Actuating arrangement, switching drive for such an actuating arrangement and valve arrangement for such an actuating arrangement

Abstract

Actuating arrangement with a control drive (8) for actuating a control element, for example a valve (4) controlling a process flow or an actuator for adjusting a device, with an electric actuator for proportionally actuating the control element in one direction of action, wherein an emergency actuating device (12) for resetting in the event of a fault opposite to the direction of action is assigned to it, wherein the emergency actuating device (12) has a pre-tensioned energy storage device (66) whose stored energy can be used for resetting, and with a switching drive (18) for actuating a switching element provided in series with the control element, for example a switching valve (6) or a switching actuator, which can be reset in the event of a fault opposite to the direction of action via a switching energy storage device (30) pre-tensioned in the opposite direction of action, wherein the control drive (8) and the switching drive (18) are hydraulically coupled,wherein the switching energy storage device (30) is a spring storage device (32) which is actuated in the return direction by means of a piston (36), wherein the piston (36) delimits a pressure chamber (24) which can be pressurized with low pressure for discharge, with a pump unit (40, 84) for pressurizing the pressure chamber (24) with a clamping pressure, wherein the pump unit (40, 84) is associated with a check valve (52) which prevents a flow of pressure medium to the pump unit (40, 84) in normal operation of the clamping arrangement.

Description

The invention relates to an adjusting arrangement having a control drive for actuating a control element, to a switching drive provided for such an adjusting arrangement, and to a valve arrangement having such an adjusting arrangement.EP 1 413 810 A1 discloses a generic actuating arrangement for a turbine valve for controlling the gas or steam supply of a turbine or for a process fitting for controlling a process flow or for pitch adjustment of a wind turbine or the like. Such adjusting arrangements usually have an adjusting drive which, in the subject matter of EP 1 413 810 A1, is designed as an electric spindle drive. In a gas turbine, for example, an opening cross section of a fitting for adjusting the gas supply can be adjusted by means of such an adjusting arrangement. In an emergency, for example in the event of a power failure or a malfunction, the fitting should be reset in order to avoid damage to the installation. For this purpose, in the known solution, a toggle lever mechanism is assigned to the spindle drive, which during regular operation, i.e. with adequate power supply, is locked in an extended position in which a biasing spring is tensioned. This toggle lever acts on a valve body of the fitting (in the case of a gas turbine) or on the adjustment mechanism for setting the pitch angle in the case of a wind turbine. The locking of the toggle lever takes place only when there is sufficient power supply-in the event of a power failure-the locking mechanism releases the toggle lever, so that it is adjusted from its extended position into its bent position via the biasing spring and the valve member-or generally speaking-is adjusted back into its predetermined basic position in accordance with this adjustment path.A disadvantage of such a solution is that the toggle lever mechanism requires considerable installation space and is furthermore relatively complex in construction, so that the outlay on apparatus is considerable.German patent application DE 10 2008 036 980 A1 of the applicant discloses a generic actuating arrangement in which a hydraulically prestressed emergency actuating device is used instead of the toggle lever. A piston is thereby acted upon by a force in the restoring direction via a spring or another energy store. The piston furthermore delimits a pressure chamber which can be pressurized with a hydraulic pressure for charging / tensioning the energy store and, in the case of an emergency actuating device, can be connected to low pressure, so that the energy stored in the energy store can be used for resetting the actuating drive. With regard to further details of this actuating arrangement, for the sake of simplicity, reference is made to the abovementioned post-published patent application, the disclosure of which is part of that of the present application.DE 101 52 414 A1 discloses an energy cylinder for actuating a valve of a turbine, in particular of a steam turbine, in which a cylinder housing and a control block are combined to form a common block, resulting in an extremely compact construction.The invention is based on the object of further improving the operational reliability of such an adjusting arrangement.This object is achieved by an actuating arrangement having the features of patent claim 1, a switching unit according to patent claim 12 and a valve arrangement having the features of independent patent claim 13.The adjusting arrangement according to the invention for actuating a control element, for example a valve controlling a process current or an actuator for adjusting a device, for example a pitch adjustment of a wind turbine or the like, has a regulating drive with an electric actuating drive, by means of which the control element (valve / actuator) can be adjusted in a first active direction by means of an actuating element. The control element is assigned an emergency actuation device for resetting the actuator in the event of a fault counter to the direction of action. This emergency activation device has a prestressed energy store, the stored energy of which can be used for resetting. Furthermore, in series with the control element, a switching element, for example a switching valve or a switching actuator, is provided, which is hydraulically prestressed via a switching energy store into a position corresponding to the active direction and can be reset counter to the active direction in the event of a fault.In other words, according to the invention, a control drive formed by the control element with an electric drive and emergency actuation device is assigned a switching drive which is likewise reset for emergency actuation, so that the process current controlled by the control element or the device adjusted by an actuator is additionally reset in the