EP2638297B1 - Hydraulic or pneumatic drive for actuating a fitting comprising a control valve or selector valve - Google Patents

Description

The invention relates to a hydraulic or pneumatic (fluidic) drive, which is provided for the actuation of valves having a switching or control valve, and comprises a control cylinder and a safety circuit which is connected in a line to which a cylinder chamber of the actuating cylinder , Two in series with each other connected shut-off valves. The valve can be used, for example, in a power plant, in the chemical or petrochemical industry, in oil and gas production, etc. Fittings are for example auxiliary safety valves, quick-acting valves, quick-opening valves, control valves, quick-release flaps, pilot valves, self-medium controlled isolation valves in power plants, valves for mixing the same or different substances, etc.

From the DE-AS 2 025 836 is a hydraulic safety circuit for a double-acting hydraulic cylinder with two pressure chambers is known in which in the event of an emergency shutdown, the two pressure chambers are connected to each other via a plurality of parallel pilot operated poppet valves. The pilot control is supplied either via a check valve from the pressurized chamber of the hydraulic cylinder or via a check valve from an external pressure source. In this safety circuit, it can be tolerated if one of the parallel-connected poppet valves fails during the quick shutdown.

From the US 5,133,189 It is known to arrange in two for safety reasons parallel to each other extending fluid paths each two in series with each other safety valves. The two parallel fluid paths are provided for redundancy in the event of a quick shutdown of a steam valve. The series connection of two safety valves makes it possible to individually test them during operation for their functionality.

From the DE 10 2004 042 891 B3 a safety circuit is known in which four logic valves according to the basic principle of the latter US 5,133,189 are arranged. A pressure chamber of a working cylinder can be relieved in an emergency via two mutually parallel discharge lines. In each relief line two logic valves arranged in series are provided, one of which is an active logic valve and the other is a passive logic valve.

A disadvantage of such safety circuits is that each passive logic valve can only be tested together with the active logic valve of the parallel line. For this purpose, a connecting line with a throttle is provided between the two parallel lines.

In contrast, the invention is based on the object to provide a hydraulic or pneumatic (fluidic) drive for the actuation of valves with a switching or control valve having the features of the preamble of claim 1 and in which the safety-relevant function of the shut-off valves can be tested individually at any time without the safety circuit or the control or switching valve or the system must be taken out of service.

This object is achieved by a hydraulic or pneumatic drive or generally by a fluidic drive having the features of patent claim 1.

The fluidic drive according to the invention can be used in particular for actuating a regulating or switching valve of a valve, for example in a power plant. The drive has an actuating cylinder which has at least one cylinder chamber which is connected to a hydraulic or pneumatic line. In the line a safety circuit is provided which has two shut-off valves connected in series with each other. The two shut-off valves are a first 2/2-way cartridge valve (logic valve) and a second 2/2-way cartridge valve (logic valve), each with a main control piston through which the fluidic connection between two respective working ports of a cartridge valve is controllable. The two 2/2-way cartridge valves each have a pilot valve. The second 2/2 way cartridge valves are fluidly closer to the cylinder chamber than the first 2/2-way cartridge valve. At least this first 2/2-way cartridge valve is an active logic valve having an active in the opening direction surface, which is acted upon by the associated pilot valve, regardless of whether there is a pressure at one of the working ports, with a pressure.

In such a fluidic drive it is ensured that the two series-arranged 2/2-way cartridge valves can be tested successively and independently. One of the two built-in valves can be designed as a passive logic valve without active surface, since at one of its working connections from the actuating cylinder or from a source of external pressure is present, which opens the cartridge valve after relieving a spring chamber of the cartridge by the associated pilot valve. The with its working ports serially arranged for a cartridge valve other cartridge valve is an active logic valve. The pilot valves of the two 2/2-way cartridge valves are connected with their connected to a pressure medium source and a pressure medium sink ports parallel to each other, so they can independently control the respective main stage.

The active-logic valve with the area active in the opening direction is preferably the 2/2-way cartridge valve, at the working ports of which no pressure is present in normal operation. Thus, this cartridge valve can be switched to test over the active area - in particular - be opened. Preferably, both 2/2-way cartridge valves are active logic valves. This has the advantage that the cartridge valves open very quickly.

Another advantage can be seen in the fact that the valve block having the logic valves can also be interchanged with respect to the actuating cylinder with respect to the actuating cylinder to be connected to the actuating cylinder. Provided by selection valve arrangements in the form of, for example, two check valves or a so-called shuttle valve that the Pilot valves are supplied in each case from the pressurized cylinder chamber with pressure medium and connected to their tank port to the cylinder chamber with the lower pressure, so there is an additional security with regard to the assembly.

In a particularly preferred embodiment of the hydraulic drive according to the invention, the actuating cylinder is a synchronous cylinder with a second cylinder chamber. The two cylinder chambers can be connected to one another via the line and via the two 2/2-way cartridge valves. It can then be displaced from the pressurized cylinder chamber, the pressure medium in the other cylinder chamber, so that the valve under the influence of pressure conditions can reach her in a safe position.

In another particularly preferred embodiment, the actuating cylinder also has a second cylinder chamber and is therefore also double-acting. The actuating cylinder can also be a synchronous cylinder. A synchronous cylinder is a cylinder in which the two cylinder chambers are facing equally large effective piston surfaces. To the second cylinder chamber, a second hydraulic line is connected, in which a second safety circuit is provided. This is designed in accordance with the first safety circuit and accordingly has a third 2/2-way cartridge valve and a fourth 2/2-way cartridge valve connected in series therewith. These each include a main control piston, with which the fluidic connection between two respective working ports is controllable, and a pilot valve. At least one, preferably both 2/2-way cartridge valves of the second safety circuit, are active logic valves having an active in the opening direction surface, which is acted upon by the associated pilot valve independent of the working ports with a pressure. In this case, a test of the cartridge valves of a line is independent of the installation valves of the other line and regardless of whether a pressure is present at a working port of the third and / or fourth 2/2-way cartridge valve.

Preferably, the active logic valve with the active in the opening direction surface is the 2/2-way cartridge valve, at its working ports in normal operation no pressure is present. Thus, this cartridge valve can be switched to test over the active area - in particular - be opened.

In this case, in each case a branching line can be connected to a further 2/2-way cartridge valve to the first and to the second line between the two cartridge valves. These cartridge valves also each have a main control piston, with which the fluidic connection between two respective working ports is controllable, and they each have a pilot valve. With such a hydraulic drive, the actuating cylinder can be adjusted in emergency operation as needed in a first or in a second direction.

