CN116679767A - Valve position control system and method - Google Patents

Abstract

The invention relates to a valve position control system and a valve position control method. The valve position control system is used for controlling the valve position of the target regulating valve. In the valve position control system, the common outlet of the switching valve communicates with the actuator of the target regulator valve so that the pressure fluid can be supplied to the actuator of the target regulator valve through the switching valve. The two valve positioners are respectively communicated with the two inlets of the switching valve so that the pressure fluid can be selectively conveyed to the switching valve through the valve positioners and further supplied to the actuating mechanism. In a valve position control system, a switching valve is arranged to be switchable between two switching positions. The valve position control system can ensure the adjustment precision of the target adjusting valve.

Description

Valve position control system and method

Technical Field

The invention relates to the field of industrial control, in particular to a valve position control system and a valve position control method capable of controlling the valve position of a target regulating valve.

Background

In the field of industrial control, information technologies such as control theory, instruments and meters, computers and the like are often required to realize detection, control, optimization, scheduling, management and decision-making of industrial production processes so as to increase yield, improve quality, reduce consumption, ensure safety and the like, thereby realizing industrial control automation.

In the actual production process of automating industrial control, a large number of self-controlled valve systems are required. The self-control valve system is generally composed of a target regulating valve, an actuating mechanism and a control accessory. As one of the control accessories, the valve positioner can remotely adjust the actual opening of the target regulating valve according to the control requirement so as to meet the accurate control of the technological parameters.

With long-term wear of the valve positioner and aging of the internal electronics, the external protection elements, the accuracy of the adjustment of the valve positioner can be reduced or even completely disabled. When the valve positioner fails, the target regulating valve is out of control and deviates from the required control opening, so that accidents in reliability or safety are caused, and certain economic loss is caused for enterprises.

Therefore, it is necessary to provide a solution to ensure the adjustment accuracy of the target adjustment valve.

Disclosure of Invention

The invention aims to provide a valve position control system which can ensure the adjustment precision of a target adjusting valve.

The invention provides a valve position control system which is used for controlling the valve position of a target regulating valve. The target regulator valve has an actuator driven by a pressurized fluid. The valve position control system includes a switching valve, a first valve positioner, and a second valve positioner. The switching valve has a common outlet and first and second inlets selectively communicating with the common outlet, the common outlet of the switching valve communicating with an actuator of the target regulator valve such that pressurized fluid can be supplied to the actuator through the switching valve. The first valve positioner and the second valve positioner are in communication with the first inlet and the second inlet of the switching valve, respectively, such that pressure fluid can be selectively delivered to the switching valve, and thus to the actuator, via either the first valve positioner or the second valve positioner. In a valve position control system, a switching valve is arranged to be switchable between a first switching position and a second switching position. When the switching valve is in the first switching position, the first inlet is communicated with the common outlet. And, the switching valve is in communication with the common outlet at the second switching position.

In one embodiment, the switching valve is a two-position three-way valve.

In one embodiment, the valve position control system further comprises a controller that sends a positioning signal to the first valve positioner and/or the second valve positioner to cause the first valve positioner and/or the second valve positioner to deliver pressurized fluid toward the switching valve according to a preset target valve position.

In one embodiment, the valve position control system further comprises a detector for detecting an actual valve position of the target regulator valve and sending a feedback signal to the controller feeding back the actual valve position.

In one embodiment, the switching valve is a solenoid valve. The controller sends a switching signal to the switching valve according to the feedback signal to switch the switching valve between the first switching position and the second switching position.

In one embodiment, the switching valve is arranged such that the initial position of the switching valve is the first switching position. In the first switching position, the solenoid valve is in an energized state.

In one embodiment, the actuator of the target regulator valve has two chambers that separately contain pressurized fluid. The valve position control system comprises two switching valves, and the common outlet of the two switching valves is respectively communicated with two chambers of an actuating mechanism of the target regulating valve.

In one embodiment, both switching valves are pneumatic valves.

