Electric actuator and method of replacing an electric actuator of a valve without outage

Abstract

An electric actuator and a method for replacing a valve electric actuator without downtime are disclosed. The electric actuator includes: an LCD screen for receiving input absolute coded values ​​corresponding to the valve positions at both ends of the valve, and sending the absolute coded values ​​to a main control board; a main control board for receiving the absolute coded values ​​sent by the LCD screen and controlling the motor to rotate; an absolute encoder for detecting the rotation of the motor and outputting a serial port signal or other electrical signal to the main control board; the main control board for sending the serial port signal or other electrical signal to a signal output card; a signal output card for receiving the signal output by the main control board and converting it into an analog electrical signal or other electrical signal for transmission to the control system; and the control system converting the received signal into the corresponding absolute coded value. This invention enables the replacement of valve electric actuators without interrupting production.

Description

Technical Field

[0001] This invention relates to the field of electric actuators in automated instruments, and in particular to an electric actuator and a method for replacing valve electric actuators without downtime. Background Technology

[0002] In industrial production systems, electric actuators are widely used as the operating mechanisms for pipeline valves to achieve the opening, closing, and linear adjustment of the opening degree of various process media within the pipeline, thereby automating the entire process system. Common examples include boiler feedwater valves in power plants and reactor feed valves in chemical plants. Generally, the time difference between the opening and closing of valves is significant. For instance, boiler feedwater valves in power plants need to remain fully open during normal generator operation, only actuating to the fully closed position during shutdown or when the boiler is full. In other words, some or most important valves in the process flow are normally prohibited from moving to the other end of their position. However, if an electric actuator, as the valve's operating mechanism, experiences a serious malfunction, replacing the internal control board or even the first new electric actuator requires recalibration and repositioning, operating in both fully open and fully closed directions. Otherwise, the electric actuator cannot properly drive the valve and stop at the correct end position, nor can it send feedback signals indicating that the valve is fully open or closed. This prevents the process control system (such as DCS or PLC) from effectively transmitting signals and continuing control. Therefore, when most industrial enterprises experience serious malfunctions in valve electric actuators, they typically disable the electric operation function for valves of less critical importance, resorting to manual operation only when necessary, until a process system shutdown is available for replacement and adjustment. For critical valves, however, only partial or complete production system shutdowns are possible, necessitating immediate replacement of the electric actuator, often resulting in indirect economic losses exceeding hundreds of thousands of yuan. Summary of the Invention

[0003] The main objective of this invention is to propose an electric actuator and a method for replacing valve electric actuators without interrupting production, enabling the replacement of valve electric actuators without stopping the production system.

[0004] The present invention adopts the following technical solution:

[0005] On the one hand, a method for replacing valve electric actuators without downtime includes:

[0006] Disconnect the old electric actuator from the valve connection to obtain the valve's specifications; the specifications include the valve stem and the valve boss.

[0007] The valve specifications are verified using the commissioning assembly, and a suitable commissioning sub-component is selected for the commissioning assembly. Based on the valve specifications and the selected commissioning sub-component, the assembly plate of the first new electric actuator is selected. The commissioning sub-component includes a bushing and a valve stem that matches the bushing.

[0008] The first new electric actuator is connected to the commissioning assembly via the assembly plate, and the power supply is connected to the commissioning assembly as a valve reference to complete the positioning and commissioning.

[0009] Disconnect the first new electric actuator from the commissioning assembly, and connect the first new electric actuator to the valve connection.

[0010] Preferably, the positioning and debugging method includes:

[0011] Drive the first new electric actuator to actually operate to the first position of the debugging component. Access the LCD screen setting menu of the first new electric actuator via remote control or touch control, select the valve position positioning item in the valve position setting sub-menu, and set the first position to an end valve position.

[0012] Drive the electric actuator to the second position of the debugging component. Access the LCD screen setting menu of the first new electric actuator via remote control or touch. Select the valve position setting item in the valve position setting submenu and set the second position to another end valve position.

[0013] Preferably, for electric actuators with equivalent design, the replacement method for the next non-stop replacement includes:

[0014] Disconnect the first new electric actuator from the valve connection and connect the second new electric actuator to the valve connection.

