DE102013216790A1 - Switching fitting arrangement - Google Patents

Abstract

Disclosed is a Schaltarmaturanordnung with a switching drive for a control valve. A piston of the switching drive is acted upon via a switching spring with a biasing force in the closing direction of the switching device. In the opening direction of the piston can be acted upon via a pressure chamber with pressure medium. For pressure relief of the pressure chamber, a relief valve is provided. This is controlled via relief control valves. In addition, a bypass valve for pressure relief of the pressure chamber can be controlled via at least one relief control valve to perform a Teilhubprüfung.

Description

The invention relates to a Schaltarmaturanordnung according to the preamble of claim 1.

In the EP 1 413 810 A1 a generic Schaltarmaturanordnung a turbine valve for controlling a gas or steam supply to a turbine or for a process fitting for controlling a process stream in process technology is disclosed. Such Schaltarmaturanordnungen usually have an actuator, the subject of the EP 1 413 810 A1 designed as an electric spindle drive. In the case of a gas turbine, for example, by means of such an actuating arrangement, an opening cross-section of a fitting for adjusting a gas supply can be adjusted. In an emergency, such as a power failure or malfunction, the valve should be automatically reset to avoid damage to the system. For this purpose, in the known solution, the spindle drive associated with a toggle mechanism, which is locked in regular operation, that is, with sufficient power supply, in an extended position in which a biasing spring is stretched. In case of power failure, the locking mechanism releases the toggle, so that it is adjusted via the biasing spring from its extended position into its kinked position and according to this adjustment the valve in the predetermined basic position, usually the closed position, zurückverstellt.

In the DE 10 2009 021 668 A1 an arrangement is disclosed in which a valve via a variable speed drive and a fluidly arranged in series therewith switching device via a switching drive are operated. The variable speed drive is equipped with an emergency operation that closes the valve in the event of a power failure. In contrast to the above-described embodiment, this emergency operation is not performed by a toggle mechanism but by a spring which acts in the closing direction on the valve and which is hydraulically biased. In emergency operation, this biasing pressure is reduced to low pressure, so that the spring is heading for the control valve. Similarly, the switch valve is closed in case of power failure, so that damage to the turbine or a process plant is almost impossible. In this known solution, an electrically actuated valve fitting is arranged in a discharge path to the low pressure, which is biased in the direction of its open position by a spring and is electrically switchable to a position in which the discharge path is shut off. In the event of a power failure, this discharge path is then opened in accordance with this, so that the spring can relax.

An important requirement of such hydraulic Schaltarmaturanordnungen is that the emergency functionality of the actuator assembly during operation, can be checked largely without impairment. It should be determined whether the emergency operation is intact and can close the process fitting and / or the shift drive in case of power failure.

In the variable speed drive, this test is possible with relatively little effort, since the emergency function capability can be interrogated in the sense of a partial stroke test by suitable control of the variable speed drive. However, such Teilhubprüfung is not feasible with a conventional switch valve, as this is switched over the associated switching drive only between the open position and the closed position. Consequently, the check can not be carried out during operation of the turbine or process plant.

In the post-published publication DE 10 2012 009 732 another hydraulic Schaltarmaturanordnung is shown. This has at least two switching valves, each of which can be actuated by means of an actuator, preferably in the form of a hydraulic cylinder. To close the switching valves in each case an upstream and a downstream relief valve are connected in series in three parallel discharge paths. The relief valves are in this case brought to close the switch valves in a relief position. Between the output ports of the upstream and downstream relief valves, a bypass relief path with a nozzle is provided. Via a drive circuit, an upstream relief valve in a discharge path and a downstream relief valve in another discharge path in a test operation in a discharge position is adjusted. In this solution, a Teilhubprüfung the switch valve is realized by the Nebenentlastungspfad on the relief valves and chokes. However, the large number of relief valves disadvantageously leads to a high requirement for installation space and to a device-technically complex design of the switch-fitting arrangement.

In contrast, the present invention seeks to provide a compact and simple designed Schaltarmaturanordnung.

This object is achieved with a switch fitting arrangement according to the features of claim 1.

Other advantageous developments of the invention are the subject of further subclaims.

