EP0631056B2 - Actuator for a control valve - Google Patents

Description

TECHNICAL AREA

The invention relates to an actuator for a control valve according to the preamble of the claim 1.

STATE OF THE ART

An actuator for operating a control valve with which, for example, the steam supply to a Turbine of a power plant is regulated points one connected to the actuating rod of the control valve Main piston of a piston-cylinder arrangement on the one hand with spring force and on the other hand is pressurized with oil. When it wears off Pressure of the main piston acting in the opening direction Oil, the spring force securely closes the control valve, which stops the steam supply. This ensures that the turbine is not gets out of control once the pressure of the oil should fall off. The oil pressure in a drive volume, that acts on the main piston and over it the Control valve operated by an electro-hydraulic Converter generated. When the control valve moves in the opening direction, oil is pressurized into the Drive volume fed because of this movement comparatively slow, comparatively enough small cross sections for feeding the Oil. However, the control valve has a closing movement at a speed about ten times faster to take place. This requires a comparative rapid emptying of the drive volume, which however, due to the small cross-sections of the oil feed cannot be reached.

It also shows that as a result of the enlargement the turbine performance also the control valves and thus the actuators that operate them are larger or must be interpreted more strongly. A corresponding proportional enlargement of the actuators leads to arrangements with comparatively large Amounts of oil under pressure to operate them. With commercially available Valves can be used in such quantities It is difficult to control oil, and it also suffers the dynamics of the actuator also with increasing size.

An actuator according to the European patent application 0430 089 A1 known the preamble of the claim.

Should an existing actuator be related dynamically improved with retrofit work a completely new one has to be built Piston-cylinder arrangement used what a comparatively large effort. Often is also for that in the European patent application 0 430 089 Al proposed solution no space available, so other, more elaborate solutions must be taken.

PRESENTATION OF THE INVENTION

The invention seeks to remedy this. The invention as in the single Claim is characterized, solves the problem of an actuator for a control valve to create the dynamic with comparatively simple means Behavior can be improved and the secondary damage with great certainty avoids.

The advantages achieved by the invention are in essential to see that the actuator is comparatively easy and reliable to set up can.

This actuator for a control valve has one Control loop on which the actuator accordingly one from a higher-level plant control system sets the specified setpoint. He also has one main piston sliding in a master cylinder, with a controlled pressurized with oil Drive volume on one side of the main piston, and a plate valve upstream of the drive volume. It has proven to be particularly advantageous that the Plate valve with one connected to a drain device separate storage volume is provided. In this way, the plate valve can be placed anywhere in the area of the piston-cylinder arrangement of the Actuator are arranged.

Between the drive volume and the plate valve a connection line is provided, which through a connector in a spring chamber of the plate valve flows into.

It has proven to be particularly advantageous that the separate storage volume concentrically around the Spring space is arranged around. The pressurized Spring chamber and the sealing points of the plate valve are completely of low in this way Surround pressurized volumes. Should now in the event of a defect, oil under high pressure from the spring chamber escape, this escapes into said Volumes, so secondary damage with great certainty be avoided.

The invention, its further development and the achievable with it Benefits are shown below using the Drawing, which is only one possible way of execution represents, explained in more detail.

BRIEF DESCRIPTION OF THE DRAWING

Fig.1

eine Prinzipskizze eines erfindungsgemässen Stellantriebes,

Fig.1a

ein Detail des erfindungsgemässen Stellantriebes gemäss Fig.1,

Fig.2

eine erste Ausgestaltung eines Details eines Plattenventils,

Fig.3

eine zweite Ausgestaltung eines Details eines Plattenventils,

Fig.4

eine dritte Ausgestaltung eines Details eines Plattenventils, und

Fig. 5

eine vierte Ausgestaltung eines Details eines 20 Plattenventils.

Show it:

Fig. 1

a schematic diagram of an actuator according to the invention,

Fig.1a

1 shows a detail of the actuator according to the invention according to FIG. 1,

Fig. 2

a first embodiment of a detail of a plate valve,

Fig. 3

a second embodiment of a detail of a plate valve,

Fig. 4

a third embodiment of a detail of a plate valve, and

Fig. 5

a fourth embodiment of a detail of a 20 plate valve.

Elements with the same effect are included in all figures provided with the same reference numerals. For better clarity For this reason, visible edges have been removed in Fig.la 25 been left.