In one embodiment, the valve position control system further comprises a control valve. The control valve is a solenoid valve having a common port and first and second ports selectively communicating with the common port. The common port of the control valve communicates with the pressure gas driven actuators of the two switching valves simultaneously, so that pressure gas can be supplied to both switching valves simultaneously through the control valve.

In one embodiment, the control valve is arranged to receive a switching signal from the controller to switch between a first control position and a second control position, and the first port of the control valve is in communication with a source of gas under pressure and the second port is in communication with the atmosphere. In the first control position, the first through port of the control valve is communicated with the common port, and the two switching valves are both positioned at the first switching position. In the second control position, the second port of the control valve communicates with the common port, and as the supply of the pressure gas through the control valve to the actuators of the two switching valves changes, both switching valves switch from the first switching position to the second switching position.

The invention also provides a valve position control method, and the valve position control system is used. In the valve position control method, a controller of the valve position control system always synchronously sends the same positioning signals to a first valve positioner and a second valve positioner.

In the valve position control system and the valve position control method, by arranging the first valve positioner and the second valve positioner, when the control precision of the first valve positioner is insufficient or fails, for example, the first valve positioner is smoothly switched to the second valve positioner to adjust or control the valve position of the target regulating valve, so that the adjustment precision of the target regulating valve can be ensured. In addition, in the valve position control system and the valve position control method, the two valve positioners can be smoothly and freely switched through the arrangement of the switching valves, so that the adjustment precision of the target adjusting valve can be continuously ensured, and the whole switching process is particularly easy to realize automatic control. In addition, the valve position control system is simple in structure and low in cost.

Furthermore, for the double-acting target regulating valve, the valve position control system controls the arrangement of two valve positioners simultaneously by using one control valve, so that the whole structure is simplified to the greatest extent, and the whole control process is simple and easy to implement.

Drawings

The advantages and spirit of the present invention may be further understood by reference to the following detailed description of the invention and the accompanying drawings.

FIG. 1 is a schematic diagram of an exemplary valve position control system according to a first embodiment.

FIG. 2 is a schematic diagram of an exemplary valve position control system according to a second embodiment.

Detailed Description

Specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention should be understood not to be limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known technologies or functions, or other technologies identical to those known technologies.

It should be understood that in the present invention, "at least one (secondary)" means one (secondary) or a plurality of (secondary). "and/or" is used to describe association relationships of associated objects, meaning that there may be three relationships, e.g., "a and/or B" may mean: only a, only B and both a and B are present, wherein a, B may be singular or plural.

The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the present specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

FIGS. 1 and 2 illustrate exemplary configurations of valve position control systems according to two embodiments of the present invention, respectively. It is to be understood that the drawings are by way of example only and are not necessarily drawn to scale and that the scope of the invention should not be construed to be limited thereto.

Fig. 1 shows a first embodiment. As shown in fig. 1, a valve position control system 10 is used to control the valve position of a target regulator valve 20. The target regulator valve 20 has an actuator 201 driven by the pressure fluid f0.

It will be appreciated that the pressure fluid f0 may be a gas such as air or a liquid such as hydraulic oil. Accordingly, the target regulator valve 20 may be a pneumatic regulator valve or a hydraulic regulator valve as a target to be controlled and positioned by the valve position control system 10 or the valve positioners 1, 2 to be mentioned later. In general, the actuator 201 of the target regulator valve 20 may include a cylinder chamber and a piston disposed in the cylinder chamber, the cylinder chamber being partitioned into two separate chambers by the piston, and a pressure fluid may be disposed in the chambers. The piston will displace under the resultant of the forces applied to it by the two chambers. The piston of the actuator 201 will move together with the valve spool of the target regulator valve 20 via the valve stem 202, thus causing the valve spool of the target regulator valve 20 to shift to a different position, i.e. control or adjust the valve position or opening of the target regulator valve 20. Taking the target regulator valve 20 as a common pneumatic diaphragm regulator valve as an example, the piston of the target regulator valve 20 is essentially a deformable diaphragm, and the pressure fluid f0 is air. In fig. 1, for example, in the actuator 201, only one chamber 205 may be required to inject the pressure fluid f0, and another chamber (not shown) may be provided with a spring connected to the piston, for example. At this time, the resultant force applied to the piston mainly derives from the pressing force of the pressure fluid of the chamber 205 and the elastic force of the spring. With the target regulator valve 20 in the form of such a single-acting regulator valve, since the return spring is provided, even if the power is cut off, the target regulator valve 20 (specifically, the spool thereof) can be placed in a reset state, for example, in an off state or a full-on state as needed.

