a storage container 38 for degassed hydraulic fluid or oil as the hydraulic reservoir is connected to the connection part 33. A regulating device for the oil flow from the underwater vehicle 37 to the coupling is identified as 39. The regulating device 39 comprises, or is connected to, a switch-on and switch-off device for the flow of degassed fluid from the storage container 38. An outlet region is identified as 40.

[0050] The underwater vehicle 37 may be configured as a Remote Operated Vehicle (ROV), an Autonomous Underwater Vehicle (AUV) or a Subsea Crawler (e.g. mining or cable-laying).

[0051] A (hydraulic) arrangement of the kind presented here can be installed in a new (hydraulic) device or retrofitted in an existing (hydraulic) device.

[0052] FIG. 2 shows a block diagram with an apparatus for setting up an electrohydraulic system. A device 41 for providing degassed hydraulic fluid is connected to a vacuum pump or vacuumizing arrangement 43 which is used to degas the hydraulic fluid. In addition, the hydraulic circuit 42 is optionally connected to the same vacuum pump or vacuumizing arrangement 43 which can be used to evacuate the hydraulic circuit 42. Two separate vacuum pumps (not shown) may also each be attached to the device and to the closed hydraulic circuit 42. Furthermore, an emptying device 44 is connected to the hydraulic circuit 42 which is used to empty used oil. In addition, a venting device 45 may be attached to the hydraulic circuit 42. The arrows 46 and 47 each designate a hydraulic fluid flow and arrows 48, 49, 50 each denote an air flow. The arrow tips each indicate the flow direction.

[0053] FIG. 3 shows a circuit diagram of a hydraulic axle 51 with a hydraulic circuit for a closed hydraulic circuit. A compact axle is depicted in FIG. 3. In this case, a hydraulic pump, an electric motor and a multi-face cylinder are assembled to form a structural unit. In order to control the multi-face cylinder, a plurality of control valves is provided in the control block.

[0054] The hydraulic axle 51 (servo-hydraulic compact axle) has a control block 52 to which a hydraulic cylinder 54 is attached via an intermediate block 53. A hydraulic machine 55 is furthermore connected to the control block 52 which can be used in both directions as a hydraulic pump and hydraulic motor. The hydraulic machine 55 can be driven via a drive in the form of an electric motor 56. Furthermore, a hydraulic accumulator 57 is connected to the control block 52.

[0055] The hydraulic cylinder 54 is a multi-face cylinder, the piston 58 of which has an extension surface 59, a first retraction surface 60 and a second retraction surface 61. Via the control block 52 and the intermediate block 53, the piston 58 can be extended and retracted in speed mode and in power mode. Furthermore, decompression can take place following the power mode in an extending and retracting direction. Furthermore, the piston 48 can be clamped in a pressure retention phase. Moreover, an accumulator loading mode may be provided.

[0056] The hydraulic machine 55 is connected to the control block 2 via a first pump connection 62 and a second pump connection 61. The first pump connection 62 can be fluidically connected via a first control valve 64 of the control block 52 to the extension surface 59. The first control valve 64 is configured as a switching valve, wherein the valve slide thereof is acted upon with a spring force in its closing position via a valve spring and can be moved into its opening position via an electromagnetic actuator or manually. The second pump connection 63 can be fluidically connected to the second retraction surface 61 via a second control valve 65 which is configured according to the first control valve 64. Via a third control valve 66 which is configured according to the control valves 64 and 65, the extension surface 59 can be fluidically connected to the first retraction surface 60. A flow path between the first pump connection 62 and the first control valve 64 can be fluidically connected to the hydraulic accumulator 57 via a fourth control valve 64. In addition, the hydraulic accumulator 57 can be connected via a first non-return valve 60 to the first pump connection 62 and via a second non-return valve 69 to the second pump connection 63. The non-return valves 68, 69 in this case each open in a flow direction away from the hydraulic accumulator 57. Furthermore, the first pump connection 62 is connected via a pressure-limiting valve 70 and the second pump connection 63 via a pressure-limiting valve 71 to the hydraulic accumulator 57. Moreover, the extension surface 59 can likewise be fluidically connected via a pressure-limiting valve 72 and the second retraction surface 61 via a pressure-limiting valve 73 to the hydraulic accumulator 57. Two switching valves 74, 75 are arranged in series in the intermediate block 53. In this case, they are configured according to the control valves 64 to 67. Via the switching path valves 74, 75, a pressure medium connection between the second pump connection 63 and the first retraction surface 60 can be opened and closed. The pressure medium connection in this case is opened when both switching path valves 74, 75 are switched in their opening position.