WAYS OF CARRYING OUT THE INVENTION

FIG. 1 shows an actuator 1, which has a 30 gel valve 2 operated, which by a Hot steam line 3 to a turbine, not shown flowing hot steam regulates. The control valve 2 is through a valve stem 4 with one in one Master cylinder 5 sliding main piston 6 connected. 35 Below the main piston 6 is an oil pressurized acted upon drive volume 7 arranged. Instead of the oil can also be another hydraulic fluid or a gaseous medium can be provided. An oil-filled buffer 40 is located above the main piston 6 volume 8 provided, in which also a spring 9 is arranged, which is the oil pressure in the drive volume 7 counteracts. One leads from the buffer volume 8 Line 52 to a drain device, not shown. On the main piston 6 there is a rod 10 45 on the spring side provided which the same with a distance measuring device 11 connects. The path measuring device 11 monitors the stroke of the main piston 6 and reports its Position continuously, as indicated by a line of action 40, to a position controller 33. The rod 10 and the valve stem 4 penetrate the master cylinder 5 opposite sides. The constructive execution of these pressure-tight penetrations is known and need not be described further here The path measuring device 11 can also be 55 rich outside of the master cylinder 5 directly on the Valve stem 4 are attached.

On the master cylinder 5 is in the front area Drive volume 7 connected to a connecting line 15 which has a comparatively large cross section and which has the drive volume 7 of Master cylinder 5 with a spatially separated from it arranged plate valve 17 connects. The Plate valve 17 is shown in more detail in Fig.la. The plate valve 17 has a housing 22, which on one side by a cover flange 22a is completed. This cover flange 22a surrounds an intermediate volume 24. A is in the cover flange 22a Drain connector 24a provided to which a line is connected the intermediate volume 24 with a Connected drain device for the oil, not shown. In this housing 22 is a connector 14 inserted pressure-tight. The plate valve 17 is on a connecting flange, not shown, of the connecting line 15 flanged that one end 14a of the Connection piece 14 pressure-tight with the connecting line 15 is connected. The tubular connector 14 has a cylindrical at the other end trained seal seat 14b. The plate valve 17 has one, for example with an aperture 70 provided, plate 18 on by a compression spring 19 against the sealing seat 14b and at the same time against a sealing part 23 embedded in the housing 22 is pressed. In the closed state it prevents Plate 18 in the exit of oil from the spring chamber 20 in a concentrically surrounding the connector 14 Volume 21. Volume 21 goes into the intermediate volume 24 about. Enclose these two volumes the spring chamber 20 and the sealing points of the plate valve 17 concentric. The one in the operating state shown spring chamber pressurized with oil 20 is against this by means of a spring chamber cover 20a Intermediate volume 24 completed. The plate 18 is designed so that jamming of the same is excluded is. The compression spring 19 is in one by one Bore 12 and an opening 13 pressurized with oil Spring chamber 20 arranged. The spring chamber 20 is about a thousand times the order of magnitude designed smaller than the drive volume 7, with to which he is in active connection. The spring chamber 20 stands also in operative connection with a via a line 47 Proportional directional control valve 25.

As a proportional directional control valve 25, for example the directly operated proportional directional valve with position control type KFDG 4V - 3/5, series 20, from the company Vickers Systems GmbH, D 6380 Bad Homburg v.d.H. be used. The proportional directional valve 25 has two actuating magnets 26, 27, which are not shown Return springs cooperate, and in In this case, three hydraulic connections 28, 29, 30 In Fig. 1, the proportional directional control valve 25 is in the so-called "Fail-safe" position shown. The proportional directional valve 25 has one with a slide of Valve connected stroke measurement 31, which the respective Position of the slide measures and, as by a line of action 32 indicated this information in a position controller 33 with an integrated power amplifier passes on. The actuating magnets 26, 27 receive as indicated by lines of action 34, 35, their Commands from this position controller 33 with integrated Power amplifier. Furthermore, the position controller 33 an input for feeding one like the Line of action 40 indicates from the path measuring device 11 supplied electrical signal. As a position controller 33 can, for example, be a valve specifically for the proportional control valve 25 matched power amplifiers EEA-PAM-533-A, series 20, from Vickers Systems GmbH, D 6380 Bad Homburg v.d.H. used become. This position controller 33 cooperates with a higher-level controller 36, such as a line of action 37 implies. The controller 36 has further inputs 38 on what information and commands from one higher-level plant control technology, which covers the entire Power plant controls, be fed.