If the main spools are position monitored, the operation of the 2/2-way cartridge valves can be easily tested. Preferably, the closed position and the open position of a 2/2-way cartridge valve are monitored. If a position sensor is used for position monitoring, for example in the form of an analogue encoder, with which each position of a main control piston can be detected, for example stop strokes can be used to detect differently set opening strokes of a main control piston without a limit switch also having to be readjusted. Only one other signal from the position transmitter can be regarded as authoritative electronically.

Preferably, the pilot valves position monitoring valve body.

In both cases, the position monitoring can be carried out by means of limit switches.

In order to minimize the leakage of control oil, it is preferred if the main control pistons have seals. In the case of the active-logic valves, these seals can be arranged in particular between the spring chamber and the active surface.

Preferably, the pilot valves are 4/2 directional seat valves. About this, the spring chamber of the associated cartridge valve acted upon in the closing direction acting control pressure while the active surface to be relieved. In emergency mode can Relieved via the 4/2-way poppet valve (reversed) the spring chamber and the active surface are acted upon by acting in the opening direction control pressure. It is preferred if the first-mentioned fluidic connections take place at an energized switching position and the second-mentioned fluidic connections in a currentless basic position of the 4/2-way seat valve.

In a preferred development of the hydraulic drive according to the invention, all 2/2-way cartridge valves are active logic valves having an active in the opening direction surface, which is acted upon by the associated pilot valve independent of the working ports with a pressure. This allows each cartridge valve to be tested without pressure on any of its working ports. This increases the flexibility of the safety circuit and reduces the effects of a faulty assignment of the installation valves during assembly. Due to the pressurization of the additional effective in the opening direction open the active logic valves very fast.

In a preferred development, a position sensor is arranged on a piston or on a piston rod of the actuating cylinder.

In normal operation, the actuator cylinder is actuated independently of the 2/2-way cartridge valves via a proportional or black / white directional control valve. In addition, a seat valve (blocking valve) is provided as a safety valve, with which the actuating cylinder and thus the valve can be kept leak oil-free in a predetermined position. To move to a new position of the valve, the directional control valve and the blocking valve are actuated and the actuating cylinder, powered by a pressure connection and a tank connection, moved. In a test of the 2/2-way cartridge valves can now in particular the blocking valve, but also the directional control valve, ie the actual control valves de-energized. Now, if the 2/2-way cartridge valves actuated, in particular repeatedly actuated, this leads due to the consumption of control oil to a loss of oil in the pressurized cylinder chamber and thus to a reduction in compression of the actuating cylinder and ultimately to a change in the position of the valve, if you make sure that the control oil is removed from the cylinder chamber. Even small changes will be detected by the position sensor on the actuating cylinder. By means of this detection of a change in position and its return to an electronic control, the process is detected. The change to the valve stem is clear evidence that the valve, but also the entire oil path work properly. Since the inspection also takes into account the mechanical dimensions and functions of all elements (valves, limit switches, valve position sender, initiated stroke, latency times), this system not only checks the function itself, but also detects changes that creep over a longer time Period could result (condition monitoring). By monitoring the proportional valve or the black / white directional control valve and the blocking element, the actual work elements are included in the review.

Once the check has been completed, the control path for the proportional valve or the black / white directional control valve is transferred back to the higher-level control. The verification of the valve function and all elements and signals involved is fully documented and archived.

A real movement on the actuating cylinder may only take place in the per thousand range, based on the total possible working stroke. A change of the valve spindle triggers no real movement at the valve seat of the valve, when the movement takes place within the Hook's straight line of the preloaded valve spindle.

If several safety blocks are arranged parallel to one another, then the safety blocks remain in function when checking a safety block in order to ensure safety.

A first variant of the safety circuit according to the invention has a control cylinder, via which a main valve in an emergency (but possibly not only in an emergency) can be relieved hydraulically or pneumatically, wherein - in particular for what - the actuating cylinder has a first cylinder chamber and a second cylinder chamber which are connectable to each other via a working line. In the Working line a first and a second series-connected shut-off valve are provided. The actuating cylinder may be, for example, a differential or synchronous cylinder.

A second variant of the safety circuit according to the invention has a control cylinder, via which a main valve in an emergency (-aber possibly not only in an emergency) can be actuated hydraulically or pneumatically, wherein the actuating cylinder has a first cylinder chamber, in particular via a first pressure medium flow path via a first working line - can be supplied with pressure medium. In the first pressure medium flow path - in particular in the first working line - a first and a second series-connected shut-off valve are provided. The actuating cylinder may e.g. be a differential or synchronous cylinder with two cylinder chambers.

In both variants of the safety circuit according to the invention, one of the two shut-off valves can be tested while the other shut-off valve remains closed. Neither the valve nor the system needs to be taken out of service.

• Öffnen des ersten und des zweiten Absperrventils;
• Öffnen des Hauptventils.

A method for switching a safety circuit according to the invention according to one of the two variants in an emergency has the steps:

• Opening the first and second shut-off valves;
• Opening the main valve.

In a preferred development of the second variant of the actuating cylinder has a second cylinder chamber, which is relieved via a second working line. In this case, a first and a second series-connected shut-off valve are provided in the second working line.

In another preferred development of the second variant of the actuating cylinder has a second cylinder chamber, which is supplied via a second pressure medium flow path with pressure medium accordingly. In this case, the first and the second cylinder chamber via the respective pressure medium flow path alternatively - in particular to a tank - relieved. Also in the second pressure medium flow path a first and a second series-connected shut-off valve are provided. As a result, a choice of the adjustment of the actuating cylinder and thus the valve is given in case of emergency.

• Öffnen des jeweiligen ersten und des jeweiligen zweiten Absperrventils der beiden Arbeitsleitungen; und
• Öffnen des Hauptventils.

A method for switching this training in an emergency has the steps:

• Opening the respective first and the respective second shut-off valve of the two working lines; and
• Opening the main valve.

There may be a total of six shut-off valves, two of which are working shut-off valves, which are directly connected to the two cylinder chambers and two of which are P shut-off valves, both directly connected to a pressure port of the safety circuit, and two of which Shut-off valves are both directly connected to a tank connection of the safety circuit.

• Öffnen der beiden Arbeits-Absperrventile und eines der beiden P-Absperrventile und eines der beiden T-Absperrventile; und
• Öffnen des Hauptventils.

A method for switching this training in an emergency has the steps:

• Opening the two working shut-off valves and one of the two P-stop valves and one of the two T-stop valves; and
• Opening the main valve.

It is preferred that the series-connected shut-off valves are respectively formed by logic valves or 2/2-way poppet valves having a valve body having a closing direction effective closing surface and an effective in the opening direction annular surface. The closing surface and the annular surface are both alternatively - in particular to the tank - relieved or acted upon with pressure medium.

