DE102014007475B4 - Valve arrangement for controlled pressure relief of fluid-filled lines under increased safety requirements - Google Patents

Abstract

Valve arrangement for controlled pressure relief of fluid-filled lines under increased safety requirements, comprising a drain valve group (16) which is formed from three equal valve units and connected in a 2-by-3 logic valve, which reliably opens the fluid discharge both in regular operation and in the event of a valve unit failure, with main valves, which are designed as hydraulically pilot-operated slide valves with slide valve piston (1, 18, 19), wherein the control of the main valves by a pilot valve (6, 12, 20) per main valve, characterized in that three slide valve housing (2) together with a fourth terminal housing (3, 17) are arranged rotated by 90 ° about a central axis, which thus form a rectangular arrangement together with the terminal housing (3, 17).

Description

There are known valve assemblies for controlled pressure relief fluid-filled lines under increased safety requirements. For applications such. As hydraulically operated Abstellorganen of gas and steam turbines, these are designed so that when switching failure of a single valve element, the switching state of the overall arrangement is not changed. Usual is a 2 out of 3 logic, d. H. only when 2 out of 3 existing valves or valve subgroups switch over the arrangement, the switching state of the overall arrangement changes. Thus, it is ensured that any element or even an entire subset of elements within the overall arrangement may be switched incorrectly, without this having an effect on the underlying plant components. This ensures shutdowns and prevents false shutdowns.

Known arrangements of this type have disadvantages which are described below.

One out EP 2 074 488 B1 known arrangement is based on a valve block with slide valve piston, which are electromagnetically actuated from one side and pressed in the unactuated state on the opposite side of a spring in the opposite direction. For a simple construction of the housing with 3 parallel channel bores here 3 different valve spool valves are required here, since each of the 3 slide valve piston must leave a different of the 3 parallel channel holes permanently consistent. Among other things, this makes the spare parts inventory considerably more expensive.

Known arrangements in which hydraulically pilot operated seat valves ("cartridge valves") are used, in particular as in the concrete material implementation of DE 10 2005 040 039 A1 those of the usual design with only one control terminal without opening acting control surface and thus without vergößerte closing acting control surface (passive cartridge valves), react in their switching behavior z. T. very sensitive to drain-side pressure fluctuations, which are forwarded during the discharge process via the pilot valves directly to the control chamber of the poppet valves. Depending on the type and performance of the upstream fluid supply unit, internal flow resistances and the need of the downstream control device as well as in the pilot valve flow in the pilot valve inlet pressure fluctuations are conceivable that can affect the switching behavior.

In particular, passive cartridge valves usually require the same level of pressure on the control and flow side, an additional closing-acting spring to ensure a safe closing, which (at first) can cause a residual pressure at the port to be controlled when closing the overall arrangement.

For other solutions, such. B. off CH000000699602A1 known, only the hydraulic pilot control in 2 of 3 logic is executed, but not the main fluid flow switching valve. This significantly reduces the achievable safety.

Due to the required safety monitoring of the valve assembly is provided regularly in the known arrangements.

A part of the known arrangements for this purpose has a direct position monitoring of the individual valves, z. B. in the form of a double query for an end position, but not by means of a much more meaningful 2 of 3 logic per valve. Thus, even if one monitoring element fails, a very timely check of the arrangement on site may become necessary.

Another part of the known arrangements has an indirect monitoring, which requires additional components and is therefore dependent on different interactions in their informative value. Especially in the case of a combination of pressure monitoring and diaphragm system, as in DE 10 2005 040 039 A1 described, there is a fundamental disadvantage in the very large dependence of the adjusting pressure of the geometry in the narrowest flow cross-section of the individual panels. Here, in the concrete application, there is a considerable risk with regard to erroneous feedback as a result of contamination of the diaphragm system resulting from thermally induced oxidation of the working fluid and associated z. T. significant deviation of the adjusting at the measuring point pressure.

Depending on the application, this contamination is difficult to avoid depending on the application (or even accepted in part by the plant operator) and may affect the main valves of the arrangement, or their complete reaching the end positions, beyond influencing the diaphragm system. Thus, the position monitoring only an end position of the main valves in this area can lead to a misleading feedback when this end position is not fully achieved due to deposits.

In general, the use of hydraulically piloted poppet valves leads to a large number of mutually mechanically independent moving components, which also suggests a large number of query elements and thus in addition to a higher probability of failure on a regular basis Sides of the control technology caused a considerable effort.

The object of the invention is to avoid the disadvantages mentioned. This object is achieved by a valve arrangement having the features of patent claim 1. Advantageous developments of the invention are the subject of claims 2 to 16.