The valve position control system 10 includes a switching valve 3, a first valve positioner 1, and a second valve positioner 2. The switching valve 3 has a common outlet 34, and a first inlet 31 and a second inlet 32 selectively communicating with the common outlet 34. It will be appreciated that by way of example herein, "selectively" means that it is possible to select whether the first inlet 31 or the second inlet 32 communicates with the common outlet 34. Wherein the first inlet 31 is disconnected from the common outlet 34 when the first inlet 31 is in communication with the common outlet 34, and the first inlet 31 is disconnected from the common outlet 34 when the second inlet 32 is in communication with the common outlet 34.

A "valve positioner" is a device that is dedicated to adjusting the position of a target valve. Typically, a conduit delivering fluid from a fluid source supplying the fluid, such as the air source 8 of fig. 1, to a target valve (specifically, its actuator) will pass through a valve positioner. After passing the valve positioner, the fluid pressure may be adjusted, thereby adjusting, for example, the resultant force of the two chambers of the target regulator valve 20 against the piston, thereby adjusting the valve position of the target regulator valve 20. That is, the outputs of the valve positioners 1, 2 are sent to the actuator 201 (specifically, the chamber in the cylinder chamber) of the target regulator valve 20 to control the target regulator valve 20 to the specified opening degree. The solid lines marked with double diagonal bars in the figures may each represent a conduit that allows fluid to pass through. The dashed lines may represent signal transmissions between two elements, either by wired or wireless connections.

The common outlet 34 of the switching valve 3 communicates with the actuator 201 of the target regulator valve 20 so that the pressure fluid f0 can be supplied to the actuator 201 through the switching valve 3. It is to be understood that "in communication" with one element or location and another element or location means that the two elements or locations are fluidly connected to each other, and "disconnected" means that fluid flow between the two elements or locations is blocked, i.e., fluid flow from one element or location to the other element or location is inhibited. For example, the two elements are connected by a conduit so as to be able to transfer fluid unidirectionally or bidirectionally with each other. The aforementioned common outlet 34 communicates with the actuator 201, meaning that fluid can flow between the common outlet 34 and a chamber in the cylinder chamber of the actuator 201.

The first valve positioner 1 and the second valve positioner 2 are in communication with a first inlet 31 and a second inlet 32, respectively, of the switching valve 3 such that the pressure fluid f0 can be selectively delivered through the first valve positioner 1 or the second valve positioner 2 to the switching valve 3 for supply to the actuator 201. That is, the output ends of the two valve positioners 1, 2 are respectively communicated with the two inlets 31, 32 of the switching valve 3, and the outputs of the two valve positioners 1, 2 are sent to the target regulating valve 20 via the switching valve 3.

Similar to the above, here "selectively" means whether the pressure fluid f0 passes through the first valve positioner 1 or the second valve positioner 2.

In the valve position control system 10, the switching valve 3 is provided to be switchable between the first switching position A1 and the second switching position A2. The switching valve 3 is in the first switching position A1, the first inlet 31 communicates with the common outlet 34, which can be seen schematically in the upper half of the switching valve 3 in fig. 1. Also, the switching valve 3, in the second switching position A2, the second inlet 32 communicates with the common outlet 34, which can be seen schematically in the lower half of the switching valve 3 in fig. 1. It will be understood that "switching position", "control position" and the like are intended to refer to the position or state of the corresponding valve, not to the valve itself being in a different position, but to the spool within the valve being in a different position, such that the valve is in a different state or position.