It is further preferred if the logic valves or the 2/2-way poppet valves in each case by a 4/2-way valve - are piloted - especially in the seat design.

The currentless switching to the emergency operation of the safety circuit, so the opening of the main valve can be done when the 4/2-way valve a valve body has, in its biased by a spring emergency position in the closing direction effective closing surface - in particular to the tank - is relieved, while in the opening direction effective annular surface is acted upon with pressure medium.

It is preferred if the series-connected shut-off valves and / or the pilot-controlling 4/2-way valves-in particular with sensors attached to the valve bodies-are electronically monitored.

In a particularly preferred application of the safety circuit according to the invention, the main valve is a shut-off valve or a safety valve of a system under vapor pressure.

• Öffnen des ersten Absperrventils bei geschlossenem zweiten Absperrventil;
• Öffnen des zweiten Absperrventils bei geschlossenem ersten Absperrventil. Damit kann jedes Absperrventil gangbar gehalten werden, ohne dass dabei der Stellzylinder und damit des Hauptventil verstellt also geöffnet werden muss.

The method according to the invention for maintaining or maintaining such a safety circuit has the following steps:

• Opening the first shut-off valve with the second shut-off valve closed;
• Opening the second shut-off valve with the first shut-off valve closed. Thus, each shut-off valve can be kept practicable, without causing the actuating cylinder and thus the main valve adjusted so it must be opened.

• Figur 1 einen Schaltplan einer Ventilanordnung eines hydraulischen Antriebs für eine Armatur, die ein Regel- oder Schaltventil aufweist, wobei an diesen Schaltplan die in den folgenden Figuren gezeigten Sicherheitsschaltungen angeschlossen sind;
• Figur 2 einen Schaltplan eines ersten Ausführungsbeispiels einer erfindungsgemäßen Sicherheitsschaltung;
• Figur 3 ein Aktivlogik-Ventil mit Vorsteuerventil gemäß dem ersten und den weiteren Ausführungsbeispielen;
• Figur 4 einen Schaltplan eines zweiten Ausführungsbeispiels der erfindungsgemäßen Sicherheitsschaltung;
• Figur 5 ein Sicherheitsventil bzw. Regelventil mit Differentialzylinder eines dritten Ausführungsbeispiels der erfindungsgemäßen Sicherheitsschaltung;
• Figur 6 ein Sicherheitsventil bzw. Regelventil mit Differenzialzylinder eines vierten Ausführungsbeispiels der erfindungsgemäßen Sicherheitsschaltung;
• Figur 7 einen Schaltplan eines fünften Ausführungsbeispiels der erfindungsgemäßen Sicherheitsschaltung; und
• Figur 8 einen Schaltplan eines sechsten Ausführungsbeispiels der erfindungsgemäßen Sicherheitsschaltung.

In the following, various embodiments of the invention will be described in detail with reference to FIGS. Show it:

• FIG. 1 a circuit diagram of a valve assembly of a hydraulic actuator for a valve having a control or switching valve, to which circuit diagram, the safety circuits shown in the following figures are connected;
• FIG. 2 a circuit diagram of a first embodiment of a safety circuit according to the invention;
• FIG. 3 an active logic valve with pilot valve according to the first and further embodiments;
• FIG. 4 a circuit diagram of a second embodiment of the safety circuit according to the invention;
• FIG. 5 a safety valve or control valve with differential cylinder of a third embodiment of the safety circuit according to the invention;
• FIG. 6 a safety valve or control valve with differential cylinder of a fourth embodiment of the safety circuit according to the invention;
• FIG. 7 a circuit diagram of a fifth embodiment of the safety circuit according to the invention; and
• FIG. 8 a circuit diagram of a sixth embodiment of the safety circuit according to the invention.

FIG. 1 shows a circuit diagram of a valve assembly of a hydraulic drive, at its designated A1 and B1 ports each directly a working chamber 4; 204 and 6, respectively; 206 of one (in the Figures 2 and 4 to 8 shown) double-acting actuator cylinder 2; 202 are connected. The adjusting cylinder 2; 202 serve to set a respective safety valve or control valve 1; 101; 401 of a fitting. Such a control valve 1; 101; 401 is, for example, a steam valve that can assume intermediate positions in normal operation in order to control the steam flow. The valve may also be a switching valve, which is closed or open in normal operation and should take in certain situations in its second position. Apart from steam, however, it is also possible to control the flow of another medium, which is transported in the same way or changed in its parameters (for example by mixing).

To adjust the control valve 1; 101; 401 in normal operation supplies the in FIG. 1 shown valve assembly of the hydraulic drive one of the ports A1, B1 with a pressurized fluid (oil, air, gas or gas mixture), which is available at a pump port P, while connecting the other of the two ports A1, B1 with a tank port T. The following components of the in FIG. 1 between the ports P and T on the one hand and the terminals A1 and B1 on the other hand, a proportional (continuously) adjustable 4/3 way valve 26 is arranged, via which the pressurization of the terminals A1, B1 and thus the positioning of the control valve. 1 ; 101; 401 takes place. In this case, the proportional valve 26 is connected via a pump line 28 to the pump port P and via a tank line 30 to the tank port T. The position of a valve spool of the proportional valve 26 can be detected with a displacement sensor 31.

An output of the proportional valve 26 is connected via a working line 32 to the port A1, while a second port of the proportional valve 26 is connected via a second working line 34 to the port B1.

In the two working lines 32, 34, a seat valve 36 is arranged, via which the two working lines 32, 34 can be shut off. The seat valve 36 serves to the adjusting cylinder 2; 202 in case of failure of the electrical system or a safety check in any position of the control valve 1; 101; 401 leak-free to keep in a predetermined position. To move to a new position, serving as the main directional valve proportional valve 26 and serving as a safety blocking element seat valve 36 are actuated and the actuating cylinder 2; 202 proceed. Alternatively, the control of the actuating cylinder via an in FIG. 1 shown switching valve done.

FIG. 2 shows a circuit diagram of a first embodiment of a safety circuit according to the invention. It has a safety valve or control valve 1, which is in an emergency to relieve a (not shown) system that is under vapor pressure. The safety valve or control valve 1 has a valve body, which is held in a normal operation of the system against the vapor pressure at a valve seat and in an emergency in the (in FIG. 2 ) is lifted off position shown. The pressure of the steam is supportive. For the actuation of the control valve 1, a synchronous cylinder 2 with the two in the free cross-section the same size cylinder chambers 4 and 6 is present, wherein by supplying pressurized fluid into the cylinder chamber 6 with simultaneous displacement of pressurized fluid from the Cylinder chamber 4, the valve 1 is actuated in the closing direction and by allowing an outflow of pressurized fluid from the cylinder chamber 6 in the opening direction. The pressure in the cylinder chamber 6 results from the pressure in the cylinder chamber 4 and the force exerted by the steam in the opening direction of the valve 1 on this. While maintaining a pressure above this pressure in the cylinder chamber 6, the valve 1 can also be kept closed. For fast complete opening of the valve 1 cylinder chambers 4, 6 of the synchronous cylinder 2 can be connected via a working line, which consists of the working line sections 8a, 8b, 8c, 8d, 8e and 8f.