[0015] If the current valve position is fully open, then set the current absolute code value of the second new electric actuator to one end valve position, and subtract the difference between the two ends of the historical control code value from the current absolute code value of the second new electric actuator to set the other end valve position;

[0016] If the current valve position is fully closed, then set the current absolute code value of the second new electric actuator to one end valve position, and add the difference between the two ends of the historical control code value to the current absolute code value of the second new electric actuator to set the other end valve position;

[0017] If the current valve position is the middle position, then based on the percentage of the full stroke at the middle position, the current absolute code value of the second new electric actuator is proportionally subtracted from the difference between the two ends of the historical control code value to set it as an end valve position; the current absolute code value of the second new electric actuator is proportionally added to the difference between the two ends of the historical control code value to set it as another end valve position.

[0018] Preferably, the method for setting the absolute encoded value to the end valve position includes:

[0019] Access the LCD screen setting menu of the second new electric actuator via remote control or touch screen, and select the coded value positioning item in the valve position setting submenu to set it.

[0020] On the other hand, a debugging component includes: a connecting mechanism, a shaft assembly, a valve stem, a fixing rod, and a screw; one end of the connecting mechanism is engaged with a circular boss of the assembly, and the other end is connected to the shaft assembly; the valve stem passes through the internal threaded hole of the shaft assembly and is matched with the internal threaded hole; a first through hole is provided at the end of the valve stem, and the screw is provided with a graduated through hole, the screw passing through any screw hole on the assembly plate of the electric actuator and being threadedly connected to the screw hole of the assembly plate of the electric actuator; one end of the fixing rod passes through the first through hole and is fixed, and the other end of the fixing rod passes through the graduated through hole; after being powered on, the electric actuator drives the circular boss to rotate, and the rotation amount drives the shaft assembly to rotate through the connecting mechanism. The rotation amount of the shaft assembly is converted through the screw and the fixing rod, driving the valve stem to move up and down, driving the fixing rod to move up and down in the graduated through hole, recording the corresponding travel distance, and completing the positioning debugging.

[0021] Preferably, the connecting mechanism includes: an adjusting gear, an arc-shaped adjusting rack, an arc-shaped hollow cavity, a universal joint, and a first connecting part; the arc-shaped adjusting rack and the arc-shaped hollow cavity are connected in an arc-shaped track manner; the arc-shaped adjusting rack and the arc-shaped hollow cavity are connected to the first connecting part through the universal joint; one end of the arc-shaped adjusting rack includes a first metal top block, and one end of the arc-shaped hollow cavity includes a second metal top block; the circular boss includes two or more, and rotating the adjusting gear can make the first metal top block, the second metal top block, and the two circular bosses closely fit together; the shaft assembly includes a second connecting part; the first connecting part and the second connecting part are fixedly connected; the universal joint includes a first universal joint and a second universal joint; the first universal joint is used to adjust the outward radius, and the second universal joint is used to make the arc-shaped adjusting rack and the arc-shaped hollow cavity perpendicular to the assembly.

[0022] Preferably, the shaft assembly includes two or more bushings; each bushing has a different inner diameter and thread specification, but the same outer diameter; the valve stem includes two or more valve stems; each valve stem has a different outer diameter and thread specification; in use, a bushing that matches the outer diameter and thread profile of the valve stem is selected, and a valve stem that matches the bushing is selected for positioning and adjustment; after use, the bushings are locked together.

[0023] Preferably, the end of the fixing rod that passes through the first through hole is provided with threads, and is fixedly connected to the valve stem by a locking nut; each valve stem is threaded onto the fixing rod through the first through hole for storage after use.

[0024] On the other hand, an electric actuator includes an LCD screen, a main control board, a motor, an absolute encoder, and a signal output card;

[0025] The LCD screen is used to receive input absolute code values ​​corresponding to the valve positions at both ends of the valve, and send the absolute code values ​​to the main control board;

[0026] The main control board is used to receive the absolute code values ​​sent by the LCD screen that correspond to the valve positions at both ends of the valve, and to control the motor to rotate.