It is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not intended to be limiting with respect to time sequence, number, or importance, and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of features indicated, but merely to distinguish one feature from another. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

As described previously, the switching valve 3 has a first inlet 31, a second inlet 32 and a common outlet 34, wherein the switching valve 3 can be switched between a first switching position A1 and a second switching position A2. In other words, the switching valve 3 is a multi-position, multi-way valve comprising at least two valve positions and three ports. It is to be understood that in the description of the present invention, the meaning of "a plurality" or "a plurality" is two or more, i.e., at least two, unless explicitly specified otherwise. For example, the switching valve 3 may be a three-position four-way valve. As shown in fig. 1, the switching valve 3 may be a two-position three-way valve, so as to make best use of the materials, simplify the structure to the greatest extent, and reduce the cost. Taking the example of a "two-position three-way valve", this means that the valve has three ports, and the valve spool can be switched between two positions, in other words, the valve has two positions. In each valve position, two of the three ports of the two-position three-way valve are in communication, while the other port is closed. It will be appreciated that where restriction of the direction of fluid ingress and egress is intended, the valve port may include an inlet for fluid flow into the valve and an outlet for fluid flow out of the valve. Similarly, the appearances of the phrase "a" or "an" in this document are not meant to be limiting, but rather describing features that have not been apparent from the foregoing. Unless a specific number of a term is intended to include both the singular and the plural, it is meant that the term includes both the singular and the plural.

In the valve position control system 10 described above, by providing the two valve positioners 1, 2, when the control accuracy of one valve positioner, for example, 1, is insufficient or fails, the other valve positioner, for example, 2, is used instead to adjust the opening degree of the target regulator valve 20. Therefore, the adjustment accuracy of the target adjustment valve 20 can be ensured. Further, in the valve position control system 10 described above, by means of the switching valve 3 and the connection and arrangement between the switching valve 3 and the two valve positioners 1, 2, switching between the two valve positioners 1, 2 can be easily achieved, and in particular, automatic switching is facilitated. For example, when the first valve positioner 1 fails or fails, the opening degree of the valve controlled by the first valve positioner 1 can be easily and non-disturbance switched to the control by the second valve positioner 2 by controlling, for example, the valve position switching of the automatic control switching valve 3. When the opening degree of the target regulator valve 20 is adjusted using the second valve positioner 2, the first valve positioner 1 may be repaired or replaced. In this way, in the event of a malfunction or failure of the second valve positioner 2, it is possible to switch back to the use of the first valve positioner 1. Therefore, the adjustment accuracy of the target adjustment valve 20 can be continuously ensured.

In general, the above-described valve position control system 10 ensures the accuracy of adjustment of the target regulator valve 20 by a simple, low-cost construction, improving the reliability and safety of the entire system in which the target regulator valve 20 is used.

As shown in fig. 1, the valve position control system 10 may also include a controller 4. The controller 4 may send a positioning signal Sp to the first valve positioner 1 and/or the second valve positioner 2 to cause the first valve positioner 1 and/or the second valve positioner 2 to deliver the pressure fluid f0 towards the switching valve 3 according to a preset target valve position Pt. The target valve position Pt may be preset, for example, by manual or other device input. In this way, the target regulator valve 20 can receive the pressure fluid f0 from the switching valve 3 so that its valve position is controlled.

As shown in fig. 1, the valve position control system 10 may further include a detector 5 for detecting an actual valve position Pa of the target regulator valve 20 and transmitting a feedback signal Sf to the controller 4 that feeds back the actual valve position Pa. This signal transmission is not shown in fig. 1 for simplicity. Typically, valve positioners are provided with feedback mechanisms for feeding back the actual valve position. In this case, the feedback mechanisms of the valve positioners 1, 2 can together form the detector 5. The detector 5 may be a detection mechanism other than the valve positioners 1 and 2, and may be, for example, a pressure sensor, an optical sensor, an ultrasonic sensor, or the like, and may be provided in the target regulator valve 20, for example, to detect the actual valve position Pa of the target regulator valve 20 by detecting the displacement of the movable valve element in the target regulator valve 20. For simplicity of illustration, some signal connections are not shown, such as between the detector 5 and the controller 4.