On a piston rod of the actuating cylinder 2, a position sensor 21 is arranged.

Between the two working line sections 8c and 8d, a first logic valve 12 is provided, while between the two working line sections 8d and 8e, a second logic valve 14 is provided. The two according to the invention in series logic valves 12, 14 are 2/2-way poppet valves and in FIG. 2 shown in a normal or basic position. In this case, both logic valves 12, 14 block the working line 8a-f, whereby the safety valve or control valve 1 alone via the valve assembly FIG. 1 is controllable. For switching over the two logic valves 12, 14 between normal operation and emergency operation, a first 4/2-way valve 16 and a second 4/2-way valve 18 serve as pilot control. The two logic valves 12, 14 and the two 4/2 Directional valves 16, 18 are arranged together in and on a control plate 20 having a pump port P and a tank port T.

The two 4/2-way valves 16, 18 are shown in their biased by a spring basic or emergency position. As a result, a respective closing surface 22, 24 which is effective in the closing direction of the valve body or main control piston of the logic valves 12, 14 is connected to the tank connection T via a relief line and thus relieved of pressure. Alternatively, the discharge, in particular if no tank connection is present or a tank connection is present but not used and is closed by a plug, via a check valve 21 a also to the cylinder chamber 4 or via a check valve 21 b to the cylinder chamber 6 take place, depending on in which cylinder chamber the lower pressure prevails. According to the embodiment FIG. 2 That would be the cylinder chamber 4. The respectively effective in the opening direction annular surfaces A4 of the logic valves 12, 14 are alternatively from a pump port P forth via a first check valve 23a or from the cylinder chamber 6 forth via a second check valve 23b or from the cylinder chamber 4 ago a third check valve 23c is pressurized. Thus, the valve body or main control piston of the two logic valves 12, 14 are lifted and the working line 8a-f released. Thus, the two cylinder chambers 4, 6 of the Gleichgangzylinders 2 are connected and the valve body of the safety valve or control valve 1 can in the in FIG. 2 shown position to be opened. In the other position of the pilot valves 16 and 18, the surfaces 22 are pressurized and the surfaces A4 relieved of pressure. In the figures, the logic valves are shown together with their pilot control in the rest position, which they occupy when there is no pressure in the system. The pilot valves 16 and 18 are thus - unlike the main stages - arranged in parallel with respect to their pressure and in terms of their tank connection and therefore can independently control their main stages.

The 4/2 way valves 16 and 18 may also be designed as 4/2 way seat valves. Then a leakage oil flow on the feedforward is not available or very small. Such 4/2 way seat valves are known for example from the data sheet RD 22058 / 07.09, page 5/14 Bosch Rexroth AG

As already indicated in a variant of the embodiment according to FIG. 2 also the tank connection T omitted or unused and clogged. Also, the pressure port P together with the check valve 25a may be omitted or clogged by dispensing with the provision of a check valve.

According to the embodiment FIG. 2 in each case the cylinder chamber 6 is pressurized. The pressure in the cylinder chamber 4 is lower than in the cylinder chamber 6. In principle, therefore, the check valves 25b and 25c and 21 a and 21 b would not be necessary. The respective pressure connection of the two pilot valves 16 and 18 could be connected directly only to the cylinder chamber 6 and the respective discharge connection directly to the cylinder chamber 4. This is also possible if as in FIG. 2 shown the tank port T and the pressure port P with check valve 25a available. In the cylinder chamber 4 would then prevail the same pressure as in the tank connection T. The pressure at the pressure port P would usually be lower than in the cylinder chamber 6, so that the check valve 25 a is closed. However, the check valves 21 a, 21 b, 25 b and 25 c are as out FIG. 2 shown present, so with respect to the connected to the cylinder chambers of the actuating cylinder 2 working connections of the control plate 20 is reversed arrangement of the control plate possible. Of course, pressure port P and tank port T would have to be properly connected to the other components of the system. The interchangeability increases flexibility and means increased installation and functional safety.

FIG. 3 shows the logic valve 12/14 with the pilot valve 16/18 according to FIG. 2 in an enlarged view and with additional details. This arrangement is also repeatedly installed in the following embodiments.

The logic valve 12/14 is an active logic valve 12/14, the main control piston acting in the opening direction and independently of the pressure at one of the terminals A and B pressurizable annular surface or active area A4 and the closing direction in the effective closing surface 22 / 24 has. At a collar arranged therebetween of the main control piston, a seal 38 is arranged to delimit the two adjacent spaces in which there are different pressures both in normal operation and in emergency operation.

The active area A4 of the logic valve 12 is also advantageous for the initiation of an emergency operation, since the opening stroke of the logic valve 12 starts at the same time with the opening stroke of the logic valve 14 and not only after a small opening stroke of the logic valve 14, the leads to a pressure build-up in the line section 8d.

The valve body of the pilot valve 16/18 and the main control piston of the active logic valve 12/14 are position monitored via a respective limit switch 40 and 42, respectively. The limit switch 40 detects whether the valve body of a pilot valve has reached its switched position. The limit switch 42 detects whether the piston of the main stage of a logic valve has reached its open end position. It can also in each case a second limit switch may be provided in order to detect both end positions in each case. In FIG. 3 is such a second limit switch 43 located, with which the closed position of the main stage of the logic valve is monitored. For the piston of the main stage, a continuous path detection can be provided so that different open end positions can be detected without mechanical adjustment of a limit switch.

FIG. 4 shows a circuit diagram of a second embodiment of a safety circuit according to the invention. About the synchronous cylinder 2, a valve body of a safety valve or control valve 101 is kept closed during normal operation, in this embodiment, the vapor pressure of the system (not shown) acts in the closing direction supportive. According to the embodiment according to FIG. 2 Thus, the flow direction of the steam through the valve is reversed.

The first cylinder chamber 4 of the synchronizing cylinder 2 can be connected via a first working line to the pressure port P of a control plate 120. In this case, the first working line is divided into sections 108a, 108b, 108c, 108d, 108e and 108f. Between the two sections 108e and 108d, a first logic valve 12 is arranged, while a second logic valve 14 is arranged between the two sections 108d and 108c.