[0027] The absolute encoder is used to detect the rotation of the motor and output serial port signals or other electrical signals to the main control board.

[0028] The main control board is also used to send the serial port signal or other electrical signals to the signal output card;

[0029] The signal output card is used to receive the signal output by the main control board and convert it into a 4-20mA analog electrical signal or other electrical signal and send it to the control system; the control system converts the received signal into the corresponding absolute encoding value.

[0030] On another front, a method for replacing valve electric actuators without downtime is provided, wherein both the old electric actuator to be replaced and the new electric actuator to be replaced are based on the aforementioned electric actuator, and the replacement method includes:

[0031] Disconnect the old electric actuator from the valve connection and connect the new electric actuator to the valve connection.

[0032] If the current valve position is fully open, set the current absolute code value of the new electric actuator to one end valve position, and subtract the difference between the two ends of the historical control code value from the current absolute code value of the new electric actuator to set the other end valve position.

[0033] If the current valve position is fully closed, set the current absolute code value of the new electric actuator to one end valve position, and add the difference between the two ends of the historical control code value to the current absolute code value of the new electric actuator to set the other end valve position.

[0034] If the current valve position is the middle position, then based on the percentage of the full stroke at the middle position, the current absolute code value of the new electric actuator is proportionally subtracted from the difference between the two ends of the historical control code value to set it as an end valve position; the current absolute code value of the new electric actuator is proportionally added to the difference between the two ends of the historical control code value to set it as another end valve position.

[0035] The difference between the two ends of the historical control code value is equal to the statistical value of the difference between the absolute code values ​​of the valve after it stops operating between the fully open and fully closed positions when the old electric actuator is intact in the historical database of the control system.

[0036] Methods for setting absolute encoded values ​​to end valve positions include:

[0037] Access the LCD screen setting menu of the new electric actuator via remote control or touch screen, and select the coded value positioning item in the valve position setting submenu to set it.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) The present invention achieves the positioning and debugging of the valve positions at both ends of the new electric actuator through the debugging component, thereby enabling the replacement of the valve electric actuator without stopping the production system;

[0040] (2) The positioning and debugging method of the present invention includes two types. The first type is to drive the new electric actuator to actually operate to two positions to obtain the two end valve positions. The second type is that when the electric actuator including the absolute encoder needs to be replaced, if it is replaced with a new electric actuator with the same design (the new electric actuator is an electric actuator with settable absolute coding value), then it is only necessary to set the two end valve positions according to the historical control coding value and the current absolute coding value of the electric actuator to be replaced. Using the second positioning and debugging function can further speed up the replacement of electric actuators, and the setting is simple and convenient.

[0041] (3) The debugging component of the present invention has a simple structure and is easy to carry. It is equipped with multiple optional bushings, valve stems and multiple sets of connecting mechanisms with adjustable fitting bosses, which can quickly meet the replacement needs of various electric actuators. The screw of the debugging component of the present invention is provided with a scale, so the corresponding stroke can be observed intuitively. In addition, the debugging component of the present invention can also be used for no-load testing of electric actuators before leaving the factory or before use, and to test no-load torque, stroke actuation rate and / or other parameters.

[0042] (4) An electric actuator of the present invention, wherein the electric actuator of this embodiment includes an LCD screen, a main control board, a motor, an absolute encoder and a signal output card; after the new electric actuator is connected to the valve, it only needs to set the absolute encoding value of the corresponding two end valve positions through the LCD screen, and no longer needs to be re-adjusted and positioned, that is, it does not need to move in the two directions of fully open and fully closed respectively, and can be replaced without stopping the production system. Attached Figure Description

[0043] Figure 1 This is a flowchart of the valve electric actuator replacement method without downtime according to Embodiment 1 of the present invention;

[0044] Figure 2 This is a flowchart illustrating the overall process of replacing and debugging the valve electric actuator without downtime, as described in Embodiment 1 of the present invention.