In the following, various embodiments will be described.

1 shows the basic design of the slide valve piston 1 with slide valve housing 2 , Three of these slide valve housings are common with a fourth connection housing 3 rotated according to claim 1 by 90 ° about a central axis. Section AA shows the interconnection of the corresponding spool valve housing bores. The valve group forms a 2 out of 3 logic, ie the main connections 4 the entire assembly are separated exactly when at least 2 of the 3 slide valve pistons 1 lie in one (here the lower) end position. Conversely, the main ports of the overall assembly are connected if and only if at least 2 of the 3 spool valve pistons 1 lie in the other (here the upper) end position.

2 shows the arrangement 1 matching schematic including the in 1 not indicated pilot valves 6 at the top or bottom of the spool valve piston 1 located end faces 5 alternately pressurize. The shutters connected in the circuit diagram with the pilot control connections 7 on the one hand symbolize the leakage according to claim 2 along the slide valve piston 1 (in 1 ) at the interfaces to the slide valve housing 2 Alternatively, they may also be available as separate elements. In both cases, this causes the pilot valve 6 ago closed pilot control lines, a movement of the slide valve piston 1 in the open position. Thus, a safe end position is already ensured by simply closing the pilot lines. In particular, this tendency can be explained by a section AA in 1 with respect to the horizontal mirror image embodiment, or by reversing connecting the main terminals, be reversed. This may be useful in a second valve group, if in addition to the pressure relief and a shut-off of the inlet to be made possible by this second valve group with its own pilot valves. This variant is discussed below.

The Vorsteuerfluidzu- and -abfuhr takes place in 2 separated from the mains. An alternative thereto according to claim 3 shows 3 , Here is the pilot fluid supply redundant: As long as a significant pressure in RST is pending (only then may still need to switch to the discharge state required, otherwise not more), this is a group of 2 × 2 check valves 8th used for pilot control of the slide valve piston. With this 2 × 2 arrangement ensures that this group even in case of failure of any of the four check valves 8th Overall, their entire function as a check valve completely fulfilled, regardless of whether the failed check valve is open or closed. Thus, even if the actual pilot fluid supply fails, reliable pressure relief can be carried out, depending on the internal frictional resistance of the arrangement, at least up to a reliably low pressure level.

In addition, shows 3 to explain the claim 6, a pressure monitoring 9 the pilot control lines.

Further shows 3 to explain the claim 4 a bilateral, multiple position monitoring 10 the slide valve piston 1 , in particular a triple query. As a special feature, this can not only be evaluated in the form of a 2-out-of-3 logic, but provided with different switching positions (axial switching distances), so that incipient contamination (eg as a result of carbon deposits) is noticed early and comparatively, especially in the area of the limit stops can be reliably diagnosed. Moreover, shows 3 to explain the claim 5, a position monitoring 11 the pilot valves, here for example in a simple single-sided design.

For purposes of saving energy, limiting the heating of the working fluid or other reasons, it may be obvious not only to trigger a pressure relief of Abstellorgans, but also to completely prevent the flow of the working fluid from the fluid supply unit ago. The latter can be done by means of a separate functional unit, which may exist depending on the required security of the shut-off z. B. from one or three individual, simple 2/2-way valves, to a complete second arrangement of the type described so far, which is mounted according to claim 7 between the fluid supply unit and the line to Abstellorgan. For the latter case according to claim 8 is the associated circuit diagram in 4 shown. Here are two pilot valves per total control channel 12 and two slide valve pistons 13 existing, with the previously mentioned pressure or position monitoring 14 can be equipped. Each two pilot valves can be replaced by one each according to claim 9, in the case can also be two Slide valve piston according to claim 10 to be summarized. The possible geometric implementation of the latter design options show the 5 to 7 ,

5 to explain the claims 8 and 9, the arrangement of a feed gate valve group 15 and a drain gate valve group 16 on a common connection housing 17 , The six or three pilot valves are not drawn. The connection of the pilot lines of the upper to the lower slide valve group can be done in the latter case by means of directly abutting frontal surfaces with seal, designed as an intermediate plate valves pilot valves or other means. As indicated earlier, an appropriate design or orientation is the spool valve piston 18 It makes sense, if the pilot lines are closed (increasing the safety, even if this is not to be expected during normal operation), that the inlet leakage valve group is present via the existing leakage 15 in the closed position and the drain gate valve group 16 into the open position.

The same behavior in connection with leakage is also in the explanation of the patent claim 10 in 6 ensured arrangement ensured. Here is an inlet and a drain spool valve piston to a single spool valve piston 19 summarized. This also reduces the number of position monitoring required for equivalent meaningfulness.