The second cylinder chamber 6 of the Gleichgangzylinders 2 is connected via a second working line to the tank port T of the control plate 120. In this case, the second working line is divided into sections 110a, 110b, 110c, 110d, 110e and 110f. Between the two sections 110c and 110d, a third logic valve 15 is arranged, while a fourth logic valve 13 is arranged between the two sections 110d and 110e. All logic valves are active logic with an in FIG. 3 with A4 designated annular surface on the piston, which acts on pressure in the opening direction.

The logic valve 12 is controlled by a 4/2 way valve 16, the logic valve 14 is controlled by a 4/2 way valve 18, the logic valve 15 is controlled by a 4/2 way valve 19 and the logic valve 13 is piloted by a 4/2 way valve 17. The logic valves 12, 13, 14 and 15 and the 4/2-way valves 16, 17, 18 and 19 are the same as those in the first embodiment FIG. 2 existing logic valves and pilot valves and operate in the same way.

The logic valves 12 to 15 are shown in their closed position, it being understood that the electromagnets of the pilot valves 16 to 19 are energized and the pilot valves different from those in the FIG. 4 shown occupy their switched position in which the surfaces 22/24 (see FIG. 3 ) and the areas A4 / (see FIG. 3 ) are relieved of pressure. The fitting 101 takes the in FIG. 4 shown closed normal position. In emergency operation of the safety circuit, the four 4/2-way valves 16 to 19 after switching off the electromagnets by a respective spring in their in FIG. 4 shown basic or emergency position, whereby the valve body of the logic valves are lifted from their valve seats. Thereby, the first working line 108a-f and the second working line 110a-f are released. Thus, a pressure medium supply from the pressure accumulator 126 held at a certain pressure can flow via the pressure port P and via the first working line 108a-f into the first cylinder chamber 4, while a corresponding amount of pressure medium from the second cylinder chamber 6 via the second working line 110a-f and the tank port T flows to a tank, not shown. The piston and the piston rod of the adjusting cylinder 2 are moved in the sense of an enlargement of the cylinder chamber 4 and a reduction of the cylinder chamber 6 and lift the valve body of the safety valve or regulating valve 101 from its valve seat. Steam can escape from the steam-carrying system, not shown, according to the two arrows.

The first working line 108a-f is thus used in emergency mode as a supply line, while the second working line 110a-f serves as a return line. The first cylinder chamber 4 can be supplied in emergency operation via the first working line 108a-f from the pressure accumulator 126, which is charged during normal operation of the safety circuit to a certain pressure.

It is also conceivable that the fitting 101 made FIG. 4 in normal operation is in an open position, via a control to FIG. 1 is adjustable. in the

Emergency operation then the valve must be opened quickly completely. This is done by means of the logic valves 12 to 15. In this case, the rapid movement of the valve is provided in the emergency position provided even if the proportional valve 26 or the switching valve off FIG. 1 receives a signal that counteracts the placement of the valve in the emergency position. Because the flow cross sections of the logic valves are compared to the flow cross sections in the valves 25 so large that the logic valves override the valve 26.

FIG. 5 shows a section of a third embodiment of the safety circuit according to the invention. In this case, the safety valve or control valve 1 as in the first embodiment (see FIG. 2 ) is shown to be actuated against the vapor pressure in the direction to close and to be opened in emergency operation with vapor assist.

The purpose of a differential cylinder 202, the first cylinder chamber 204 is a piston rod side cylinder space, while a second cylinder chamber 206 is a bottom-side cylinder chamber.

The piston of the differential cylinder 202 is operatively connected to a position sensor 21 which detects each position of the piston.

Incidentally, the third embodiment of the safety circuit according to the invention with respect to the lines, the control plate with the valves and the pressure accumulator according to the second embodiment according to FIG. 4 , Accordingly, the first cylinder clamp 204 is connected to the pressure port P of the control plate 120 via the first working line 108a-f, while the second cylinder chamber 206 is connected to the tank port T of the control plate 120 via the second working line 110a-f. Of these two working lines, only a part of the first section 108a or 110a is shown in each case.

FIG. 6 shows the safety valve or regulating valve 101 with a flow according to the second embodiment (see. FIG. 4 ), whereby to its adjustment the differential cylinder 202 according to the third embodiment (see. FIG. 5 ) is used.

Incidentally, the fourth embodiment of the safety circuit according to the invention with respect to the lines, the control plate with the valves and the pressure accumulator according to the second embodiment according to FIG. 4 , Accordingly, the first cylinder chamber 204 is connected to the pressure port P of the control plate 120 via the first working line 108a-f, while the second cylinder chamber 206 is connected to the tank port T of the control plate 120 via the second working line 110a-f. Of these two working lines, only a part of the first section 108a or 110a is shown in each case.

According to FIG. 6 the safety valve or control valve 1 as in the second embodiment (see FIG. 4 ) flows through the steam so that it is operated against the vapor pressure in the direction of opening and closed in emergency operation with steam support.

In emergency operation, the first cylinder chamber 204 via the first working line 108a-f pressure medium -. B. from the pressure accumulator 126 -. This opens the safety valve or control valve 101 against the vapor pressure. From the second cylinder chamber 206 pressure medium is displaced.

FIG. 7 shows a circuit diagram of a fifth embodiment of the safety circuit according to the invention. A valve body of a safety valve or control valve 401 is shown according to a normal operation in its normal position in which it shuts off steam of a system not shown in detail. Starting from the position shown, the valve body in an emergency operation via the synchronous cylinder 2 by pressurizing a first cylinder chamber 4 - FIG. 7 viewed - are moved to the right according to the arrow above the synchronous cylinder. The purpose of a first working line of a control plate 420, which can connect a pressure port P with the first cylinder chamber 4 via two logic valves 12, 14 connected in series according to the invention. The thereby displaced from the second cylinder chamber 6 pressure fluid flows through a second working line to a tank port T of Control plate 420, wherein two erfindungemäß to each other in series logic valves 15, 13 are arranged in the second working line. In this case, the first working line is composed of the line sections 408a, 408b, 408c, 408d, 408e, 408f, 408g, 408h and 408i. The second working line is composed of the line sections 410a, 410b, 410c, 410d, 410e, 410f and 410g. In the first working line, the first logic valve 12 is arranged between the line sections 408e and 408f, while the second logic valve 14 is arranged between the line sections 408b and 408c. In the second working line between the line sections 410e and 410f, the first logic valve 13 is arranged, while between the line sections 410b and 410c, the second logic valve 15 is arranged. In addition, the control plate 420 has two further logic valves 512, 513, which in the fifth embodiment according to FIG. 7 not needed. All logic valves are active logic.

The two first logic valves 12, 13 and the two second logic valves 14, 15 and the two logic valves 512, 513, which are not required in the fifth exemplary embodiment, are piloted in the manner known from the exemplary embodiments 1 and 2.