In the embodiment shown in fig. 1, the switching valve 3 may be a solenoid valve, and further, a two-position three-way solenoid valve. It will be appreciated that a "solenoid valve", i.e., a valve in which an actuator utilizes electromagnetic force to control a valve position. In fig. 1, the switching valve 3 adopts an electromagnetic valve, so that switching control, particularly automatic switching control, can be facilitated, response is fast, and control stability is high.

The controller 4 may send a switching signal Sw to the switching valve 3 according to the feedback signal Sf to switch the switching valve 3 between the first switching bit A1 and the second switching bit A2. For example, the controller 4 may compare the actual valve position Pa fed back by the feedback signal Sf with a preset target valve position Pt. If the deviation of the actual valve position Pa from the target valve position Pt is too large, for example, greater than a predetermined value, it is determined that the current valve positioner, for example, the first valve positioner 1 is damaged, and the switch is made to use of another valve positioner, for example, the second valve positioner 2.

As shown in fig. 1, the switching valve 3 may be set such that the initial position of the switching valve 3 is the first switching position A1. In other words, the switching valve 3 is initially at the first switching bit A1 at the initial time (i.e., at the very beginning) until the controller 4 gives an instruction of the switching action (i.e., the switching signal Sw). That is, the valve position control system 10 uses the first valve positioner 1 as an initially used valve positioner, and the second valve positioner 2 as a standby valve positioner. At this time, the first valve positioner 1 may be referred to as a primary positioner, and the second valve positioner 2 may be referred to as a secondary positioner or a redundant positioner.

In the illustrated embodiment, in the first switching position A1, the solenoid valve as the switching valve 3 may be in an energized state. That is, initially, the solenoid valve as the switching valve 3 is energized. In other words, in the power-off state, the solenoid valve as the switching valve 3 defaults to the second switching bit A2, but initially, the switching valve 3 is energized. At this time, the switching signal Sw from the first switching bit A1 to the second switching bit A2 may be a power-off signal that powers off the switching valve 3. This may be referred to as a hot standby mode, which facilitates timely discovery of whether the switching valve 3 is malfunctioning.

The controller 4 may be one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), digital signal processing devices (DAPDs), programmable Logic Devices (PLDs), field Programmable Gate Arrays (FPGAs), processors, control devices, microcontrollers, microprocessors, or a combination thereof. The series of related arrangements and operations of the controller 4 described above may further increase the degree of automation of the overall valve position control system 10.

Fig. 2 shows a second embodiment. In fig. 2 and 1, the same or similar elements are given the same or similar reference numerals to omit partial description, so that the overall description is more concise.

As shown in fig. 2, the actuator 201a of the target regulator valve 20a may have two chambers 205, 206 that separately contain the pressure fluid f0. That is, the target regulator valve 20a is a double acting regulator valve, not a single acting regulator valve as shown in fig. 1. As a double-acting regulator valve, both chambers 205, 206 of the target regulator valve 20a, which are separated by a piston such as a diaphragm, may be filled with the pressure fluid f0, and thus the resultant force received by the piston is mainly the resultant force of the pressing forces of the pressure fluid f0 of the two chambers 205, 206.

In fig. 2, the valve position control system 10a may include two of the aforementioned switching valves 3. The common outlet 34 of the two switching valves 3 may be in communication with the aforementioned two chambers 205, 206, respectively, of the actuator 201 of the target regulating valve 20. That is, the common outlet 34 of one switching valve, e.g., 3a, communicates with one chamber, e.g., 205, of the actuator 201 of the target regulator valve 20, while the common outlet 34 of the other switching valve, e.g., 3b, communicates with the other chamber, e.g., 206, of the actuator 201 of the target regulator valve 20.