event of a fault via the switching element.The switching energy store is a spring store, the piston of which is loaded in the restoring direction by means of a spring and which delimits a pressure chamber which is connected to low pressure for discharging. Such a hydraulically prestressed spring accumulator is of extremely simple and compact construction, so that the investment costs are minimal and adequate functioning can be ensured even under unfavourable operating conditions. The actuation of the switching energy store is effected via a pump assembly.In order to prevent a return flow of pressure medium to the pump assembly, according to the invention, a shut-off valve preventing a pressure medium flow from the energy store or from the switching energy store to the respective pump assembly can be assigned to the pump assembly.In a variant of the invention, the pressure chamber prestressing the switching energy accumulator can be connected to a low-pressure (LP) switching hydraulic accumulator via a pressure line and a normally open switching valve. During regular operation of the system, this switching valve is energized, so that the pressure medium connection to the hydraulic accumulator is shut off and the switching energy accumulator remains charged.In a variant of the invention, this pump assembly is formed by a clamping pump, the high-pressure connection of which can be connected to the pressure chamber. The clamping pump can be assigned to the switching energy storage unit alone or both to the latter and to the energy storage unit of the regulating unit.In the case of increased requirements for safety, a redundant clamping pump can be assigned to the clamping pump.In one exemplary embodiment, it is preferred to provide a circulation line with a circulation valve in order to connect the pumps to their pressure connection with low pressure in order to start up.In an embodiment of particularly simple construction, the pump assembly is formed by a capture cylinder for damping the movement of the control element in an end position region. This catching cylinder acts as a piston pump which is actuated by the electric actuating drive of the actuating arrangement.In an especially simple embodiment, this catching cylinder is designed as a differential cylinder.In order to avoid a mechanical overload of the components, the switching energy store can be designed with end position damping.Other advantageous developments of the invention are the subject matter of further dependent claims.Preferred exemplary embodiments of the invention are explained in more detail below with reference to schematic drawings. The following are shown: FIG. 1 shows a greatly simplified circuit diagram of an actuating arrangement according to the invention with a regulating unit and a switching unit; FIG. 2 is a schematic diagram of a switching device for an adjusting arrangement according to FIG. 1 ; FIG. 2.1 shows a variant of the circuit from FIG. 2 ; FIG. 3 shows a further exemplary embodiment of an actuating arrangement with hydraulically coupled regulating and switching unit; FIG. 4 shows a variant of the embodiment according to FIG. 3 with an integrated pump, and FIG. 5 shows a further exemplary embodiment of an actuating arrangement with a pump assigned to the control unit.The invention is explained below with reference to some exemplary embodiments in which the adjusting arrangement according to the invention is used for adjusting a gas or steam volume flow of a gas or steam turbine. In principle, however, the adjusting arrangement according to the invention can be used generally in fittings for controlling process fluids, in pipelines, in pressure changing or distributing stations or, even more generally, in devices in which, for safety reasons, a return adjustment to a predetermined operative position must take place in the event of a fault, stored energy then being used for the return. These can be linear or rotational movements.FIG. 1 shows a greatly simplified schematic diagram of a gas turbine 1, the gas volume flow of which can be adjusted via an adjusting arrangement 2 according to the invention with a gas turbine control valve 4 and a gas turbine switching valve 6. The control valve 4 is actuated via a control drive 8, via which the opening cross section of the control valve 4 can be adjusted proportionally in order to control the gas supply to the gas turbine 1. The control drive 8 essentially comprises an electrically driven spindle drive 10, by means of which a valve body of the control valve 4 can be adjusted. In the event of a fault, for example a power failure, the control valve 4 could not be reset via the electric spindle drive 10-this resetting takes place according to the invention via an emergency actuating device 12 which substantially comprises a hydraulically prestressed spring accumulator. In the event of a power failure, the spring accumulator of the emergency activation device 12 is unlocked, so that the fitting is moved back into its closed position. In order to avoid excessive acceleration of the fitting, the emergency actuation device 12 is assigned a damping device 16, by means of which the movement of the fitting in the region of the end position is damped. The gas turbine switching valve 6 is actuated by means of a switching drive 18, which maintains the switching valve 6 in an open position during regular operation of the gas turbine 1. In the event of a fault, for example the above-described power failure, the switching valve 6 is shut off via the switching drive 18, so that the gas supply via the gas line 21 is shut off by two devices which act independently of one another. In the described exemplary embodiments, the switching drive 18 essentially consists of a spring accumulator 20, which is prestressed by a piston 22. This pressure is in turn acted upon by the pressure in a pressure chamber 24 in the prestressing direction. In the event of a fault, this pressure chamber 24 is connected to low pressure, so that the switching valve 6 is moved from its opening position into the above-described blocking position by the force of the spring accumulator 20.FIG. 2 shows a detailed circuit diagram of a switching drive 18 as can be used in an actuating arrangement 2 according to FIG. 1.According to FIG. 2, the switching drive 18 engages a switching driver 26 which is connected to the valve body, not shown, of the switching valve 6 and