FIG. 8 shows a circuit diagram of a sixth embodiment of the safety circuit according to the invention. With respect to the components, ie lines and valves, the arrangement of the fifth embodiment is according to FIG. 7 used. Regarding the function of the valve body of the safety valve or control valve 401 in emergency operation from the in FIG. 8 shown normal position not as in the embodiment according to FIG. 7 from left to right, but be adjusted according to the arrow above the synchronizing cylinder 2 from right to left. For this purpose, the second cylinder chamber 6 of the Gleichgangzylinders 2 via a - modified compared to the fifth embodiment, second working line to the pressure port P of the control plate 420, while the first cylinder chamber 4 of the Gleichgangzylinders 2 via a relative to the fifth embodiment modified, first working line to the tank port T. is relieved. The line sections 408a, 408b, 408c, 408d, 508e, 508f, 508g serve as the first working line, while the line sections 410a, 410b, 410c, 410d, 510e, 510f, 510g serve as the second working line.

According to the invention, two logic valves 512, 14 connected in series with one another are arranged in the first working line. In this case, the first logic valve 512 is arranged between the line sections 508e and 508f, while the second logic valve 14 is arranged between the line sections 408b and 408c. In the second working line, the first logic valve 513 is arranged between the line sections 510e and 510f, while the second thereto according to the invention connected in series logic valve 15 between the line sections 410b and 410c is arranged.

The two logic valves, according to the fifth embodiment FIG. 7 when the first two logic valves 12, 13 are used, are in the sixth embodiment according to FIG. 8 not used or used.

Thus, the control plate 420 according to the fifth and sixth embodiments with the total of six pilot operated logic valves 12, 13, 14, 15, 512, 513 for normal operation and the emergency operation of the safety valve or control valve 401 both when this is in emergency operation from the center position according to the fifth embodiment is to be adjusted in the one direction, as well as when the valve 401 is to be adjusted according to the sixth embodiment in the opposite direction. Depending on the desired direction of movement, of course, so that there is no short circuit between the pressure port P and the tank port T of the control plate 420, one of the two valves 12 and 512 or 13 and 513 remain closed in an emergency at least until the valve body of the fitting 401 has released a vapor stream.

Accordingly, the two logic 12 and 512 as well as the two logic 13 and 513 differ in terms of their feedforward. In normal operation, the pilot valves of the logic valves 12, 13, 14 and 15 are energized and then the logic valves 12 to 15 are closed. For de-energized pilot valves, the logic valves 12 to 15 are open. Now, if the same pilot valves for the logic valves 512 and 513 used, then these pilot valves in the operation after FIG. 7 remain energized in an emergency, while in an operation after FIG. 8 the pilot valves the logic valves 12 and 13 must remain energized in an emergency. Are the pilot valves of the logic valves 512 and 513, the rest position and the switching position with respect to the pilot valves 16 and 17 reversed, as shown in the FIGS. 7 and 8th is shown, the pilot valves of the logic valves 512 and 513 are not energized in normal operation. In case of an emergency, they are then functioning according to FIG. 7 to leave the pilot valve of the logic valves 512 and 513 de-energized and in the operation according to FIG. 8 the pilot valves of the logic valves 512 and 513 to energize and the pilot valves of the logic valves 12 and 13 are energized.

In all of the embodiments shown, for testing purposes or for holding the valve body or the main control piston of the logic valves 12, 13, 14, 15, 512, 513 of one of two series-connected logic valves 12, 13, 14, 15, 512 513, while the other logic valve 12, 13, 14, 15, 512, 513 remains closed. The system remains with the safety valve or regulating valve 1; 101; 401 in normal operation, while the safety of the safety circuit and the system (not shown) is still given. In this case, at least the logic valves, at their working ports in normal operation of one of the cylinder chambers or from a pressure port P of the control plate ago no pressure is applied as active logic valves with an independently acted upon by the working ports in the opening direction acting surface. Advantageously, all logic valves are active logic valves.

In addition to the embodiments shown, a plurality of control plates 20; 120; 420 for equal or different thresholds on the cylinder 2; 202 be provided and connected.

Notwithstanding the embodiments shown, the safety circuits according to the invention can also serve, in normal operation, the safety valve or control valve 1; 101; 401 open and close it in emergency mode.

For the main stage of a logic valve, there are two possible combinations with limit switches. Basically, you can distinguish between a closed reported position and an open reported position. The closed Position is always clearly defined in its position. An open position is clearly defined only for 100% opening travel. Both positions can be queried digitally by means of electrical NC or NO contacts or an NC / NO combination.

An open position may be located at an intermediate position between the closed position and the 100% open position by means of stroke limitation for the valve piston of the main stage. This intermediate position corresponds to a measured value greater than 0 and less than 100% as the voltage or current of an analog position encoder, which can be used to detect the intermediate positions without mechanical adjustment.

For checking the logic valves 12, 13, 14, 15, 512, 513 of all embodiments, two methods are available according to the invention: According to a first method, only one of the two logic valves 12, 13, 14, 15, 512, 513 open. This opening stroke of the main control piston is detected by the associated limit switch 42. In each case, the other logic valve 12, 13, 14, 15, 512, 513 connected in series remains closed. Possibly a cylinder chamber 4 or 6 taken control oil is by readjustment by the proportional valve 26 from FIG. 1 replaced.

According to a second method, first in FIG. 1 shown part of the drive ineffective. For this purpose, the proportional valve 26 and in particular the seat valve 36 are de-energized (see the in FIG. 1 positions shown). Thereupon, one of two logic valves arranged in series with one another is first opened by means of a programmable logic controller, not shown, by changing the energization of the electromagnet of the associated 4/2-way valve 16. Thereafter, this logic valve is closed again and the logic valve connected in series via the associated 4/2-way valve 18 is opened. With the help of the main stages of the logic valves associated position or position sensor while the proper or improper operation of the logic valves can be determined.

The alternating switching of two series-connected logic valves is optionally carried out several times in succession. Every time you shift something is consumed control oil. This control oil is at least in the embodiments of the Figures 2 and 4 taken from a cylinder space of the adjusting cylinder 2, provided that the pressure therein is higher than the pressure at the pressure port P of the control plate. According to the embodiment FIG. 2 each results in a low oil loss in the pressurized cylinder chamber 4 of the actuating cylinder 2 to the fact that the valve body of the control valve 1 is either relieved, but not opened or leaves its position slightly.

About the position sensor 21 on the actuating cylinder 2; 202 and the programmable logic controller, this process is detected. This serves as proof that both the entire oil path and the actuating cylinder 2; 202 and thus the control valve 1; 101 work.