In other words, the first valve positioner 1 communicates with the first inlet 31 of the switching valve 3a as a whole, while also communicating with the first inlet 31 of the switching valve 3 b. While the second valve positioner 2 communicates with the second inlet 32 of the switching valve 3a and also with the second inlet 32 of the switching valve 3 b. As shown in fig. 2, taking the valve positioners 1 as an example, each valve positioner may include two outlets 14a, 14b (i.e., outlets through the piping of the valve positioner 1 or 2), which outlets 14a, 14b communicate with inlets of the same position of the switching valves 3a, 3b, respectively. It is understood that "co-located inlets" means inlets in both switching valves 3a, 3b that are in communication with or disconnected from the respective common outlet 34 at the same time or under the same conditions (e.g., when both of the pressurized gases g0 are injected into the actuator). That is, the two outlets 14a, 14b of the first valve positioner 1 are respectively in communication with the first inlets 31 of the switching valves 3a, 3b, while the two outlets 14a, 14b of the second valve positioner 2 are respectively in communication with the second inlets 32 of the switching valves 3a, 3 b.

With the valve position control system 10a constructed as described above, the two valve positioners 1, 2 are used to realize the setting of redundant positioners for the target regulator valve 20a in the form of a double-acting regulator valve, as needed from time to time. In general, the valve position control system 10a described above ensures the accuracy of the adjustment of the target regulator valve 20a in the form of a double-acting regulator valve, particularly for large target regulator valves, using an optimized arrangement with fewer components.

In fig. 2, the two switching valves 3 may be pneumatic valves, and further, two-position three-way pneumatic valves. That is, the actuator 301 of the switching valve 3 may be driven by a pressure gas g0 such as air. In other words, pneumatic valves, i.e. valves in which an actuator uses pneumatic force to switch valve positions. When the switching valve 3 is a pneumatic valve, it is convenient to uniformly control by a control valve 6 to be described later.

In fig. 2, the valve position control system 10a may also include a control valve 6, as previously mentioned. The control valve 6 may be a solenoid valve having a common port 64 and first and second ports 61 and 62 selectively communicating with the common port 64. That is, the control valve 6 is a multi-way electromagnetic valve having at least three ports, and the common port 64 may be communicated with the first port 61 or may be switched to be communicated with the second port 62 among the three ports 61, 62, 64. The common port 64 of the control valve 6 may communicate with the actuators 301 of the two switching valves 3 driven by the pressure gas g0 at the same time, so that the pressure gas g0 can be supplied to the actuators 301 of the two switching valves 3 through the control valve 6 at the same time.

As shown in fig. 2, the control valve 6 is arranged to switch between the first control bit B1 and the second control bit B2 in response to a switching signal Sw from the controller 4. The first port 61 and the second port 62 of the control valve 6 may be in communication with the air source 8 and the atmosphere, respectively. Wherein the gas source 8 may supply a pressure gas g0. In this way, the pressure gas g0 can be supplied to the common port 64 and thus the switching valve 3 through the first port 61 of the control valve 6, and the pressure gas g0 can be discharged from the common port 64 through the second port 62 to the outside environment.

In the first control position B1, the first port 61 of the control valve 6 communicates with the common port 64 (which can be seen schematically in the upper half of the control valve 6), both switching valves 3 being located in the first switching position A1. It will be appreciated that in the first control position B1, the second port 62 is disconnected from the common port 64.

In the second control position B2, the second port 62 of the control valve 6 communicates with the common port 64 (this can be seen schematically in the lower half of the control valve 6). It will be appreciated that in the second control position B2, the first port 61 is disconnected from the common port 64. As the supply of the pressure gas g0 through the control valve 6 to the actuators 301 of the two switching valves 3 changes, both switching valves 3 switch from the first switching position A1 to the second switching position A2. It will be appreciated that "supply change" may include switching between supply and outage (i.e., essentially switching the supply flow between a non-zero value and zero) and may also include changing the flow from one non-zero value to another non-zero value different from the one.

In the valve position control system 10a, the control valve 6 in the form of a solenoid valve is provided in cooperation with the switching valve 3 in the form of two pneumatic valves, and the pressure in the two chambers 205 and 206 of the actuator 201a of the target regulator valve 20a can be switched from one valve positioner, for example, 1, to the other valve positioner, for example, 2, by controlling only the control valve 6. Also, it is ensured that the pressures in the two chambers 205, 206 of the actuator 201 are regulated by the same valve positioner, e.g. 1, at each point in time with absolute reliability, which is not prone to errors.