Oil is fed in under pressure through a line 45, the necessary oil pressure is shown by a not shown Pump generated. The flow rate of the oil is in some special cases by a in the course the line 45 arranged aperture 46 limited to a maximum amount. As a rule, however Flow rate of the oil through a in the plate 18th of the plate valve 17 provided aperture 70 limited so that the aperture 46 can then be dispensed with. Line 45 leads to connection 28 of the proportional directional valve 25, which is not in the representation of FIG. 1 is connected to connection 29. The connection 29 is connected on the one hand to a line 47, which in turn is connected to the bore 12 in the Spring chamber 20 of the plate valve 17 leads, and on the other hand with a line 48 to a normally closed safety valve designed as a plate valve 49 leads. After the safety valve 49 leads a line 50 into the intermediate volume 24 of the plate valve 17. The last piece of line 50 is shown in Fig. 1a as the wall of the housing 22 penetrating bore shown A line 51 branches from the line 50 and establishes the connection with the connection 30 of the proportional directional valve 25. The lines 50 and 51 are designed as bores in the housing 22, this is possible because both the proportional directional valve 25 as well as the safety valve 49 directly and flanged to the housing 22 in a pressure-tight manner, so that a monolithic valve block is created. From An intermediate nozzle 24a leads into an intermediate volume 24 Line leading to a drain device, not shown. The oil passes on from this drain device by the pump mentioned back into line 45.

The safety valve 49 is designed as a plate valve with a cylinder 53, one from a safety oil circuit forth through a line 54 with oil under pressure acted volume 55, which by a valve plate 56 is limited and with a valve spring 57, which the oil pressure acting on the valve plate 56 counteracts. From the schematic representation of the Safety valve 49 does not show that the valve plate 56 is designed so that it jams is impossible. Line 54 normally leads through a directional valve 58 and connects this with the volume 55. The directional valve 58 is through a Electromagnet 59 actuated. A line of action 60 indicates the path of the trigger command for the electromagnet 59 on.

It is particularly advantageous that the Plate valve 17 in all systems regardless of Type of the respective master cylinder 5 are used can. The line 15 can usually be compared run briefly so that the oil-filled pipe volume accordingly the dynamic turns out small advantageously increased. However, it is also possible to add to the plate valve 17 one or more others Valves should be provided if this depends on the operational requirements forth, which are placed on the actuator 1, seems desirable. It is also possible that Proportional directional valve 25 by at least one electro-hydraulic Valve or by a combination to replace various electrohydraulic valves, the actuator or its dynamic behavior to adapt to the specified operating conditions. The actuator is therefore very versatile.

The interaction of the position controller 33 with integrated power amplifier and the regulator 36 as common electronic control arrangement of a Control loop is particularly advantageous because the Position controller 33 specifically on the proportional directional valve 25 is adjusted so that no additional adjustments and adjustments are necessary. However, it is this electronic control arrangement is quite possible composed of other elements or theirs Function in a higher-level plant control system if, for example, the protection concept of Power plant would require this. In the electronic Control arrangement are from the distance measuring device 11 and 31 originating from the stroke measurement Signals continuously along with at least one, specified by the higher-level plant control system Setpoint according to a given logic processed. Generated in the event of deviations from this setpoint this control arrangement correction signals which on the actuating magnets 26, 27 of the proportional directional valve 25 act and a corresponding reversal effect it.

2 is part of the plate 18 of the plate valve 17 schematically shown in section. The spring chamber side Surface 65 of plate 18 is arranged on the right; this also applies to the following figures. A breakthrough through the plate 18 has a cylindrical opening 66 on which is a conical extension connects. A ball 67 is supported by a spring 68, which against one connected to the plate 18 Bracket 69 supports, in this conical extension pressed and closes the opening 66. Through the opening 66 can put oil under pressure in the connector 14 and through this and further through the connecting line 15 flow into the drive volume 7 as soon as a pressure difference occurs that is large enough to achieve the Force of the spring 68 and that acting on the ball 67 To overcome oil pressure.

Fig. 3 is similar to Fig. 2, except that in this In the event of a breakthrough with the opening 66 through the plate 18 is designed such that oil from the drive volume 7 forth through the connecting line 15 and through the connector 14 can flow into the spring chamber 20. In addition, there is a rigid aperture 70, which allows oil to flow in both directions. Of the The cross section of the aperture 70 is considerably smaller here designed as that of the opening 66.