Since this method and this review, the mechanical dimensions and functions of all elements (valves, limit switches, position sensor, initiated stroke, latency) are taken into account, this process not only the ability to function but it is also detected changes that creeping over could result in a longer period of time (condition monitoring). By monitoring the proportional valve 26 and the blocking element or seat valve 36 and the actual drive elements of the hydraulic drive according to the invention are included in the review. For this purpose, the hydraulic drive according to the invention is designed as a tuned and closed system.

If the check is completed (according to one of the variants described), the drive path for the proportional valve 26 is transferred again to the programmable logic controller. Thus takes over again in FIG. 1 shown part of the hydraulic drive, the pressure medium loading of the actuating cylinder 2; 202 via its directly with the cylinder chambers 4; 204 and 6, respectively; 206 connected ports A1 and B1. Optionally, the control deviations of the proportional valve 26 can be evaluated and compared with the position monitoring of the valve, so that the control function is monitored.

Disclosed are two variants of a safety circuit for hydraulically or pneumatically actuated valves via an actuating cylinder.

1. 1. Sicherheitsschaltung mit einem Stellzylinder 2, über den ein Hauptventil 1 in einem Notfall hydraulisch oder pneumatisch entlastbar ist, wobei der Stellzylinder 2 eine erste und eine zweite Zylinderkammer 4, 6 hat, die über eine Arbeitsleitung 8a-f verbindbar sind, dadurch gekennzeichnet, dass in der Arbeitsleitung 8 ein erstes und ein zweites in Serie geschaltetes Absperrventil 12, 14 vorgesehen sind.
   Gemäß der zweiten Variante kann der Stellzylinder in einem Notfall hydraulisch oder pneumatisch betätigt werden. Dazu hat der Stellzylinder zumindest eine erste Zylinderkammer, die in einem Notfall über einen ersten Druckmittelströmungspfad mit Druckfluid versorgt werden kann. In der ersten Arbeitsleitung sind ein erstes und ein zweites in Serie geschaltetes Absperrventil vorgesehen.
2. 2. Sicherheitsschaltung mit einem Stellzylinder 2; 202, über den ein Hauptventil 1; 101; 401 in einem Notfall hydraulisch oder pneumatisch betätigbar ist, wobei der Stellzylinder 2; 202 eine erste Zylinderkammer 4; 204 hat, der über einen ersten Druckmittelströmungspfad 108; 408; 508 mit Druckmittel versorgbar ist, dadurch gekennzeichnet, dass in den ersten Druckmittelströmungspfad 108; 408; 508 ein erstes und ein zweites in Serie geschaltetes Absperrventil 12, 14 vorgesehen sind.
   Aspekte der Erfindung sind:
3. 3. Sicherheitsschaltung nach Variante 2, wobei der Stellzylinder 2; 202 eine zweite Zylinderkammer 6; 206 hat, der über eine zweite Arbeitsleitung 110a-f entlastbar ist, und wobei in der zweiten Arbeitsleitung 110 ein erstes und ein zweites in Serie geschaltetes Absperrventil 12, 14 vorgesehen sind.
4. 4. Sicherheitsschaltung nach Variante 2, wobei der Stellzylinder eine zweite Zylinderkammer 6 hat, der über einen zweiten Druckmittelströmungspfad mit Druckmittel versorgbar ist, und wobei der erste und die zweite Zylinderkammer 4, 6 über den jeweiligen Druckmittelströmungspfad entlastbar sind, und wobei in dem zweiten Druckmittelströmungspfad ein erstes und ein zweites in Serie geschaltetes Absperrventil 12, 14 vorgesehen sind.
5. 5. Sicherheitsschaltung nach Aspekt 4, wobei sechs Absperrventile 12, 14 vorgesehen sind.
6. 6. Sicherheitsschaltung nach Variante 1 oder 2, wobei die Absperrventile von LogikVentilen 12, 14 oder von 2/2-Wege-Sitzventilen gebildet sind, die jeweils einen Ventilkörper haben, der eine in Schließrichtung wirksame Schließfläche 22, 24 und eine in Öffnungsrichtung wirksame Ringfläche hat, wobei die Schließfläche 22, 24 und die Ringfläche jeweils entlastbar oder mit Druckmittel beaufschlagbar sind.
7. 7. Sicherheitsschaltung nach Aspekt 6, wobei die Logik-Ventile 12, 14 oder die 2/2-Wege-Sitzventile jeweils von einem 4/2-Wegeventil 16, 18 vorgesteuert sind.
8. 8. Sicherheitsschaltung nach Aspekt 7, wobei das 4/2-Wegeventil 16, 18 einen Ventilkörper hat, in dessen durch eine Feder vorgespannten Notstellung die Schließfläche 22, 24 entlastet ist, während die Ringfläche mit Druckmittel beaufschlagt ist.
9. 9. Sicherheitsschaltung nach Aspekt 7, wobei die Absperrventile 12, 14 und/oder die 4/2-Wegeventile 16, 18 elektronisch überwacht sind.
10. 10. Sicherheitsschaltung nach Variante 1, wobei das Hauptventil ein Absperrventil oder ein Sicherheitsventil 1; 101; 401 eines unter Dampfdruck stehenden Systems ist.

In the first variant of the actuating cylinder can be relieved hydraulically or pneumatically in an emergency. For this purpose, the actuating cylinder has two cylinder chambers, which can be fluidly connected via a working line. In the working line a first and a second series-connected shut-off valve are provided.