In addition, the control valve 6 adopts a multi-way valve with at least three ports, and can supply the pressure gas g0 and release pressure, so that the valve positioners 1 and 2 can be smoothly switched back and forth, and the reliability, applicability, durability and the like of the whole valve position control system 10a are further improved.

In fact, instead of sending the switching signal Sw to the switching valve 3 in fig. 1, in the valve position control system 10a of fig. 2, the controller 4 sends the switching signal Sw to the control valve 6.

It will be appreciated that the gas source 8 in the figures may be a single unit, such as a tank, or may comprise a plurality of separate units, such as tanks. For example, the gas source 8 may comprise two reservoirs delivering pressure gas g0 towards the control valve 6 and pressure fluid f0 towards the valve positioner 1 or 3, respectively. In the figure, the pressure gas g0 and the pressure fluid f0 are both dry compressed air.

Similar to the previous, the entire valve position control system 10a may also be provided in a hot standby mode. The control valve 6 in the form of a solenoid valve may be initially in an energized state, and the switching valve 3 may be in an aerated state. In other words, when the control valve 6 in the form of a solenoid valve is in the energized state, the pressure gas g0 can be injected into the actuator 301 via the control valve 6, and the switching valve 3 is the first switching bit A1. Whereas the switching valve 3 switches from the first switching position A1 to the second switching position A2 as the pressure gas g0 is no longer supplied or discharged. This hot standby can help to easily and timely find out whether the control valve 6 and the switching valve 3 can operate properly.

The invention also provides a valve position control method. The valve position control method uses the valve position control system 10, 10a described above.

In the valve position control method of the illustrated embodiment, the controller 4 of the valve position control system 10, 10a may be caused to always synchronously transmit the same positioning signal Sp to the first valve positioner 1 and the second valve positioner 2. That is, regardless of whether the first valve positioner 1 or the second valve positioner 2 is currently in use, the controller 4 always keeps sending the positioning signal Sp reflecting the target valve position Pt to the first valve positioner 1 and the second valve positioner 2 at the same time. At this time, the input signals to the main and sub positioners by the controller 4 are always identical. That is, the main positioner and the auxiliary positioner are controlled by the same variable, so that the control is convenient, particularly the control program can be designed very simply, and the problem of signal lag possibly occurring during the switching of the positioners can not be generated. In another embodiment, the controller 4 may also selectively send the positioning signal Sp to the first valve positioner 1 or the second valve positioner 2 according to the feedback signal Sf.

As described above, in particular, in the valve position control method, the controller 4 may automatically switch the switching valve 3 of the valve position control system 10, 10a from the first switching bit A1 to the second switching bit A2 by determining whether the deviation between the target valve position Pt and the actual valve position Pa of the target regulating valve 20, 20a is greater than a predetermined value. More specifically, in the valve position control system 10, the controller 4 causes the switching valve 3 to switch from the first switching bit A1 to the second switching bit A2 by directly transmitting the switching signal Sw to the switching valve 3. In the valve position control system 10a, the controller 4 indirectly causes the switching valve 3 to switch from the first switching bit A1 to the second switching bit A2 by sending the switching signal Sw to the control valve 6.

In one embodiment, switching back from the second switching bit A2 to the first switching bit A1 may be performed manually. For example, the valve position control system 10, 10a may also include a display screen (not shown) through which it may be displayed whether the deviation between the target valve position Pt and the actual valve position Pa is greater than a predetermined value, and the operator may determine whether to switch the secondary positioner back to the primary positioner by visually inspecting the condition displayed on the display screen and further based on the actual condition. As an example, the deviation between the target valve position Pt and the actual valve position Pa may be represented by a straight line distance between the spool positions corresponding to both, and the spool of the target regulator valve 20 should be displaced by a fixed distance according to the target valve position Pt, and the aforementioned predetermined value may be 5% of the fixed distance. At this time, the controller 4 may be prohibited from automatically switching the secondary positioner back to the primary positioner. This prevents the master locator from switching back without failure. The valve position control system 10, 10a may also include an alarm. The alarm may sound an alarm when the deviation between the target valve position Pt and the actual valve position Pa is too large, indicating that the currently in use positioner is malfunctioning.