It is of course also possible, as shown in FIG. 4, only a rigid aperture 70 in the plate 18 as a breakthrough to insert and thereby limit the oil passage.

Fig. 5 shows a plate 18 with two valve arrangements similar to that shown in Fig. 2, but in each other opposite directions if appropriate Allow differential pressure to allow oil to pass through. The opening 66, which from the drive volume 7 in the spring chamber 20 leads has a much larger cross section on than the second opening 66.

1 to explain the mode of operation considered in more detail. Control valve 2 must be in operation can be closed comparatively quickly. The closing speed is normally in the range by 1 m / sec, however, as the opening speed are just speeds around 0.02 m / sec required. This speed information are guide values depending on the design of the power plant can also have significant deviations from these Statements occur. The actuator 1 can be compared little effort to the respective operating conditions should be adjusted 2 are moved in the opening direction, so through the position controller 33 the proportional directional valve 25 actuated, and it is controlled so that the diagram to the left of the position shown applies. The connections 28 and 29 are then connected through and oil under pressure flows from line 45 forth through the proportional directional control valve 25. By line 48 cannot flow oil during normal operation, since the safety valve 49 closes this line 48. The oil flows through line 47, the bore 12 and the opening 13 in the spring chamber 20 of the Plate valve 17 and from there through the breakthrough the plate 18, through the connector 14 and through the connecting line 15 into the drive volume 7. The oil pressure in the drive volume 7 moves the Main piston 6 upwards and thus over the valve stem 4 the control valve 2 in the opening direction. The path measuring device 11 monitors the stroke of the main piston 6 and reports its position continuously, like that Line of action 40 indicates to the position controller 33. As soon as the specified setpoint of the stroke is reached the position controller 33 controls the proportional directional control valve 25 so that the oil flow is interrupted. The stroke measurement 31, whose signals in the position controller 33 processed, monitors the operating behavior of the proportional directional valve 25. The movement of the main piston 6 is simultaneous with this control completed.

On the other hand, the control valve 2 should be from an open position quickly transferred to a closed state the proportional directional control valve 25 is reversed so that that's to the right of the drawn position standing scheme applies. The connections 29 and 30 are interconnected and oil from the spring chamber 20th flows out through line 47, through the proportional directional valve 25, through lines 51 and 50 further through the buffer volume 8 and the line 52 into the drain device. However, this flow process takes time only for a very short time, as soon as the pressure in the Spring chamber 20 is smaller than the pressure in the drive volume 7, the plate 18 against the pressure of the spring 19 after moved down and the oil from the drive volume 7 flow into the volume 21 and the intermediate volume 24 can and from there further into the drain device. The spring 9 presses the main piston 6 below and thus the oil from the drive volume 7 as long out until the end position of the control valve 2 is reached is. The oil flows out very much quickly since the one released by the plate valve 17 Cross section is comparatively large, so the flow process is not adversely affected by it.

Such rapid pressure relief of the drive volume 7 and such a rapid discharge of the oil from the same would be comparatively small cross sections of lines 47, 51 and 50 are not possible. Would these cross sections and the proportional directional control valve 25 enlarge accordingly, see above could be because of the large, comparatively long None because of the amount of oil to be moved achieve nearly as good dynamics of the actuator 1 as with the embodiment according to the invention.

For the application of the compared to the drive volume 7 very small spring chamber 20 will only requires a comparatively small amount of oil under pressure. This spring chamber 20 is therefore also very much quickly relieved of pressure through lines 47, 51 and 50, if a corresponding control command the proportional directional valve 25 reached. As a result, that immediately after the control command that Plate valve 17 opens and the rapid closing movement the main piston 6 and thus the control valve 2 initiates. The volume of the lines 47, 51, 50 influences therefore not the dynamics of the actuator or only very slightly negative.