carries along its opening and closing movement. In the orientation selected in FIG. 2, the opening of the switching valve 6 takes place by adjusting the driver 26 downward, while the closing movement takes place by adjusting the switching driver 26 upward (FIG. 2 ), wherein the closing stroke of the switching driver 26 is limited by striking a switching stop 28. The shifting drive 18 has a shifting energy store 30, which essentially consists of a spring store 32, which is hydraulically prestressed. This hydraulic prestress is effected via a clamping cylinder 34, in which a piston 36 is guided, which piston acts on the one hand on the spring accumulator 32 and on the other hand delimits the aforementioned pressure chamber 24 with the clamping cylinder 34. By building up a sufficient clamping pressure in the pressure chamber 24, the spring accumulator 32 is prestressed via the piston 36, wherein this prestressing force is designed such that it is sufficient to move the valve body, not shown, in its closing direction even in the case of high gas volume flows. This closing movement of the spring accumulator 32 is transmitted via the piston 36 and a piston rod 38 to the driver 26 and thus the valve member of the switching valve 6.The clamping pressure is applied via a clamping pump 40, the pressure connection of which is connected to the pressure chamber 24 via a pressure line 42. The suction connection of the clamping pump 40 is connected to a low-pressure (LP) switching hydraulic accumulator 44. In the exemplary embodiment shown, the clamping pump 40 is electrically driven, for example by an asynchronous motor 46-other motor types can of course also be used.As is further explained in FIG. 2, the clamping cylinder 34 is designed with an end position damping 48, in which the movement of the piston 36 is damped shortly before reaching the switching stop 28 by the pressure medium pushed out of the pressure chamber 24 having to flow out through a damping gap effective in the end position region. In order to facilitate filling in this end position range, the end position damping 48 is designed with a filling path bypassing the damping gap, in which a damping check valve 50 opening toward the pressure chamber 24 is arranged.In the pressure line 42 there is furthermore provided a nonreturn valve 52, which opens in the direction of the pressure chamber 24 and prevents the pressure medium from flowing back from the pressure chamber 24 to the clamping pump 40.In the pressure medium flow path between the check valve 52 and the pressure chamber 24, a relief line 54 branches off, bypassing the clamping pump 40 and opening into a suction line 55, via which the low-pressure hydraulic accumulator 44 is connected to the suction connection of the clamping pump 40. In the relief line 54, an electrically actuated switching valve 56 designed as a 2 / 2-way valve is provided, which is prestressed in a current-free manner into an open position and, when a switching magnet is energized, can be brought into a blocking position, in which the relief line 54 is blocked. This switching valve 56 is preferably designed as a seat valve in order to ensure a leakage-free shut-off of the pressure chamber 24. The switching valve 56 is preceded by a diaphragm 57.During normal operation of the gas turbine 1, the switching valve 56 is energized and is thus switched over into its blocking position, so that the relief line 54 is blocked. When the system is put into operation, the pressure chamber 24 is charged with the clamping pressure via the clamping pump 40, so that the spring accumulator 32 is prestressed in the manner described at the beginning. When the desired clamping pressure in the pressure chamber 24 is reached, the clamping pump 40 is switched off, so that the pressure medium in the pressure chamber 24 is blocked by the switching valve 56 and the check valve 52 and the spring accumulator 32 remains prestressed. This sufficient spring prestress can be monitored, for example, by a pressure transducer in the pressure chamber 24 or by a displacement transducer for detecting the piston stroke or the spring stroke.In the event of a power failure or the like, the switching valve 56 is not energized, so that it automatically switches over into its illustrated open position and the pressure chamber 24 is connected via the pressure line 42 (the damping gap of the end position damping 48 is not yet effective) and the opened relief line 54 to the low-pressure hydraulic accumulator 44, and the pressure in the pressure chamber 24 is thus reduced to the low-pressure hydraulic accumulator 44. The force of the spring accumulator 32 moves the piston 36 and thus the driver 26 in the closing direction of the switching valve 6, wherein the pressure medium is pushed out of the pressure chamber 24. As explained above, the end position damping 48 becomes effective shortly before reaching the switching stop 28, so that the movement speed of the piston 36 and thus of the driver 26 is damped. When the switching stop 28 is reached, the switching valve 6 is adjusted into its blocking position, so that the gas line 21 is blocked independently of the position of the control valve 4.After this emergency function, the spring accumulator 32 must then be recharged again in the manner described above.In principle, the adjustment of the driver 26 for opening and closing the valve member of the switching valve 6 can take place via the piston 36, wherein the opening movement then takes place by building up the clamping pressure in the pressure chamber 24, while the closing movement is initiated in the manner described above by de-energizing the switching valve 56. In this case, the piston rod 38 would then have to be connected to the driver 26.When using an external clamping pump 40 according to FIG. 2, the operator may demand that a redundant solution be created. Such a variant is shown in FIG. 2.1. In this exemplary embodiment, a redundant clamping pump 118 is provided in parallel with the clamping pump 40, which is designed with a hydraulic circulation circuit. In the solution specifically shown in FIG. 2.1, a redundancy line 120 branches off upstream of the check valve 42, which line leads into the suction line 55 and in which the redundant clamping pump 118 is provided, which is driven via a further pump motor, for example an asynchronous motor 119. In the line section between the pressure connection of the