[0045] Figure 3 This is a block diagram of an electric actuator with configurable absolute encoding values;

[0046] Figure 4 This is a cross-sectional view (AA) of the assembly disc and circular boss in Embodiment 1 of the present invention;

[0047] Figure 5 This is a plan view of the assembly and debugging components according to Embodiment 1 of the present invention;

[0048] Figure 6 This is a perspective view of the assembly and debugging components according to Embodiment 1 of the present invention;

[0049] Figure 7 This is a flowchart of the valve electric actuator replacement method without downtime according to Embodiment 2 of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] See Figure 1 and Figure 2 As shown, a method for replacing a valve electric actuator without downtime includes:

[0053] S101, disconnect the old electric actuator from the valve connection and obtain the valve's specification data; the specification data includes the valve stem specification data and the valve boss specification data;

[0054] S102, Use the commissioning component to verify the valve's specifications and select a suitable commissioning sub-component for the commissioning component; Based on the valve's specifications and the selected commissioning sub-component, select the assembly plate of the first new electric actuator; The commissioning sub-component includes a bushing and a valve stem that matches the bushing;

[0055] S103, the first new electric actuator is connected to the debugging component through the assembly plate, and the power supply is connected to complete the positioning debugging by using the debugging component as a valve reference;

[0056] S104, disconnect the first new electric actuator from the commissioning assembly, and connect the first new electric actuator to the valve connection.

[0057] Specifically, in S101, the valve specification data can be obtained through simple measurement and debugging, or it can be obtained based on the valve's known parameters. The specification data includes the specifications of the valve stem and the valve boss. More specifically, it can include the valve stem diameter, thread profile, mounting screw hole spacing and diameter, inner and outer diameters of the assembly body, number of valve bosses, and height arc radius, etc.

[0058] In S102, the valve specification data is verified using the commissioning component. Suitable commissioning sub-components are selected for the commissioning component, and this is obtained through simple measurement and commissioning. Specific methods may include:

[0059] Using the bushings of the debugging components, match the inner diameter and tooth profile of the valve stem that has been detached from the assembly and exposed at the end. After the bushings fit, select the bushing and select the debugging valve stem with the matching outer diameter and tooth profile.

[0060] In S103, the first new electric actuator is connected to the commissioning assembly via the assembly plate, and a power supply is connected to use the commissioning assembly as a valve reference to complete the positioning and commissioning. Specific methods may include:

[0061] The specifications of the valve's meshing and transmission parts (valve boss and valve stem specifications) are copied to the commissioning assembly. The specifications of the first new electric actuator assembly plate are then selected using this commissioning assembly. The connecting mechanism of the commissioning assembly is extended outwards to match the radius from the valve boss to the valve stem center, and the extension and retraction of the metal top blocks at both ends are made to match the arc length of the valve boss. The height of the valve boss is then measured and compared. The specifications of the first new electric actuator assembly plate 13 are determined using the verified measurement data (this may be a temporary machining or supplied together with the electric actuator; assembly plate 13 is not part of the commissioning assembly but is a component of the electric actuator).

[0062] It should be noted that the valve boss refers to the circular boss of the valve; the valve stem refers to the valve stem.

[0063] Specifically, the positioning and debugging method includes:

[0064] Drive the first new electric actuator to actually operate to the first position of the debugging component. Access the Chinese LCD screen setting menu of the first new electric actuator via remote control or touch control, select the valve position positioning item in the valve position setting sub-menu, and set the first position to an end valve position.

[0065] Drive the first new electric actuator to the second position of the debugging component. Access the Chinese LCD screen setting menu of the first new electric actuator via remote control or touch control. Select the valve position setting item in the valve position setting submenu and set the second position to another end valve position.

[0066] Specifically, the distance between the first position and the second position is set based on design data such as pipe diameter (process pipe diameter of valve isolation), valve flow diameter, and / or valve opening / closing position scale and commissioning record data.

[0067] Furthermore, if the first new electric actuator is as follows: Figure 3 As shown, an absolute encoder is installed. After the first new electric actuator is connected to the valve and put into operation, the absolute encoder will convert the detected motor rotation into a serial port signal or other electrical signal and output it to the main control board. The serial port signal or other electrical signal received by the main control board is converted into a 4-20mA analog electrical signal or other electrical signal by the signal output card and sent to the control system (such as DCS control system, PLC control system, etc.). In the control system, the corresponding electrical signal is converted into an absolute code value and stored, and recorded as a historical control code value.