According to the invention, a switch fitting arrangement for switch fittings for controlling process fluid flows is provided. This has an actuator with an actuator element. The actuator is, for example, a switching drive which serves to actuate the switching device. About an energy storage, the actuator element may be biased toward a basic position in which the associated switching valve is closed. In the actuator, a pressure chamber may be provided, via which the actuator element opposite to the direction of the basic position with pressure medium of a high-pressure side, in particular by a hydraulic pump can be acted upon. Pressure medium can then be discharged from the pressure chamber via a relief path and a relief valve arranged in the relief path to a low-pressure side, in particular a suction side of the hydraulic machine. In addition to the discharge path, the pressure chamber is connected to three fluidically parallel secondary relief paths. In each of these a relief control valve is arranged. Via a respective relief control valve, the pressure chamber is then connected to the low-pressure side, in particular throttled, connectable. The relief valve is controllable by the relief control valves. The control is such that the relief valve is closed when at least two Nebenentlastungspfade are fluidly connected by the relief control valves with the high pressure side.

This solution has the advantage that one of the secondary relief paths can be used for the partial stroke test explained in the introduction, without the relief valve being influenced in this case. Thus, unlike the prior art, a sub-relief path is controlled by a relief control valve and not by a plurality of relief valves. This means that, for example, in contrast to the above-explained DE 2012 007 732 , no six relief valves or logic valves or 2/2-way cartridge valves are necessary, but it is only a relief valve needed. This leads to an extremely compact design of the switch valve assembly, which is further configured in terms of device technology simple. Thus, the Schaltarmaturanordnung a small space and a low weight. The Schaltarmaturanordnung can be designed cost-optimized by the invention in terms of their design.

In a further embodiment of the invention, the relief valve is connected to the relief control valves so that it can be brought into an open position when a connection of at least two Nebenentlastungspfaden via the relief control valves with the low pressure side.

Preferably, the relief valve is connected via shuttle valves to the relief control valves. As a result, the relief valve can be easily connected via the relief control valves with the high or low pressure side.

Advantageously, three shuttle valves are provided. These are preferably each output side connected to a control chamber of the relief valve to load this with pressure medium, whereby the relief valve can be closed or to release from this pressure medium, so that the relief valve can be opened. A respective shuttle valve is in each case connected to two different Nebenentlastungspfaden. A shuttle valve is on the input side connected to the first and second Nebenentlastungspfad, a shuttle valve on the input side to the second and third Nebenentlastungspfad and a shuttle valve on the input side to the first and third Nebenentlastungspfad. The arrangement of three shuttle valves advantageously three hydraulic control pressures can be interconnected.

The relief valve may be configured as a logic valve. It preferably has a radial outlet port connected to the low pressure side and an axial inlet port connected to the high pressure side. A valve body of the relief valve is then acted upon via the control chamber in the direction of a closed position with the pressure medium and with the spring force of a spring. In the closed position, a pressure medium connection between the pressure chamber of the actuator and the low pressure side is closed.

In a further embodiment of the invention, the secondary relief paths are connected to the discharge path or to a pressure fluid flow path between an input port of the relief valve and the pressure chamber of the actuator. Downstream of the branch, a check valve which opens in pressure medium flow direction to the relief control valves, in particular a non-return valve, is provided in a respective secondary relief path. Thus, pressure medium can flow from the high-pressure side to a respective relief control valve, but not from the relief control valve in the direction of the high-pressure side or the discharge path.

In a further embodiment of the invention, a respective shuttle valve is preferably connected on the input side in each case between the relief control valves assigned to it and the shut-off valves of the secondary relief paths assigned to it.

Preferably, the Nebenentlastungspfade are connected via a common flow control valve to the discharge path. The flow control valve is thus arranged in the pressure medium flow direction, starting from the discharge path, between it and the check valves or check valves of the secondary discharge paths. It is preferably used for setting a constant volume flow.

Advantageously, the relief control valves have a valve body, in particular a valve spool, which can be acted upon in the direction of a first switching position with a spring force of a valve spring and in the direction of a second switching position with a control force of an actuator. In the first switching position of the respective relief control valve associated Nebenentlastungspfad can be depressurized to the low pressure side and in the second switching position of the respective relief control valve associated Nebenentlastungspfad be connected to the high pressure side.

For limiting an outflow velocity of a pressure medium, which flows from the pressure chamber of the actuator via the relief valve, a throttle is provided. This is preferably arranged downstream of the relief valve.