redundant clamping pump 118 and the check valve 52, a check valve 115 is provided which inhibits a return flow to the redundant clamping pump 118. A corresponding shut-off valve 116 is then provided in the pressure medium path between the pressure output of the clamping pump 40 and the opening of the redundancy line 120. In order to enable reliable starting of the clamping pumps 40, 118 even under load, a circulation line 122, which opens into the suction line 55 and in which a circulation valve 117 is provided, branches off in the region between the shut-off valves 52, 116. This is designed as a 2-way switching valve of seat construction and prestressed into a blocking position and can be switched over by energizing a switching magnet into a through position in which the pressure medium can be conveyed in a non-pressurized circulation. Incidentally, the embodiment corresponds to that of FIG. 2, so that further explanations are unnecessary.The switching valve 56 shown in FIGS. 2 and 2.1 is designed as a seat valve, but due to leakage the pistons 36 can execute a movement in the direction of the switching stop 28. This movement can be detected with suitable sensors. By energizing the circulating valve 117 and activating the clamping pump 40 and the redundant clamping pump 118, the pressureless starting of the two clamping pumps 40, 118 is made possible. Thereafter, by switching the circulation valve 117 off from current, the pressure chamber 24 can be pressurized and the piston 36 can be moved again in the direction of the switching stop 28, so that the spring accumulator 32 is charged. The switching valve 56 remains de-energized during the entire process. The shut-off valve 115 for the redundant clamping pump 116 prevents pressure medium from being conveyed from the clamping pump 40 to the redundant clamping pump 118. The shut-off valve 116 to the clamping pump 40 blocks the delivery of the pressure medium from the redundant clamping pump 118 to the clamping pump 40.In the exemplary embodiment according to FIGS. 2 and 2.1, the control valve 4 and the switching valve 6 are designed as components that act independently of one another. FIG. 3 shows an exemplary embodiment in which the control drive 8 and the switching drive 18 are hydraulically coupled.Details of the control drive 8 have already been explained in detail in the earlier patent application described at the beginning, so that only the components essential for understanding the invention are described here and reference is made otherwise to the earlier application.Accordingly, the not shown valve member of the control valve 4 is coupled to a driver 58, which in turn is adjusted by the spindle drive 10 in order to control the gas supply to the gas turbine 1. This spindle drive 10 comprises in a conventional manner a spindle nut 60 coupled, for example, to the driver 58, which spindle nut meshes with a spindle 62 rotatably mounted on a frame, not shown, which spindle is in turn driven by a spindle motor 64. When the spindle 62 is driven, the spindle nut 60 performs an axial stroke which is transmitted directly to the driver 58 and thus to the valve body of the control valve 4. The end stroke of the driver 58 in the closing direction is limited by a stop 65.In order to return the spindle drive 10 and thus the control valve 4 to its closed position in the event of a power failure, the driver 58 is operatively connected to the emergency actuating device 12 described at the beginning, the construction of which corresponds substantially to that of the switching drive 18. Accordingly, the emergency actuating device 12 has a spring accumulator, referred to below as spring 66, which is prestressed by an actuating piston 70 guided in an actuating cylinder 68. The latter defines with the actuating cylinder 68 a clamping chamber 72, in which a clamping pressure can be built up for clamping the spring 66. A piston rod 74 of the piston 70 protrudes in the axial direction from the actuating cylinder 68 and carries at its end section an impact spring 76, which is arranged at a distance from the driver 58 during normal operation, i.e. upon adjustment of the gas volume flow via the control drive 8.The pressure chamber 72 is connected via a line 78 to a connecting line 80 which opens into the pressure line 42. In this region of the connecting line 80 a connecting valve 82 is provided, which is designed as a 2 / 2-way valve and is prestressed in a non-energized manner into a blocking position. When a solenoid is energized, the connecting valve 82 can be switched over into an open position in which a pressure medium connection to the pressure line 42 is opened.For damping the end positions, the spindle drive 10 or the driver 58 is assigned as damping device 16 a catching cylinder 84, the catching piston 86 of which separates a cylinder space 88 on the bottom side from an annular space 90 traversed by a catching piston rod 89. Both pressure chambers are connected via a low-pressure line to a low-pressure accumulator 94 acting as a compensating container. The catching cylinder 84 is designed with an end position damping 96, the construction of which corresponds, for example, to the end position damping 48. Since the same pressure acts in both pressure chambers 88, 90, the capture piston rod 89 is acted upon in contact against the driver 58 due to the higher force acting in the extension direction.The low-pressure line 92 can be connected to the connecting line 80 via a channel 98 and a trap valve 100. The safety valve 100, which is designed as a 3 / 2-way valve, can be switched over by an actuating magnet and is prestressed in a current-free manner into an open position, in which the low-pressure line 92 is connected to the connecting line 80. A third connection of the trap valve 100 is shut off in this basic position toward the low-pressure line 92 and is connected to a storage line 102 which opens into the annular chamber 90.When the capture valve 100 is energized, this storage line 102 is connected via the channel 98 to the low-pressure line 92, while the connection to the connecting line 80 is shut off. In the pressure medium flow path between the connecting line 80 and the capture valve 100, a damping orifice 104 is provided in the solution shown.The construction of the switching unit 18 corresponds substantially to the exemplary embodiment according to FIG. 2, with the exception that in the solution according