1. 1. Safety circuit with a control cylinder 2, via which a main valve 1 is hydraulically or pneumatically relieved in an emergency, wherein the actuating cylinder 2 has a first and a second cylinder chamber 4, 6, which are connectable via a working line 8a-f, characterized a first and a second series-connected shut-off valve 12, 14 are provided in the working line 8.
   According to the second variant of the actuating cylinder can be actuated hydraulically or pneumatically in an emergency. For this purpose, the actuating cylinder has at least a first cylinder chamber, which can be supplied in an emergency via a first pressure medium flow path with pressurized fluid. In the first working line, a first and a second series-connected shut-off valve are provided.
2. 2. safety circuit with a control cylinder 2; 202, via which a main valve 1; 101; 401 is hydraulically or pneumatically actuated in an emergency, wherein the actuating cylinder 2; 202, a first cylinder chamber 4; 204, which via a first pressure medium flow path 108; 408; 508 can be supplied with pressure medium, characterized in that in the first pressure medium flow path 108; 408; 508 a first and a second series-connected shut-off valve 12, 14 are provided.
   Aspects of the invention are:
3. 3. Safety circuit according to variant 2, wherein the actuating cylinder 2; 202, a second cylinder chamber 6; 206, which is relieved via a second working line 110a-f, and wherein in the second working line 110, a first and a second series-connected shut-off valve 12, 14 are provided.
4. 4. Safety circuit according to variant 2, wherein the actuating cylinder has a second cylinder chamber 6 which is supplied via a second pressure medium flow path with pressure medium, and wherein the first and the second cylinder chamber 4, 6 are relieved via the respective pressure fluid flow path, and wherein in the second pressure fluid flow path a first and a second series-connected shut-off valve 12, 14 are provided.
5. 5. Safety circuit according to aspect 4, wherein six shut-off valves 12, 14 are provided.
6. 6. Safety circuit according to variant 1 or 2, wherein the shut-off valves are formed by logic valves 12, 14 or 2/2-way poppet valves, each having a valve body having a closing direction in the effective closing surface 22, 24 and an effective in the opening direction annular surface has, wherein the closing surface 22, 24 and the annular surface are each relieved or acted upon by pressure medium.
7. 7. Safety circuit according to aspect 6, wherein the logic valves 12, 14 or the 2/2-way seat valves are each piloted by a 4/2-way valve 16, 18.
8. 8. safety circuit according to aspect 7, wherein the 4/2-way valve 16, 18 has a valve body, in its biased by a spring emergency position, the closing surface 22, 24 is relieved, while the annular surface is acted upon by pressure medium.
9. 9. Safety circuit according to aspect 7, wherein the shut-off valves 12, 14 and / or the 4/2-way valves 16, 18 are electronically monitored.
10. 10. Safety circuit according to variant 1, wherein the main valve is a shut-off valve or a safety valve 1; 101; 401 is a vapor pressure system.

Claims (12)

1. Hydraulic or pneumatic drive, in particular for actuating a fitting with a regulating or switching valve (1; 101; 401) for example in a power plant or in a chemical or gas or oil delivery plant, having a control cylinder (2; 202) which has a cylinder chamber (4; 204) which is connected to a hydraulic or pneumatic line (8a-f; 108a-f; 408a-i), and having a safety circuit which has two shut-off valves connected in series with one another and arranged in the line, characterized in that the two shut-off valves are a first 2/2 directional cartridge valve (12) and a second 2/2 directional cartridge valve (14), which in fluidic terms is arranged closer to the cylinder chamber (4, 204) than the first 2/2 directional cartridge valve (12), with in each case one main control piston by means of which the fluidic connection between two respective working ports (A, B) can be controlled, wherein the two 2/2 directional cartridge valves (12, 14) comprise in each case one pilot-control valve (16, 18), and wherein at least the first 2/2 directional cartridge valve (12) has a surface (A4) which is active in an opening direction and which can be subjected to a pressure by means of the associated pilot-control valve (16) independently of the working ports (A, B).
2. Hydraulic or pneumatic drive according to Claim 1, wherein the pilot-control valve (16, 18) of the two 2/2 directional cartridge valves are arranged such that their ports connected to a pressure medium source and to a pressure medium sink are in parallel with one another.
3. Hydraulic or pneumatic drive according to Claim 1 or 2, wherein the control cylinder is a synchronous cylinder (2) with a first cylinder chamber (4) and with a second cylinder chamber (6), and wherein the line (8a-f) runs between the two cylinder chambers (4, 6).
4. Hydraulic or pneumatic drive according to Claim 1 or 2, wherein the control cylinder (2; 202) is of double-acting design and has a first cylinder chamber (4, 204), to which a first line (8a-f; 108a-f; 408a-i) and a first safety circuit with two 2/2 directional cartridge valves (12, 14) is connected, and a second cylinder chamber (6; 206), to which a second hydraulic or pneumatic line (110a-f; 410a-g) is connected, and wherein a second safety circuit is provided which has a third 2/2 directional cartridge valve (13) and, connected in series therewith, a fourth 2/2 directional cartridge valve (15) which, in fluidic terms, is arranged closer to the second cylinder (6, 206) than the third 2/2 directional cartridge valve (12), said third and fourth 2/2 directional cartridge valves both being arranged in the second line (110a-f; 410a-g) and having in each case one main control piston by means of which the fluidic connection between two respective working ports (A, B) can be controlled and comprising in each case one pilot-control valve (17, 19), wherein at least the third 2/2 directional cartridge valve (13) has a surface (A4) which is active in an opening direction and which can be subjected to a pressure by means of the associated pilot-control valve (17) independently of the working ports (A, B).
5. Hydraulic or pneumatic drive according to Claim 4, wherein the third 2/2 directional cartridge valve (13) and the fourth 2/2 directional cartridge valve (15) have in each case one surface (A4) which is active in an opening direction and which can be subjected to a pressure by means of the associated pilot-control valve (17) independently of the working ports (A, B).
6. Hydraulic or pneumatic drive according to Claim 4 or 5, wherein a first further 2/2 directional cartridge valve (512) is connected with a first working port to the fluidic connection between the first 2/2 directional cartridge valve (12) and the second 2/2 directional cartridge valve (14), and a second further 2/2 directional cartridge valve (513) is connected with a first working port to the connection between the third 2/2 directional cartridge valve (13) and the fourth 2/2 directional cartridge valve (15), and wherein the further 2/2 directional cartridge valves (512, 513) comprise in each case one main control piston, by means of which the fluidic connection between two respective working ports (A, B) can be controlled, and in each case one pilot-control valve and are connected with their second working port in each case to a different port (P, T) of the respective safety circuit than the first and third 2/2 directional cartridge valve (12, 13).
7. Hydraulic or pneumatic drive according to one of the preceding claims, wherein the main control piston of the 2/2 directional cartridge valves (12, 14, 13, 15, 512, 513) are subjected to position monitoring with regard to their open position and preferably also with regard to their closed position.
8. Hydraulic or pneumatic drive according to one of the preceding claims, wherein the pilot-control valves (16, 17, 18, 19) have movable valve bodies which are subjected to position monitoring.
9. Hydraulic or pneumatic drive according to one of the preceding claims, wherein the main control piston of the actively controllable 2/2 directional cartridge valves have seals (38) for sealing off a control chamber which acts in a closing direction with respect to the control chamber which acts, independently of the working ports, in an opening direction.
10. Hydraulic or pneumatic drive according to one of the preceding claims, wherein the pilot-control valves are 4/2 directional seat valves (16, 17, 18, 19).
11. Hydraulic or pneumatic drive according to one of the preceding claims, wherein all of the 2/2 directional cartridge valves (12, 13, 14, 15; 512, 513) have a surface (A4) which is active in an opening direction and which can be subjected to a pressure by means of the associated pilot-control valve (16, 17, 18, 19) independently of the working ports (A, B).
12. Hydraulic or pneumatic drive according to one of the preceding claims, wherein a position sensor (21) is arranged on a piston or on a piston rod of the control cylinder (2; 202).

Images