In a further embodiment of the invention, a hydraulic machine, in particular a hydraulic pump, on the output side connected via a supply line to the input terminal of the relief valve. From the supply line then branches off a main line connected to the pressure chamber of the actuator. Furthermore, branches from the supply line from each connected to an input terminal of a respective relief control valve sub-line. On the input side, the hydraulic machine can be connected via a suction line to an outlet connection of the relief valve and to an outlet connection of a respective relief control valve. The suction line is preferably directly connected to the relief control valve and to the outlet port of the relief valve via the throttle.

Furthermore, a hydraulic accumulator can be connected to the suction line.

To limit the pressure, a pressure relief valve is preferably arranged between the supply line and the suction line, which can relieve pressure on the supply line to the suction line.

Furthermore, a pressure medium filter can be provided in the supply line.

In the supply line downstream of the hydraulic machine is preferably arranged after the branch of the sub-line and before the branch of the main line in the pressure fluid flow direction away from the hydraulic machine opening check valve, in particular a check valve.

In the sub-line can also be a in the pressure fluid flow direction away from the hydraulic machine opening check valve, in particular a check valve, can be arranged.

The switch assembly can be configured modular.

Thus, a safety block or valve block or a valve disc is provided, in which at least the relief valve, the relief control valves, the shuttle valves and the check valves of the relief paths are arranged. This has a low pressure connection and at least one high pressure connection for the high and low pressure side. The safety block thus has, regardless of its function and size to the other elements, such as actuator or hydraulic machine, always the same hydraulic interface, namely the low pressure port and at least one high pressure port. Preferably, a second high pressure port is provided on the safety block. Thus, a high-pressure connection for the supply line and a high-pressure connection for the sub-line can be used. One high pressure port is thus provided for the relief control valves and the other high pressure port for the relief valve and the secondary relief paths. In addition, the throttle and / or the flow control valve can be provided in the safety block.

Alternatively or in addition to the safety block, a cylinder unit or a cylinder block or a cylinder disk is provided. The actuator is then arranged in the cylinder unit. The cylinder unit in this case preferably has the same connections as the safety block and preferably additionally a high-pressure and low-pressure connection for the hydraulic machine. Furthermore, the pressure limiting valve and / or the hydraulic accumulator and / or the shutoff valves for the supply line and sub line and / or the pressure medium filter can be arranged in the cylinder block.

Through the safety block and / or through the cylinder block, the required components are simple and compact. Furthermore, a simple and identical interface design is possible both hydraulically and mechanically. In the cylinder unit are then preferably all basic hydraulic functions and elements shown. The safety block then preferably has, regardless of its function and size to the cylinder unit always the same hydraulic interface or the same hydraulic interfaces.

Alternatively or in addition to the safety block and / or cylinder block, a drive block or a drive pulley may be provided for the hydraulic machine. This then simply has a high and low pressure port to be connected to the cylinder view. Furthermore, it is conceivable to arrange a drive unit for the hydraulic machine in the drive block.

In the following, a preferred embodiment of the invention will be explained in more detail with reference to a drawing. This shows the Schaltarmaturanordnung in a hydraulic circuit diagram.

The single figure shows a switch assembly 1 for controlling process fluid flows. Beigteordnet such a switch fitting usually a control valve, with the steam flow rate of a steam turbine is adjustable. The switch fitting assembly 1 has an actuator or a switching drive 2 with which a switching fitting, not shown, can be actuated. Such a switching cylinder 4 is sufficiently known from the prior art, which is why in the following only the essentials for the invention is explained and reference is otherwise made, for example, to the above-described prior art.

In regular operation, for example, a steam turbine, is the switching drive 2 held in an open position. In the event of a power failure, the switching drive will become 2 assigned switching valve moved over this in a closed position, so that a steam supply is shut off. The switching drive 2 is as a switching cylinder 4 educated. He has a butt 6 , which has an energy storage in the form of a switching spring 8th is biased in extended position, in which the switching drive 2 associated switching device is shut off. One from the piston 6 limited annulus 10 is loaded with pressure medium such that the piston can be acted upon by a pressure which is sufficient to him against the force of the switching spring 8th retract, bringing the the switching drive 2 associated switching device is open In the event of a fault, such as a power failure, the annulus 10 connected to low pressure, so that the associated switching valve is adjusted by the force of the switching spring in its locked position.