to FIG. 3 a damping orifice 106 and a shut-off valve 108 are provided in the pressure line 42. The latter is designed as a 2 / 2-way valve which is prestressed into an open position and is switched over by energizing a solenoid into a blocking position in which the pressure medium is blocked in the pressure chamber 24. As already indicated, all the switching valves 82, 100, 108 are designed as seat valves in order to ensure a leak-free shut-off of the respective pressure medium paths.During regular operation, the adjustment of the control valve 4 takes place solely via the spindle drive 10 by actuating the electric spindle motor 64; in this case, the solenoids of the valves 56, 82, 100, 108 are energized, so that the pressure medium is clamped in the pressure chambers 72, 24 and the two spring accumulators 32, 66 are charged accordingly. The switching valve 6 is switched to its open position. The annular chamber 90 of the catching cylinder 84 is connected via the accumulator line 102 and the switched-over catching valve 100 directly with the low-pressure accumulator 94 when the end position damping 96 is bypassed, so that the piston 86 can follow the actuating movement of the driver 58 almost without losses. During the normal function of the adjusting arrangement 1, the impact spring 76 is always at a distance from the driver 58.In the event of a power failure or malfunction, the spindle drive 10 remains stationary due to the non-energization of the electric spindle motor 64, so that the regulating valve 4 can no longer be reset by actuating the spindle drive 10. In the event of such an emergency, the valves 56, 82, 100, 108 are de-energized, so that they are switched to their respective basic position. In this case, the pressure medium connection of the accumulator line 102 to the low-pressure accumulator 94 is shut off via the safety valve 100, so that the end position damping 96 of the safety cylinder 84 becomes effective. Furthermore, the clamping chamber 72 of the actuating cylinder 68 is connected to the low-pressure accumulator 94 via the capture valve 100, so that the actuating piston 70 is extended by the force of the spring 66 and, in the process, pressure medium is pushed out of the clamping chamber 72 to the low-pressure accumulator 94. The hydraulic coupling between the switching valve 6 and the regulating valve 4 is shut off by the shut-off valve 82. After a certain stroke of the actuating piston 70, the impact spring 76 runs onto the driver 58 and is further compressed by the substantially greater force of the spring 66 until the driver 58 is finally carried along in the closing direction, so that the control valve 4 is controlled accordingly. After a certain stroke, the driver 58 runs onto the stop 65, wherein the end position damping 96 is effective in this end stroke range, so that the adjusting movement of the driver 58 is decelerated and the driver 58 runs comparatively gently onto the stop 65.Parallel to this restoring movement of the control valve 4, the switching valve 6 is also switched over into its closed position. In this case, the force of the spring 32 moves the piston 36 in the extension direction, wherein the driver 26 coupled to the valve body of the switching valve 6 is adjusted in the closing direction. The pressure chamber 24 is connected to the low-pressure hydraulic accumulator 44 via the open shut-off valve 108 and the open switching valve 56, so that the pressure medium is pushed out of the pressure chamber 24 to the low-pressure hydraulic accumulator 44 by the force of the spring 32 - the driver 26 moves in the direction of the stop 28, wherein the adjusting movement is braked by the end position damping 48 shortly before it runs onto the stop 28. By this resetting of the switching valve 6, the gas line 21 is additionally shut off.When the system is restarted, the two spring accumulators 32, 66 must be recharged. In this case, either both spring accumulators can be charged simultaneously or in each case only one of the spring accumulators can be charged. In all cases, the charging takes place via the clamping pump 40.In the case in which both the spring accumulator 32 and the spring 66 are to be tensioned, the shut-off valve 108 remains de-energized, while the three other valves 56, 82 and 100 are energized and are thus switched into their respective switching position. When the clamping pump 40 is activated, pressure medium is then conveyed via the pressure line 42 to the pressure chamber 24 and via the opened connecting valve 82, the connecting line 80 and the line 78 into the clamping chamber 72, so that the pistons 36, 70 retract via the pressure applied by the clamping pump 40 and the springs 32, 66 are accordingly tensioned. After the desired prestress has been set, all valves 56, 82, 98, 108 are not energized, so that both the regulating drive 8 and the switching drive 18 are ready for operation again.In the case in which only the spring accumulator 32 has to be tensioned, the connecting valve 82 and the shut-off valve 108 are switched to zero current and the switching valve 56 is energized-the position of the trap valve 100 is thereby unimportant. By activating the clamping pump 40, the pressure medium is then only conveyed into the pressure chamber 24.For tensioning the spring 66, all valves 82, 56, 108, 100 are energized in a corresponding manner and the tensioning pump 40 is actuated. The pressure medium connection to the pressure chamber 24 is shut off via the shut-off valve 108, while the pressure medium connection to the clamping chamber 72 is open via the connecting valve 82. The respective pressure medium connections to the low-pressure accumulators 44, 94 are shut off via the valves 56 and 100, respectively. Accordingly, pressure medium is then conveyed into the clamping chamber 72 via the pump 40 and the spring 66 is correspondingly charged.In the exemplary embodiment described above, the switching unit 18 is assigned its own clamping pump 40. FIG. 4 shows a variant in which the function of the clamping pump 40 is taken over by the catching cylinder 16. The basic structure of the exemplary embodiment shown in FIG. 4 corresponds largely to that of FIG. 3, so that only the differences will be discussed.In the variant shown in FIG. 4, too, the shut-off valve 108 is provided in the pressure line 42 leading to the pressure chamber 24 of the clamping cylinder 34, which valve is prestressed in