In normal operation there are small deviations recognized by the setpoint by the controller 36 and corresponding Correction signals are via the position controller 33 transferred to the proportional directional valve 25. If control valve 2 is to open a little, then only a small amount of oil under pressure in the drive volume 7 replenished until the setpoint is reached again is. For opening movements of the control valve at least one breakthrough through the plate is sufficient 18, as shown in Fig. 2 through the opening 66, in Fig. 3 and Fig. 4 through the aperture 70 and in Fig. 5 by the upper Opening 66 is shown schematically. If the plate 18 is designed according to FIG. 2, so the closing movement the control valve, as already described, initiated by lowering the oil pressure in the spring chamber 20, what if only a small stroke in the closing direction is to make the plate valve 17 only for a short time opens and oil only briefly in volume 21 and the intermediate volume 24 can escape. Once the The setpoint value is reached, the plate valve 17 closes immediately again.

When the plate 18 is designed according to FIG. 3 can make smaller closing movements without opening of the plate valve 17 take place since through the opening 66 and through the aperture 70 oil from the drive volume 7 can flow into the spring chamber 20 to a Pressure equalization is established as soon as the setpoint is reached is. In this case are larger setpoint deviations to compensate, so opens if the cross sections the opening 66 and the aperture 70 are not sufficient, in addition also briefly the plate valve 17. The The closing process takes place during execution 4 similar to that in the embodiment 3.

The execution of the plate 18 according to FIG. 5 allows also a small closing movement, for larger ones The stroke of the main piston 6 is also in this case It is necessary to open the plate valve 17.

The proportional directional valve 25 is in Fig. 1 in the Center position shown. This is the position if, for example, the actuating magnets 26, 27 should not receive voltage due to a power failure. This position is reached by spring force from inside the proportional directional valve 25 provided springs ensured under all circumstances. In this position, the spring chamber 20 is through the lines 47, 51 and 50 relieved of pressure, so that Plate valve 17 opens, as already described, to a quick closing of the control valve 2 leads. This ensures that the control valve 2 Always closed even in the event of a malfunction is, so that under no circumstances damage to the operated turbine due to a defect in the actuator 1 can occur.

The safety valve 49 normally prevents a pressure drop in line 48 towards the drain device. However, if the pressure in the safety oil circuit decreases, so does the pressure in volume 55 and the safety valve 49 is there regardless of that Position of the proportional directional valve 25, the line 48 free, so that the pressure from the spring chamber 20 of the Plate valve 17 can escape through the lines 47, 48 and 50, which, as already described, a rapid closing process of control valve 2 initiated becomes. This measure can also be used in everyone If the steam supply is shut off safely reach the turbine.

When trying to start up, it can happen that that the safety oil circuit is not yet under pressure is set, or not yet put under pressure can. In this case, the directional control valve 58 is installed, which enables once it is switched electromagnetically is drawn to the right of the Position shown scheme that oil under pressure from the line 45 forth through the line 61 and through the Actuate directional valve 58 through volume 55 can, whereby the safety valve 49 is closed becomes. The command route for the directional control valve 58 as he is indicated by the line of action 60, however, blocked as soon as it is switched to normal operation otherwise the safety oil circuit may have an effect no longer on the safety valve 49 is possible, so the protective function of this circuit would no longer be guaranteed.

Should an older actuator be dynamic and also safety-related be strengthened, so it makes sense the plate valve 17, the proportional directional valve 25 and the safety valve 49 to a monolithic Unit. This unit can then Area of the piston-cylinder arrangement of the actuator be installed where there is enough space is.

The pressurized spring chamber 20 and the Sealing points of the plate valve 17 are complete surrounded by low pressure volumes. Should oil fail under high pressure escape from the spring chamber 20, this escapes in the said volumes, so secondary damage can be avoided with great certainty.

Claims (1)

1. Actuating drive (1) for a control valve (2), having a control circuit which sets the actuating drive (1) to correspond with a specified required value from an overriding installation control system, having a main piston (6) sliding in a main cylinder (5), having a drive volume (7), on one side of the main piston (6), which is controlled by a proportional directional valve (25) and can be acted on by oil under pressure, and having a plate valve (17) connected between the drive volume (7) and the proportional directional valve (25), the plate valve (17) having a plate (18) which is held against a seal seat (14b) by a compression spring (19) in a spring space (20) in such a way that the drive volume (7) is separated from the spring space (20),
   characterized

   in that the plate valve (17) is provided with a reservoir volume (21, 24) connected to a drain appliance (24a) and separate from the buffer volume (8) of the actuating drive (1), for oil emerging from the plate valve (17), and

   in that the separate reservoir volume (21, 24) is arranged concentrically around the spring space (20) of the plate valve (17).

Images