The switching drive 2 is in a cylinder block 12 intended. For controlling the switching drive 2 is one with the cylinder block 12 connected security block 14 intended. As a pressure medium source for adjusting the switching drive 2 is a hydraulic machine 16 in a drive block 18 intended.

The hydraulic machine 16 is used as a hydraulic pump 16 used and is about a drive shaft 20 with a drive unit 22 connected. The drive unit 22 along with the drive shaft 20 is also in the drive block 18 arranged. The hydraulic pump 16 is the output side with a supply line 24 connected. On the input side is the hydraulic pump 16 with a suction line 26 connected. A section of the supply line 24 in the drive block 18 opens into a high-pressure connection HA of the drive block 18 , The cylinder block 12 also has a high pressure port HA which communicates with the high pressure port HA of the drive block 18 connected is. From the high pressure port HA of the cylinder block 12 from then extends another section of the supply line 24 , The supply line 24 thus extends the output side of the hydraulic pump 16 through the drive block 18 via the high-pressure connections HA into the cylinder block 12 , The same applies to the suction line 26 , This extends from the cylinder block 12 from via a low pressure port NA of the cylinder block 12 and a low pressure port NA of the drive block 18 to the hydraulic pump 16 , In the supply line 24 in the area of the cylinder block 12 is a pressure medium filter 28 arranged. Downstream of the pressure medium filter 28 branches a pressure relief valve 30 off, that with the suction line 26 connected is. The pressure relief valve 30 is thus between the supply line 24 and the suction line 26 in the cylinder block 12 intended.

In the cylinder block 12 branches from the supply line 24 a sub-line 32 off, in which a check valve 34 is arranged. This opens in a fluid flow direction away from the hydraulic pump 16 , The sub-line 32 then extends over a high pressure port HA of the cylinder block 12 and a high pressure port HA of the safety block 14 in the security block 14 , The sub-line 32 then serves to supply a control pressure means for one in the security block 14 provided relief valve 36 ,

Downstream at the branch of the sub-line 32 is in the supply line 24 a check valve 38 provided in a pressure fluid flow direction away from the hydraulic pump 16 opens. Downstream of the check valve 38 branches in the cylinder block 12 a main line 40 off, in the annulus 10 of the shift cylinder 4 empties. The annulus 10 gets off the piston 6 of the shift cylinder 4 from another annulus 42 separated. This is over a connecting line 44 with the suction line 26 connected.

In the cylinder block 12 is also a hydraulic accumulator 46 provided to the suction line 26 connected.

The supply line 24 extends to the branch of the main line 40 to a high pressure port HA of the cylinder block 12 via a high-pressure connection HA of the safety block 14 in these. In the security block 14 opens the supply line 24 then into an axial input port E of the relief valve 36 , This is designed as a logic valve and has in addition to the axial input terminal E on a radial output terminal A. A valve body 48 the relief valve 36 is about a control room 50 acted upon in the direction of its closed position with control pressure medium. In addition acts on this in the direction of its closed position of a spring force of a valve spring 52 , In the closed position of the valve body 48 is a pressure fluid connection between the input port E and the output port A of the relief valve 36 blocked. In contrast, in an open position of the valve body 48 the input terminal E connected to the output terminal A, whereby pressure means from the supply line 24 in a relief line 54 can flow. This is a throttle 56 intended. The relief line 54 then flows into the suction line 26 extending from the cylinder block 12 via a low pressure port NA of the cylinder block 12 on to a low-pressure connection NA of the safety block 14 extends into these. About the relief valve 36 is thus at an open position of the valve body 48 Pressure medium from the annulus 10 of the shift cylinder 4 throttled in the suction line 26 entlassbar. The relief valve 36 is thus intended as an emergency operation to the switch valve via the shift cylinder 4 close as soon as possible.