a non-energized manner into an open position and can be switched over by energizing the switching magnet into a leak-free switching position in which the pressure medium is confined in the pressure chamber 24. The connecting line 80 is connected to the other connection of the shut-off valve 108, which in this variant leads directly into the low-pressure line 92 leading to the low-pressure accumulator 94. In the pressure medium flow path between the opening of the connecting line 80 and the low-pressure accumulator 94, a closing valve 110 is arranged which is designed as a 2 / 2-way valve and is prestressed in a non-energized manner into an open position and can be switched over into a closed position by energizing an electromagnet. This closing valve 110 does not necessarily have to be designed as a seat valve.According to the exemplary embodiment according to FIG. 3, the two pressure chambers 88, 90 of the capture cylinder 84 are likewise connected to the low-pressure line 92, wherein a nonreturn valve 112 which opens in the direction of the annular chamber 90 is provided in the branch leading to the latter and, similar to the nonreturn valve 50, permits a flow of pressure medium towards the annular chamber 90 ( 24) and blocks it in the opposite direction. The annular chamber 90 of the capture cylinder 84 and the clamping chamber 72 of the actuating cylinder 68 are connected, as in the exemplary embodiment according to FIG. 3, via the lines 102 and 78, respectively, to the corresponding connections of the capture valve 100, the output connection of which is connected via the channel 98 to the low-pressure line 92.With regard to the regular function of this control arrangement, there is no difference from the solution described above-the switching valve 6 is in its open position, while the gas volume flow to the turbine 1 is controlled via the control drive 8. The two springs 32, 66 are prestressed, wherein the pressure medium is clamped in the pressure chambers 24, 72 by energizing the valves 100, 108.In the event of a power failure, the spindle motor 64 can no longer be actuated, the valves 100, 108 and 110 are each switched to their basic position. The pressure chamber 24 is connected to the low-pressure accumulator 94 via the open shut-off valve 108 and the closing valve 110. Accordingly, the clamping chamber 72 of the actuating cylinder 68 is likewise connected to the low-pressure accumulator 94 via the line 78, the capture valve 100, the channel 98 and the opened closing valve 110, with the result that the two drivers 26, 58 are adjusted substantially simultaneously in the direction of the closing position and, accordingly, both the switching valve 6 and the regulating valve 4 are reset in order to block the gas supply to the gas turbine 1.As soon as the power supply is ensured again, the emergency activation device 12 of the control drive 8 and the switching drive 18 of the switching valve 6 must first be tensioned. In the exemplary embodiment shown in FIG. 4, the respective pressure chambers 72, 24 are pressurized via the catching cylinder 84, the piston 86 of which is extended or retracted via the spindle drive 10.To prepare the pumping function, the two valves 110, 108 and 100 are first switched off. The spindle motor 64 is then controlled in such a way that the catching piston 86 performs a retraction movement ((-) in FIG. 4 ), so that the pressure medium is pushed out of the reducing cylinder space 88. As soon as the piston 86 has reached its predetermined reversal point, the spindle motor 64 is reversed in the rotational direction and the two valves 100, 108 are energized for drawing pressure medium into the cylinder chamber 88, so that the pressure medium connection between the low-pressure accumulator 94 and the two pressure chambers 72, 24 is shut off. By reversing the direction of rotation of the spindle motor 64, the piston 86 is extended ((+) in FIG. 4 ) so that pressure medium is sucked from the low-pressure accumulator 94 into the cylinder chamber 88, wherein the pressure medium is pushed out of the reducing annular chamber 90 via the accumulator line 102 and the capture valve 100 and is summed to form the volume flow flowing to the cylinder chamber 88.The pressure medium accommodated in the cylinder chamber 88 can then be supplied either to one of the pressure chambers 24, 72 or both together.To tension the spring accumulator 32 of the switching drive 18, the shut-off valve 108 is switched to the zero current state, while the two other valves 100, 110 are energized. The direction of rotation of the spindle motor 64 is reversed with respect to the above-described suction process, so that the piston 86 retracts and the pressure medium is correspondingly conveyed from the cylinder chamber 88 via the low-pressure line 92, the connecting line 80, the opened shut-off valve 108 and the pressure line 42 into the pressure chamber 24. After the pressure medium is pushed out of the cylinder chamber 88, the above-described suction process is again carried out by energizing the trap valve 100 and the shut-off valve 108 and by deenergizing the closing valve 110. Subsequently, the pressure medium is displaced into the pressure chamber 24 in the manner described above. This process is repeated until the spring accumulator 32 is charged.For charging the spring 66 alone after the preparation of the pumping function, the shut-off valve 108 remains in its energized shut-off position. The closing valve 110 is energized, so that the pressure medium is pushed out of the cylinder chamber 88 when the capture valve 100 is not energized and is conveyed into the clamping chamber 72 via the low-pressure line 92, the capture valve 100 and the line 78. In this case, too, the above-described pumping operation is repeated until the spring 66 is prestressed.For the simultaneous charging of both spring accumulators 32, 66, after the suction of pressure medium, the shut-off valve 108 and the safety valve 100 are switched off, while the closing valve 110 is switched over into its shut-off position, so that the pressure medium is pushed out of the cylinder chamber 88 by corresponding actuation of the spindle motor 64 and is conveyed in parallel into the two pressure chambers 24, 72. This pumping process is also repeated until the two spring accumulators 32, 66 are charged.The above-described variant requires minimal technical outlay in terms of apparatus-but the