In the valve position control system, each component can be automatically controlled through an automatic program. When it is determined that the main positioner used by default or initially is abnormal or failed, the automatic control solenoid valve is immediately de-energized, while the output is switched to the sub-positioner to keep the target regulator valve under normal control.

Each aspect or embodiment defined herein may be combined with any other aspect or aspects or embodiment unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

The preferred embodiments of the present invention are described in this specification, which are intended to be illustrative of the technical solution of the present invention and not limiting. All technical solutions that can be obtained by logic analysis, reasoning or limited experiments according to the inventive concept by those skilled in the art shall be within the scope of the present invention.

Claims (11)

1. A valve position control system for controlling a valve position of a target regulator valve having an actuator driven by a pressurized fluid, comprising:

a switching valve having a common outlet and first and second inlets selectively communicating with the common outlet, the common outlet of the switching valve communicating with the actuator of the target regulator valve to enable the supply of the pressure fluid to the actuator through the switching valve; and

a first valve positioner and a second valve positioner in communication with the first inlet and the second inlet, respectively, of the switching valve such that the pressure fluid can be selectively delivered to the switching valve, and thus to the actuator, via either the first valve positioner or the second valve positioner;

in the valve position control system, the switching valve is arranged to be switchable between a first switching position and a second switching position, the first inlet is communicated with the common outlet when the switching valve is in the first switching position, and the second inlet is communicated with the common outlet when the switching valve is in the second switching position.

2. A valve position control system as defined in claim 1, wherein the switching valve is a two-position three-way valve.

3. A valve position control system as defined in claim 1, further comprising a controller to send a positioning signal to the first valve positioner and/or the second valve positioner to cause the first valve positioner and/or the second valve positioner to deliver pressurized fluid to the switching valve according to a preset target valve position.

4. A valve position control system as defined in claim 3, further comprising a detector to detect an actual valve position of the target regulator valve and to send a feedback signal to the controller that feeds back the actual valve position.

5. A valve position control system as defined in any one of claims 1 to 4, wherein the switching valve is a solenoid valve;

the controller sends a switching signal to the switching valve according to the feedback signal to switch the switching valve between the first switching position and the second switching position.

6. A valve position control system as defined in claim 5, wherein the switching valve is configured such that an initial position of the switching valve is the first switching position;

in the first switching position, the electromagnetic valve is in an energized state.

7. A valve position control system as defined in any one of claims 1 to 4, wherein the actuator of the target regulator valve has two chambers that separately contain the pressurized fluid;

the valve position control system comprises two switching valves, and the common outlet of the two switching valves is respectively communicated with the two chambers of the actuating mechanism of the target regulating valve.

8. A valve position control system as defined in claim 7, wherein both switching valves are pneumatic valves.

9. A valve position control system as defined in claim 8, further comprising a control valve that is a solenoid valve having a common port and first and second ports selectively communicating with the common port;

the common port of the control valve communicates with the pressure gas driven actuators of the two switching valves simultaneously, thereby enabling the pressure gas to be supplied to the two switching valves simultaneously through the control valve.

10. A valve position control system as defined in claim 9, wherein the control valve is configured to receive a switching signal from a controller to switch between a first control position and a second control position, and wherein the first port of the control valve is in communication with a source of gas supplying the pressurized gas and the second port is in communication with the atmosphere;

in the first control position, the first port of the control valve is communicated with the common port, and the two switching valves are both positioned at a first switching position;

in the second control position, the second port of the control valve is communicated with the common port, and as the supply of the pressure gas to the actuating mechanisms of the two switching valves through the control valve changes, the two switching valves are switched from the first switching position to the second switching position.

11. A valve position control method, characterized in that a valve position control system according to any one of claims 1 to 10 is used,

in the valve position control method, a controller of the valve position control system always synchronously sends the same positioning signals to a first valve positioner and a second valve positioner.