Over three relief control valves 58 . 60 and 62 is the relief valve 36 controlled. A respective relief control valve 58 to 62 is designed as a 3/2-way seat valve. A respective relief control valve 58 to 62 in this case has an input terminal E, with the sub-line 32 An output terminal A of a respective relief control valve is connected 58 to 62 is then via a low pressure line 64 to the suction line 26 in the security block 14 connected. Control connections S of the relief control valves 58 to 62 are then via shuttle valves 66 . 68 and 70 with the control room 50 the relief valve 36 connected. A valve body of a respective relief control valve 58 to 62 is via a valve spring 72 acted upon by a spring force in the direction of a basic position a. In this, the control terminal S is connected to the output terminal A and the input terminal E is shut off. The respective valve body of the relief control valves 58 to 62 is then about an actor 74 in a switching position b can be brought, in which the input terminal E is connected to the control terminal S and the output terminal A is shut off.

The shuttle valves 66 to 70 are via their output terminal A together with the control room 50 the relief valve 36 connected. The shuttle valves 66 to 70 are thus starting from the control room 50 arranged fluidically parallel to each other. A respective shuttle valve 66 to 70 is then with two different relief control valves 58 to 62 connected. The first shuttle valve 66 is here with its input terminal E1 to the control terminal S of the relief control valve 60 and with its input terminal E2 to the control terminal S of the relief control valve 62 connected. The second shuttle valve 68 is with its input terminal E2 also with the control terminal S of the relief control valve 60 connected and with its further input terminal E1 to the control terminal S of the relief control valve 58 connected. The third shuttle valve 70 in turn, with its input terminal E1 to the control terminal S of the relief control valve 58 and with its input terminal E2 to the control terminal S of the relief control valve 62 connected.

To the control room 50 the relief valve 36 with pressure medium via the hydraulic pump 16 So it is necessary that at least two relief control valves 58 to 62 are actuated, whereby their valve body is in the switching position b. Are two relief control valves 58 to 62 operated, then the unconfirmed relief control valve via the shuttle valves 66 to 70 from the control room 50 the relief valve 36 fluidically separated while the operated relief control valves with the control chamber 50 via the shuttle valves 66 to 70 Fludisch are connected. Are all relief control valves 58 to 62 operated, so are the shuttle valves 66 to 70 also all discharge control valves with the control room 50 connected. Is only a relief control valve 58 to 62 actuated, then its control port S and the control room 50 via the shuttle valves 66 to 70 and the other two relief control valves 60 and 62 to the low pressure line 64 relieved. In general, the relief valve 36 by operating all relief control valves 58 to 62 closed. For emergency operation of the switching drive 2 then it is only necessary, two of the three relief control valves 58 and 62 to the low pressure line 64 open to the control room 50 the relief valve 36 to relieve, bringing the relief valve 36 can be opened. The emergency operation can thus be performed even if one of the relief control valves 58 to 62 fails, which is a hydraulic "2-out-of-3 circuit" is formed.

For tensioning the switching spring 8th of the shift cylinder 4 are all relief control valves 58 to 62 operated and the hydraulic pump 16 is operated at its maximum speed, bringing the relief valve 36 closed is. Is the switching spring 8th strained, so the speed of the hydraulic pump 16 lowered to 0.

A functional capability of the switching drive 2 is checked by a partial lift test. There are three side relief paths for this 76 . 78 and 80 intended. These are upstream of the relief valve 36 via a common flow control valve 82 to the relief path forming supply line 24 connected. In a respective discharge path 76 to 80 is a pressure medium flow away from the supply line 4 opening check valve 84 . 86 and 88 arranged. A respective side relief path 76 . 78 and 80 is to a respective relief control valve 62 . 60 respectively 58 connected. The side relief path 76 is with the control port S of the relief control valve 62 and thus with the input port E2 of the shuttle valve 66 and the input port E2 of the shuttle valve 70 connected. The side relief path 78 is on the other hand with the control port S of the relief control valve 60 and the input port E1 of the shuttle valve 66 and the input port E2 of the shuttle valve 68 connected. With the control port S of the relief control valve 58 is then the side relief path 80 connected. Furthermore, the secondary relief path 80 with the input port E1 of the shuttle valve 68 and the input port E1 of the shuttle valve 70 connected.