charging of the spring accumulators is comparatively complicated, the control valve 4 having to be controlled open and closed a number of times.FIG. 5 shows an exemplary embodiment in which the clamping pump 40 is arranged on the control valve side.The basic design of this variant shown in FIG. 5 corresponds largely to the embodiment shown in FIG. 4, wherein, in contrast to the exemplary embodiment according to FIG. 4, the connecting line 80 does not open directly into the low-pressure line 92 but is connected to the line 78 which leads to the clamping chamber 72 of the actuating cylinder 68. In this line 78, a shut-off valve 114 is arranged, which is designed as a 2 / 2-way valve and is prestressed into an open position and can be switched over into a shut-off position when current is supplied. In this blocking position, the pressure medium is clamped in the clamping chamber 72.As in the exemplary embodiment according to FIG. 4, the line 78 is connected to a connection of the trap valve 100. A second connection of the capture valve 100 is connected to the storage line 102 of the capture cylinder 84, as in the exemplary embodiments described above. The third connection of the trap valve 100 is connected via the channel 98 to the low-pressure line 92 leading to the low-pressure accumulator 94. In the exemplary embodiment shown, this low-pressure accumulator 94 is connected to the suction connection of the clamping pump 40, the pressure connection of which is connected to the connecting line 80 and the line 78. In the pressure medium flow path from the pressure connection of the clamping pump 40 to the valves 108, 114, the check valve 52 already illustrated in FIGS. 2 and 3 is arranged, which check valve allows a pressure medium flow in the direction of the pressure spaces 24, 72 and shuts off in the opposite direction to the clamping pump 40.The switching valve-side LP switching hydraulic accumulator 44 is connected to the pressure line 42 via the relief line 54 and the switching valve 56. In this, similar to the exemplary embodiment according to FIG. 3, a damping diaphragm 106 is arranged. Furthermore, in this exemplary embodiment, the clamping cylinder 34 is designed with an end position damping 48. Otherwise, the exemplary embodiment shown in FIG. 5 corresponds to the variants according to FIGS. 3 and 4, so that further explanations are unnecessary.The normal control function of the control arrangement 2 takes place in the manner described above, wherein the switching valve 6 is opened via the switching drive 18 and the gas volume flow takes place by adjusting the control valve 4 via the spindle drive 10.In the event of a fault, the valves 56, 100, 108, 114 are switched off, so that the low-pressure accumulator 94 is connected to the clamping chamber 72 via the low-pressure line 92, the capture valve 100 and the shut-off valve 114. The pressure chamber 24 of the clamping cylinder 34 is connected via the pressure line 42 and the opened switching valve 56 to the low-pressure hydraulic accumulator 44. In this configuration, the spring accumulators 32, 66 can extend the associated pistons 36, 70, so that the pressure medium is pushed out of the respective pressure chambers 24, 72 to the respectively associated low-pressure accumulator 44, 94. The force of the spring accumulators 32, 66 then moves the associated drivers 26, 58 in the direction of the respective stops 28, 65, so that the switching valve 6 is switched over into its blocking position and the regulating valve 4 is moved back into its closed position, wherein-as in the previously described exemplary embodiments-the spindle drive correspondingly rotates as well-this is possible due to the non-self-locking thread engagement between the spindle nut 60 and the spindle 62.As in the previously described embodiments, the two spring accumulators 32, 66 can be charged separately from one another or simultaneously. To tension the spring accumulator 32 of the switching drive 18, the valves 56, 100, 114 are energized and the shut-off valve 108 is de-energized. The capture valve 100 is thereby switched over into its switching position, in which the storage line 102 of the capture cylinder 84 is connected to the low-pressure line 92. In addition, the pressure medium connection between the connecting line 80 or the line 78 with the low-pressure line 92 is shut off via the check valve 100, and the pressure medium connection to the clamping chamber 72 is closed via the shut-off valve 114. When the clamping pump 40 is activated, pressure medium can then be conveyed into the pressure chamber 24 via the connecting line 80, the shut-off valve 108 in its basic position, the pressure line 42, the damping throttle 106 and the damping nonreturn valve 50, with the result that, as a function of the pressure applied via the clamping pump 40, the piston 36 is retracted and the spring accumulator 32 is tensioned accordingly.To tension the spring 66 of the control drive 8, the two valves 108 and 100 are energized, while the shut-off valve 114 is switched off, the switching position of the switching valve 56 can be selected as desired.When the clamping pump 40 is activated, the pressure medium is then conveyed via the check valve 52 and the open shut-off valve 114 into the clamping chamber 72, so that the piston 70 moves in and correspondingly clamps the spring 66. The supply of pressure medium to the clamping chamber 72 is interrupted when the desired prestress is reached. Subsequently, all valves are energized, so that the pressure medium is clamped in the respective pressure chambers 24, 72 and the spring accumulators 32, 66 are prestressed accordingly.For the simultaneous tensioning of these spring accumulators 32, 66, the two valves 108 and 114 are switched off, while the two other valves 56 and 100 are energized and thus shut off the pressure medium connection to the respective low-pressure accumulator 44 and 94. When the clamping pump 40 is activated via the pump motor, for example an asynchronous motor 46, pressure medium is then conveyed via the check valve 52 and the open shut-off valve 114 into the clamping chamber 72 and via the shut-off valve 108 and the pressure line 42 into the pressure chamber 24, so that both spring accumulators 32, 66 are simultaneously tensioned. After the desired prestress has been reached, the clamping pump 40 is switched off and the two valves 108, 114 are also energized, with the