An intermediate solution with regard to the suppression of the afterflow shows for explanation of the patent claim 11 7 , Here, the inlet area is not equipped with a 2 out of 3 logic, but behaves similar to the arrangement DE 10 2005 040 039 A1 so that with proper adjustment of the flow resistance in the inlet region in the event of a faulty valve unit only slightly unintentionally nachfließendes working fluid must be additionally dissipated, or only little needed inflowing working fluid fails.

With increasing size also increases the amount of pilot fluid required, if the switching times should not be extended inadmissible. If directional control valve valves are to be used as pilot valves, then it can be seen that above a nominal diameter of 10 mm no uncomplicated connection of insensitive directly operated valves of this design is possible; The next largest design is usually delivered internally hydraulically vorgeteuerter execution. The associated higher sensitivity to contamination and other influences, especially at low operating pressures a significantly increased risk of failure. To avoid this, can be useful per main spool valve piston, a multiple arrangement of directly operated pilot control valves. If these, in the same design per pilot valve as described so far, now in parallel before, then a limitation of the flow, in particular of the respective pilot valve inflowing flow, mounted, in particular in the form of an orifice per pilot valve. This avoids that in the wrong position of a single pilot valve, the pilot fluid inlet is almost unthrottled connected to the -Abfluß.

Is generally an increased pilot fluid consumption for a long time even with such a malfunction is not desirable, then there is a second way to use several, in particular two pilot control valves per main spool valve piston, in an embodiment as described for the explanation of claim 16 below.

8th shows the associated hydraulic circuit diagram in one embodiment of the device only with controlled pressure relief (ie without shutting off the inlet).

The pilot control valves 20 are designed so that they are in an end position, namely the unactuated (currentless) end position two-channel, so with about twice the total flow cross section as before, permeable and shut off in the other end position each compound. They are placed between pilot fluid inlet and main spool valve piston and between main spool valve piston and pilot fluid drain, and move the main spool valve spool in the unactuated (ie, permeable) state to the relief position, respectively. In order to move the main spool valve piston in the opposite direction after closing the pilot control valves, due to the significantly longer time available for a much smaller amount of pilot fluid from which thus z. B. via apertures 21 the two main spool valve piston control surfaces can be supplied. Conversely, these orifices are connected to the pilot fluid inlet and outlet and the main spool valve piston in the same manner as the pilot spool valves.

Since in this arrangement the desired small Vorsteuerfluidströme flow in the opposite direction as before the leakage at the main spool valve piston, a corresponding structure of the main spool valve piston offers the opposite of the representation in 1 at.

The advantage of this design, each with a pilot-way valve per main spool valve piston control surface is mainly that in case of malfunction of a pilot control valve no (especially no permanent) appreciable pilot fluid consumption occurs.

Since, in order to avoid the premature termination of the discharge process due to the diaphragm flow sufficiently long pilot fluid must be available, it is obvious, a group 22 use of check valves according to claim 3, with the existing residual pressure at the discharge port of this residual pressure is forwarded to the pilot valves, even if the regular pilot fluid supply is not available.

In one embodiment of the device with additional shut-off of the inlet of the hydraulic circuit diagram with respect. The pilot valve groups to expand analogous to an extension of 2 on 4 ; or the structure of the main spool valve piston area would be to expand from one to 1 reverse arrangement to an inversion of the spool valve piston structure 6 , which will not be discussed here.

Claims (16)