[0057] If the hydraulic cylinder 54 is arranged in a suspended manner, the piston 58 can be held high when the switching path valves 74, 75 are in the closed state via the switching path valves 74, 75. Consequently, they can be used as high-retaining valves to protect an annular chamber of the hydraulic cylinder 54 which is delimited by the first retraction surface 60 and can be used as a press cylinder. The second switching path valve 75 is disposed between the switching path valve 74 and the hydraulic cylinder 54. In turn, a pressure-limiting valve 76 is connected between the first retraction surface 60 and the second switching path valve 75. Said pressure-limiting valve is arranged in the intermediate block 53 and connected to the hydraulic accumulator 57 via the control block 52.

[0058] The intermediate block 53 also has a first connection surface 77 and a second connection surface 78. In this case, the first connection surface 77 is connected to a connection surface 79 or end face of the control block 52. The hydraulic cylinder 54 is in turn connected to the second connection surface 78. The connection surfaces 77, and 79 have an identical hole pattern in this case. Consequently, the hydraulic cylinder 54 could also be directly connected to the control block 52 without an intermediate block 53.

[0059] A filter is identified as 80 and non-return valves as 81 to 84 (without pressure drop).

[0060] FIGS. 4a, 4b show schematically as a front view (FIG. 4a) and as a side view (FIG. 4b) a device 41 for providing degassed hydraulic fluid and for filling a closed hydraulic circuit 42 (see FIG. 2) with the degassed hydraulic fluid.

[0061] The degassed oil required for filling a hydraulic system can be prepared for use by means of the device 41. Evacuation of the hydraulic bores in the control block, the interiors of the superstructures and the cylinder (electrohydraulic system) is possible using the device 41. Filling with the prepared hydraulic fluid is possible thereafter. If the device 41 is connected to a hydraulic system with pressure-resistant hydraulic hoses 88 which are not shown, said system can be flushed and the hydraulic fluid in the secondary flow can be evacuated and filtered.

[0062] The volumetric flow of the installed pump (filter pump 92) is at most 7.5 l/min. The operating temperature falls within the range of +10 C. to 60 C. Pressure fluids with a viscosity of 10 to 300 m.sup.2/s are suitable.

[0063] The device 41 comprises a container or separate hydraulic fluid accumulator 90 (oil container) which is vacuum-tight and pressure-tight. A filter pump unit (or circulation pump) 91 is mounted on the lower part of the hydraulic fluid accumulator 90 and is supplied with a bypass pipe 89 of 3 bar to the hydraulic fluid accumulator 90 (tank). The filter pump unit 91 comprises an electrically operated filter pump 92, for example an internal gear pump, having an exchangeable low-pressure filter which is monitored by means of an optical maintenance display. An electric motor (main pump motor) is identified as 93 and a line filter as 94.

[0064] A low-pressure distributor block is provided with the filter pump unit 91 and the upper part of the hydraulic fluid accumulator 90. The distributor block carries low-pressure plug-in connections (e.g. for filling a hydraulic system) which can be connected using ball cocks and a leak-free hydraulic quick-action coupling for refilling. A movable frame carries the hydraulic fluid accumulator 90 with the filter pump unit 91 and the distributor block and a vacuum pump or vacuumizing arrangement 43. This vacuumizing arrangement 43 is connected to the upper part of the hydraulic fluid accumulator 90 via an oil separator by means of a low-pressure hose. With a 3/2-way functional ball cock 97 (3-way ball cock), the hydraulic fluid accumulator 90 can be connected to the atmosphere or to the vacuum pump or vacuumizing arrangement 43. The pressure hoses are each fitted with a hydraulic quick-action coupling at the end. A coupling sleeve (hydraulic filling) is identified as 96.

[0065] The hydraulic machine 25; 55 is shown in FIG. 1 as a hydraulic pump with two delivery directions and in FIG. 3 as a hydraulic pump and/or hydraulic motor. The hydraulic consumer 86 is shown in FIG. 1 as a double-acting hydraulic cylinder 15 with a two-sided piston rod and in FIG. 3 as a multi-face cylinder. The hydraulic reservoir 87 is shown in FIG. 1 as a container 9 and in FIG. 3 as a hydraulic accumulator 57.