result that the pressure medium is clamped in the pressure chamber 24 or in the clamping chamber 72. The adjusting arrangement can then be controlled in the manner described above for setting the gas volume flow to the gas turbine 1.Disclosed are an actuating arrangement for actuating a control element, for example a valve controlling a process current or an actuator for adjusting a device, a switching unit suitable for such an actuating arrangement, and a valve arrangement having such an actuating arrangement. According to the invention, the adjusting arrangement has a regulating drive and a switching drive assigned to it, which both allow the control element to be reset to a predetermined basic position independently of one another in the event of a fault.List of reference characters1 Gas turbine 2 Actuating arrangement 4 Regulating valve 6 Switching valve 8 Regulating drive 10 Spindle drive 12 Emergency actuating device 16 Damping device 18 Switching drive 20 Spring accumulator 21 Gas line 22 Switching piston 24 Pressure chamber 26 Switching driver 28 Switching stop 30 Switching energy accumulator 32 Spring accumulator 34 Clamping cylinder 36 Piston 38 Piston rod 40 Clamping pump 42 Pressure line 44 LP switching hydraulic accumulator 46 Asynchronous motor 48 End position damping 50 Damping nonreturn valve 52 Nonreturn valve 54 Relief line 55 Suction line 56 Switching valve 57 Diaphragm 58 Driver 60 Spindle nut 62 Spindle 64 Spindle motor 65 Stop 66 Spring 68 Actuating cylinder 70 Actuating piston 72 Clamping chamber 74 Piston rod 76 Impact spring 78 Line 80 Connecting line 82 Connecting valve 84 Catching cylinder 86 Catching piston 88 Cylinder chamber 89 Catching piston rod 90 Annular chamber 92 Low-pressure line 94 Low-pressure accumulator 96 End position damping 98 channel 100 trap valve 102 storage line 104 damping orifice 106 damping orifice 108 shut-off valve 110 closing valve 112 nonreturn valve 114 shut-off valve 115 shut-off valve 116 shut-off valve 117 circulation valve 118 redundant clamping pump 119 asynchronous motor 120 redundancy line 122 circulation line

Claims

Actuating arrangement having a regulating drive (8) for actuating a control element, for example a valve (4) controlling a process current, or an actuator for adjusting a device, having an electric actuating drive for proportionally actuating the control element in an active direction, an emergency actuating device (12) for resetting in the event of a fault counter to the active direction being assigned to the latter, the emergency actuating device (12) having a prestressed energy store (66), the stored energy of which can be used for resetting, and having a switching drive (18) for actuating a switching element, for example a switching valve (6) or a switching actuator, which switching element is provided - in series with the control element and can be reset counter to the active direction in the event of a fault via a switching energy store (30) prestressed hydraulically counter to the active direction, wherein the control drive (8) and the switching drive (18) are hydraulically coupled, wherein the switching energy store (30) is a spring store (32) which is loaded in the restoring direction by means of a piston (36), wherein the piston (36) delimits a pressure chamber (24) which can be loaded with low pressure for unloading, having a pump assembly (40, 84) for loading the pressure chamber (24) with a clamping pressure, wherein the pump assembly (40, 84) is assigned a check valve (52) which prevents a flow of pressure medium towards the pump assembly (40, 84) in normal operation of the clamping assembly.Actuating arrangement according to Patent Claim 1, wherein the pressure chamber (24) can be connected via a pressure line (42) and a normally open switching valve (56) to an LP switching hydraulic accumulator (44), which, in its switching position, closes off the pressure medium connection to the LP switching hydraulic accumulator (44).Actuating arrangement according to one of the preceding claims, wherein the pump assembly is a clamping pump (40), the high-pressure connection of which can be connected to the pressure chamber (24) or a clamping chamber (72).Actuating arrangement according to Patent Claim 3, wherein the clamping pump (40) is assigned to the switching drive (18) and is connected by its low-pressure connection to the low-pressure switching hydraulic accumulator (44).Actuating arrangement according to Patent Claim 3 or 4, wherein the clamping pump (40) is provided both for charging the energy store (66) on the control drive side and also the switching-drive-side switching energy store (30).Actuating arrangement according to one of Patent Claims 3 to 5, wherein a redundant clamping pump (118) is connected in parallel with the clamping pump (40).Actuating arrangement according to one of Patent Claims 3 to 6, having a circulation line (122) via which the pressure connection of the clamping pump (40, 118) can be connected to low pressure.Actuating arrangement according to one of the preceding claims, having a capture cylinder (84) for damping the actuating movement of the control element in the end position range, which can be actuated as a clamping pump for charging the energy store (66) and the switching energy store (30).Actuating arrangement according to Patent Claim 8, wherein the pumping is effected by adjusting a capture piston (86) of the capture cylinder (84) by means of the electric actuating drive (10).Actuating arrangement according to Patent Claim 8 or 9, wherein the catching cylinder (84) is designed as a differential cylinder and both pressure spaces (24, 72) are connected to low pressure.Actuating arrangement according to one of the preceding patent claims, wherein the switching energy store (30) has an end position damping (48).Shift drive (18) for an adjusting arrangement according to one of the preceding patent claims, having a spring accumulator (32) which can be prestressed by means of a clamping cylinder (34), the piston of which, on the one hand, acts on the spring accumulator (32) and, on the other hand, delimits a pressure chamber (24) which can be acted on by a clamping pressure via a pump assembly (40, 84).Valve arrangement having a regulating valve (4) and a switching valve (6) which can be adjusted by means of an adjusting arrangement according to one of Patent Claims 1 to 11.

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