Through the side relief paths 76 to 80 can with one of the relief control valves 58 to 62 a Teilhubprüfung the shift cylinder 4 be performed. For this purpose, the valve body of the relief control valves 58 to 62 placed in its switching position a, while the valve body of the other relief control valves 58 to 62 remain in their switching position b. This causes the relief valve 36 is still closed. In contrast, the Nebenentlastungspfad 76 to 80 that with the relief control valve 58 to 62 is connected, the valve body is in the switching position a, with the low pressure line 64 connected. The following explanations will show the relief control valve 58 used for Teilhubprüfung. The connection with the low pressure line 64 causes pressure fluid from the annulus 10 of the shift cylinder 4 via the flow control valve 82 , the side relief path 80 and the relief control valve 58 to the low pressure line 64 and thus to the suction line 26 is relieved. The discharge takes place in such a way that the piston, for example, a certain partial stroke due to the spring force of the switching spring 8th in the direction of the closed position of the shift cylinder 4 performs. This sub-stroke is detected by sensors, whereby the functionality of the shift cylinder 4 or switching drive 2 can be checked. After execution of the partial stroke of the piston 6 becomes the valve body of the relief control valve 58 moved into its switching position b, which no further pressure medium via the annulus 10 and the side relief path 80 can flow out. After pressing the relief control valve 58 is then via the hydraulic pump 16 Pressure medium in the annulus 10 promoted, whereby the piston is again shifted so that the switching spring 8th is fully stretched again.

Disclosed is a Schaltarmaturanordnung with a switching drive for a control valve. A piston of the switching drive is acted upon via a switching spring with a biasing force in the closing direction of the switching device. In the opening direction of the piston can be acted upon via a pressure chamber with pressure medium. For pressure relief of the pressure chamber, a relief valve is provided. This is controlled via relief control valves. In addition, a bypass valve for pressure relief of the pressure chamber can be controlled via at least one relief control valve to perform a Teilhubprüfung.

LIST OF REFERENCE NUMBERS

1

 Schaltamaturanordnung

2

 Actuator / switching drive

4

 switching cylinder

6

 piston

8th

 switching spring

10

 annulus

12

 cylinder block

14

 safety block

16

 hydromachine

18

 drive block

20

 drive shaft

22

 drive unit

24

 supply line

26

 suction

28

 Pressure fluid filter

30

 Pressure relief valve

32

 subline

34

 check valve

36

 relief valve

38

 check valve

40

 main

42

 annulus

44

 connecting line

46

 hydraulic accumulator

48

 valve body

50

 control room

52

 valve spring

54

 relief line

56

 throttle

58

 Relief control valve

60

 Relief control valve

62

 Relief control valve

64

 Low-pressure line

66

 shuttle valve

68

 shuttle valve

70

 shuttle valve

72

 valve spring

74

 actuator

76

 Besides relief path

78

 Besides relief path

80

 Besides relief path

82

 Flow control valve

HA

 High pressure port

N / A

 Low pressure port

E, E1, E2

 input port

A

 output port

S

 control connection

a

 switch position

b

 switch position

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1413810 A1 [0002, 0002]
• DE 102009021668 A1 [0003]
• DE 102012009732 [0006]
• DE 2012007732 [0011]

Claims (15)