Valve arrangement for the controlled pressure relief of fluid-filled lines under increased safety requirements, with a drain valve group formed from three equal valve units and connected in 2-by-3-logic ( 16 ), which reliably opens the fluid discharge both in regular operation and in the event of failure of a valve unit, with main valves acting as hydraulically pilot-operated slide valves with slide valve pistons ( 1 . 18 . 19 ), wherein the actuation of the main valves by a pilot valve ( 6 . 12 . 20 ) per main valve, characterized in that three slide valve housing ( 2 ) together with a fourth connection housing ( 3 . 17 ) are arranged rotated by 90 ° about a central axis, which thus together with the terminal housing ( 3 . 17 ) form a rectangular arrangement. Valve arrangement according to claim 1, characterized by an orientation and design of the slide valve piston ( 1 . 18 . 19 ) and / or the slide valve housing ( 2 ) in such a way that with closed pilot control lines and / or in general in the absence of the other on the slide valve piston ( 1 . 18 . 19 Actuating factors triggering an existing leakage by play between slide valve piston ( 1 . 18 . 19 ) and slide valve housing ( 2 ) and / or by additional permeabilities for in the same direction to the aforementioned leakage directed Fluidstömungen, or by diaphragms ( 7 ) between a pilot port and a drain and the other pilot port and the line to the actuator, the slide valve piston ( 1 . 18 . 19 ) is moved to a position corresponding to that in the unloaded state of the overall arrangement. Valve arrangement according to one of the claims 1 to 2, characterized by a direction-dependent flow resistance ( 8th ), which promotes fluid flow from the duct leading to the actuator or from the main inlet to the common pilot fluid supply line, carried out in the form of a group of two or more parallel-connected groups of two or more in series check valves. Valve arrangement according to one of the claims 1 to 3, characterized by a position monitoring ( 10 ) of the spool valve piston, or both end positions in one or more than one per end position, or in 2 of 3 logic per end position and / or with different switching distances in the axial direction for early and reliable detection of deposits. Valve arrangement according to one of the claims 1 to 4, characterized by a one- or two-sided single or multiple, or in 2 out of 3 logic executed position monitoring ( 11 ) of pilot valves ( 6 ). Valve arrangement according to one of the claims 1 to 5, characterized by a pressure monitoring ( 9 ) of the pilot control lines in single or multiple form per pilot line. Valve arrangement according to one of the claims 1 to 6, characterized by an additional device for complete or almost complete suppression of the afterflow of working fluid in the discharge case, by means of a 2/2-way valve in the inlet per drain valve unit, electromagnetically directly actuated, or by its own pilot valve ( 12 ) hydraulically pilot operated, or by the pilot valve ( 13 ) of the respective associated drain valve unit hydraulically piloted. Valve arrangement according to claim 7, characterized by a drain valve group (2) in addition to the in FIG. 16 ) also in 2 from 3 logic designed inlet valve group ( 15 ). Valve arrangement according to one of the claims 7 to 8, characterized by the common pilot control of each one valve unit for inlet and outlet. Valve arrangement according to claim 7, characterized by the summary of each one inlet and outlet valve unit to a single slide valve, which represents a 2 out of 3 logic both in terms of fluid inlet and outlet. Valve arrangement according to claim 7, characterized by the summary depending on an inlet and outlet valve unit to a single slide valve, which represents a 2 out of 3 logic with respect to fluid drain, while the slide valve piston the fluid inlet in parallel, each separately, partially separate or with the line connect to the Abstellorgan. Valve arrangement according to one of the claims 8 to 11, characterized in that in the inlet and / or outlet valve group ( 15 . 16 ), instead of the 2 of 3 logic, there is a similar, higher order ranked logic, such as 3 of FIG. 5 or 4 of FIG. 7, with a correspondingly larger number of valve groups and spool valve control regions and edges. Valve arrangement according to one of the claims 1 to 12, characterized by a direct actuation of the slide valves, electromagnetically, instead of a hydraulic pilot control. Valve arrangement according to one of the claims 1 to 13, characterized by the continuous one-sided loading of some or all slide valve pistons ( 1 . 18 . 19 ) with a force, or by means of spring or fluid pressure. Valve arrangement according to one of the claims 1 to 14, characterized by a reduction of the effective pilot control surfaces of some or all slide valve pistons ( 1 . 18 . 19 ) and thus reducing the effective control oil volumes to increase the switching speed, or by the execution of the spool valve piston ( 1 . 18 . 19 ) with an additional, about the maximum spool valve piston stroke away from the previous end of the spool valve piston and running in a matching housing or housing cover bore piston skirt surface with a smaller diameter and with a low flow connection between the previously existing spool valve piston end face with the full Spool valve piston diameter and the new spool valve piston end face with the smaller diameter of the aforementioned additional piston skirt surface, or with execution of the low-flow connection as a coaxial through-hole through the entire spool valve piston. Valve arrangement according to one of the claims 1 to 15, characterized by two or more pilot valves ( 20 ) per slide valve piston ( 1 ), of which one each two-channel is connected to one of the two slide valve piston end faces, which are further connected to the Vorsteuerfluidzu- and drain that they together in each case in the unactuated state the slide valve piston ( 1 ) move in the relief position and shut off in the actuated state, both slide valve piston end faces from Vorsteuerfluidzu- and drain, and by a construction of the slide valve piston ( 1 ) and the associated permeabilities and / or additional permeabilities or apertures, so that the permeabilities taken to a movement of the spool valve piston ( 1 ) against the relief position, and by ensuring the pilot fluid supply in the absence of external Vorsteuerfluidzufluß, by a compound with directional flow resistance ( 22 ) between the line leading to the actuator and the pilot fluid supply line.

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