[0068] Furthermore, for electric actuators with equivalent design, the portable commissioning kit is no longer required as a reference during the next no-downtime replacement; only the historical control coding values ​​of the valve recorded by the control system need to be used. Specifically, the first new electric actuator should be replaced and commissioned as follows:

[0069] Disconnect the first new electric actuator from the valve connection and connect the second new electric actuator to the valve connection.

[0070] If the current valve position is fully open, then set the current absolute code value of the second new electric actuator to one end valve position, and subtract the difference between the two ends of the historical control code value from the current absolute code value of the second new electric actuator to set the other end valve position;

[0071] If the current valve position is fully closed, then set the current absolute code value of the second new electric actuator to one end valve position, and add the difference between the two ends of the historical control code value to the current absolute code value of the second new electric actuator to set the other end valve position;

[0072] If the current valve position is the middle position, then based on the percentage of the full stroke at the middle position, the current absolute code value of the second new electric actuator is proportionally subtracted from the difference between the two ends of the historical control code value to set it as an end valve position; the current absolute code value of the second new electric actuator is proportionally added to the difference between the two ends of the historical control code value to set it as another end valve position.

[0073] The difference between the two ends of the historical control code value is equal to the statistical value of the difference between the absolute code values ​​of the electric actuator when it was in good condition and stopped operating between the fully open and fully closed positions in the historical database of the control system.

[0074] In one embodiment, if the difference between the two ends of the historical control code value obtained according to the above method is equal to 200, and the current valve position is fully closed and the current absolute code value is 800, then 800 is set as one end valve position and 1000 is set as another end valve position; if the current valve position is fully open and the current absolute code value is 1000, then 1000 is set as one end valve position and 800 is set as another end valve position; if the current valve position is 50% of the full stroke and the current absolute code value is 900, then 800 is set as one end valve position and 1000 is set as another end valve position.

[0075] Specifically, methods for setting absolute encoded values ​​to the end valve position include:

[0076] Access the Chinese LCD screen setting menu of the second new electric actuator via remote control or touch screen, and select the coded value positioning item in the valve position setting submenu to set it.

[0077] See Figures 4 to 6 As shown, this embodiment of a debugging component includes: a connecting mechanism, a shaft assembly, a valve stem, a fixing rod 11, and a screw 12; one end of the connecting mechanism is nested with a circular boss 131 of the assembly, and the other end is connected to the shaft assembly; the valve stem passes through the internal threaded hole 8 of the shaft assembly and is matched with the internal threaded hole 8; a first through hole 101 is provided at the end of the valve stem, and the screw 12 is provided with a graduated through hole 121. The screw 12 passes through any screw hole 132 on the assembly plate 13 of the electric actuator and is matched with the screw hole 121 of the assembly plate 13 of the electric actuator. 32 is threaded and locked and limited by positioning nut 122; one end of the fixing rod 11 passes through the first through hole 101 and is fixed, and the other end of the fixing rod 11 passes through the graduated through hole 121; after power is applied, the electric actuator drives the circular boss 131 to rotate, and the rotation amount drives the shaft assembly to rotate through the connecting mechanism. The rotation amount of the shaft assembly is converted by the screw and the fixing rod 11, driving the valve stem to move up and down, and driving the fixing rod 11 to move up and down in the graduated through hole 121, recording the corresponding stroke distance, and completing the positioning and debugging.

[0078] It should be noted that the circular boss 131 refers to the circular boss of the new electric actuator assembly, and the valve stem refers to the multiple valve stems 10 adapted to the debugging assembly.