Switching fitting arrangement with an actuator element ( 6 ) of an actor ( 2 ) for actuating a switching device, which via an energy store ( 8th ) is biased in the direction of a basic position in which the associated switching valve is closed, and a pressure chamber ( 10 ) limited, over which it against the direction of the basic position with pressure medium of a high-pressure side ( 24 ) is acted upon, and from the pressure medium via a discharge path ( 24 . 54 ) and a relief valve arranged therein ( 36 ) to a low pressure side ( 26 ) is relieved, with three relief control valves ( 58 . 60 . 62 ) for controlling the relief valve ( 36 ) provided in such a way with the relief valve ( 36 ) that this is connected via two of the relief control valves ( 58 . 60 . 62 ) is controllable, characterized in that via one of the relief control valves ( 58 . 60 . 62 ) with the pressure chamber ( 10 ) associated side relief path ( 84 . 86 . 88 ) with the low pressure side ( 26 ) is connectable. Switching fitting arrangement according to claim 1, wherein three mutually parallel auxiliary discharge paths ( 76 . 78 . 80 ) are provided, with a respective Nebenentlastungspfad ( 76 . 78 . 80 ) with a respective relief control valve ( 58 . 60 . 62 ) via which the respective side relief path ( 76 . 78 . 80 ) with the low pressure side ( 26 ) is connectable. Switching fitting arrangement according to claim 1 or 2, wherein the relief valve ( 36 ) via shuttle valves ( 66 . 68 , 70 ) with the relief control valves ( 58 . 60 . 62 ) connected is. Switching fitting assembly according to claim 3, wherein three shuttle valves ( 66 . 68 . 70 ) are provided, each on the output side with a control room ( 50 ) of the relief valve ( 36 ), and wherein a shuttle valve ( 66 ) input side with the first and second Nebenentlastungspfad ( 76 . 78 ), a shuttle valve ( 68 ) input side with the second and third Nebenentlastungspfad ( 78 . 80 ) and a shuttle valve ( 70 ) input side with the first and third Nebenentlastungspfad ( 76 . 80 ) connected is. Switching fitting arrangement according to one of the preceding claims, wherein the relief valve ( 36 ) is designed as a logic valve. A switch fitting assembly according to any one of claims 2 to 5, wherein a respective side relief path ( 76 . 78 . 80 ) to the discharge path ( 24 ) in each case via a pressure medium flow direction towards the respective relief control valve ( 58 . 60 , 62 ) opening check valve ( 84 . 86 . 88 ) are connected. Switching fitting assembly according to claim 6, wherein the shuttle valves ( 66 . 68 , 70 ) on the input side between the relief control valves ( 58 . 60 . 62 ) and the check valves ( 84 . 86 . 88 ) to the secondary relief routes ( 76 . 78 . 80 ) are connected. Switchgear assembly according to one of claims 2 to 7, wherein the auxiliary discharge paths ( 76 . 78 . 80 ) via a flow control valve ( 82 ) to the discharge path ( 24 ) are connected. Switching fitting arrangement according to one of the preceding claims, wherein on the valve body of a respective relief control valve ( 58 . 60 . 62 ) in the direction of a first switching position (a), in which the respective relief control valve ( 58 . 60 . 62 ) associated side relief path ( 76 . 78 . 80 ) with the low pressure side ( 26 ), with a spring force of a valve spring ( 72 ) is acted upon and in the direction of a second switching position (b), in which the respective relief control valve ( 58 . 60 . 62 ) associated discharge path ( 76 . 78 . 80 ) with the high pressure side ( 24 ), with a control force of an actuator ( 64 ) can be acted upon. Switching fitting arrangement according to one of the preceding claims, wherein the relief valve ( 36 ) via a throttle ( 56 ) with the low pressure side ( 26 ) connected is. Switching fitting arrangement according to one of the preceding claims, wherein a hydraulic machine ( 16 ) on the output side via a supply line ( 24 ) with an inlet connection (E) of the relief valve ( 36 ) and the pressure chamber ( 10 ) of the actuator ( 2 ), whereby from the supply line ( 24 ) one with an input port (E) of a respective relief control valve ( 58 . 60 . 62 ) associated sub-line ( 32 ) branches off. Switching fitting arrangement according to claim 11, wherein in the supply line ( 24 ) downstream of the hydraulic machine ( 16 ) after the diversion of the sub-line ( 32 ) in a fluid flow direction away from the hydraulic machine ( 16 ) opening check valve ( 38 ) and / or wherein in the sub-line ( 32 ) in the fluid flow direction away from the hydraulic machine ( 16 ) opening check valve ( 34 ) is located. Switching fitting arrangement according to one of the preceding claims, wherein a safety block ( 14 ) is provided, in which at least the relief valve ( 36 ) together with the shuttle valves ( 66 - 70 ), the secondary relief pathways ( 76 - 80 ) and the relief control valves ( 58 - 62 ), the security block ( 14 ) is connectable to the low pressure side via a low pressure port (NA) and to the high pressure side via a high pressure port (HA). Switching fitting arrangement according to claim 13, wherein in a cylinder block ( 12 ) at least the actuator ( 2 ), wherein the cylinder block ( 12 ) the same connections as the security block ( 14 ) and additionally a high and low pressure connection (HA, NA) for the hydraulic machine ( 16 ) having. Switching fitting arrangement according to claim 14, wherein in a drive block ( 18 ) at least the hydraulic machine ( 16 ), wherein the drive block ( 18 ) a high and low pressure port (HA, NA) for connection to the cylinder block ( 12 ) or security block ( 14 ) having.

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