[0079] Furthermore, the connecting mechanism includes: an adjusting gear 1, an arc-shaped adjusting rack 2, an arc-shaped hollow cavity 3, a universal joint, and a first connecting part 5; the arc-shaped adjusting rack 2 and the arc-shaped hollow cavity 3 are connected in an arc-shaped track manner; the arc-shaped adjusting rack 2 and the arc-shaped hollow cavity 3 are connected to the first connecting part 5 through a universal joint; one end of the arc-shaped adjusting rack 2 includes a first metal top block 21, one end of the arc-shaped hollow cavity 3 includes a second metal top block 31, and the circular boss 131 includes two or more, and rotating the adjusting gear 1 can make the first metal top block 21, the second metal top block 31 and the two circular bosses 131 of the electric actuator closely fit together; the shaft assembly includes a second connecting part 7; the first connecting part 5 and the second connecting part 7 are fixedly connected.

[0080] It should be noted that the connecting mechanism also includes a locking device (not shown in the figure). After the left and right rotation of the adjusting gear expands the arc-shaped adjusting rack 2 and the arc-shaped hollow cavity 3, they are locked by the locking device. Otherwise, the force transmitted from the circular boss will recompress the distance between the two metal top blocks.

[0081] The adjusting gear 1 has a segmented structure. Pulling it out vertically causes the adjusting gear to embed into the arc-shaped adjusting rack 2. Pushing it in vertically causes the adjusting gear to disengage from the rack. Elastic locking components such as positioning pins or locking devices engage with the arc-shaped rack and the arc-shaped hollow cavity in the movement gap.

[0082] Specifically, the universal joint includes a first universal joint 41 and a second universal joint 42; the first universal joint 41 is used to adjust the outward radius, and the second universal joint 42 is used to make the arc-shaped adjusting rack 2 and the arc-shaped hollow cavity 3 perpendicular to the assembly. It should be noted that if the adaptation radius adjustment range is large, more universal joints can be added or the connecting rod between the two universal joints can be lengthened.

[0083] The shaft assembly includes two or more bushings 6; each bushing 6 has a different inner diameter and thread specification, but the same outer diameter. The valve stem assembly includes two or more valve stems 10; each valve stem 10 has a different outer diameter and thread specification. In use, a bushing 6 matching the outer diameter and thread type of the valve stem is selected, and a valve stem 10 matching the bushing 6 is selected for positioning and adjustment. After use, the bushings 6 are locked together. After use, the valve stem 10 is hooked to the fixing rod 11 through the through hole 101 for easy carrying and storage.

[0084] The fixing rod 11 has threads at one end passing through the first through hole 101 and is fixedly connected to the valve stem by a locking nut 14. Specifically, the circular boss 131 includes 2, 3, 4 or more, as shown in this embodiment. Figure 4The figure shows three. Accordingly, in the implementation, three sets of connecting mechanisms are used, mounted at a 120° angle to the bushing 6, and engaged with the circular boss; only one set is shown in the figure.

[0085] See Figure 5 and Figure 6 As shown, the debugging assembly consists of three parts: an adjusting gear 1, an arc-shaped adjusting rack 2, an arc-shaped hollow cavity 3, a universal joint 4, and a first connecting part 5, forming a connecting mechanism (i.e., an adjustable engagement circular boss 131 mechanism). In this embodiment, the right end of the arc-shaped adjusting rack 2 includes a first metal top block 21; the left end of the arc-shaped hollow cavity 3 includes a second metal top block 31. The lower end of the arc-shaped adjusting rack 2 is connected to the arc-shaped hollow cavity 3 via an arc-shaped track. The first universal joint 41 and the second universal joint 42 are angle-adjustable rigid constant velocity universal joints. The first connecting part 5 includes a through hole for bolts. The function of the connecting mechanism is to contract inward or expand outward through the first universal joint 41, and to make the arc-shaped adjusting rack 2 and the arc-shaped hollow cavity 3 perpendicular to the assembly through the second universal joint 42, and to rotate the adjusting gear 1 to make the first metal top block 21, the second metal top block 31, and the two circular bosses 131 of the electric actuator closely engage.

[0086] The shaft assembly includes separable, multi-section lightweight material (such as POM, commonly known as acetal steel) shaft sleeves 6 with different internal diameters. The internal threaded hole 8 is manufactured according to the diameter and thread type of various conventional valve stems. The second connecting part 7 includes multiple (arranged at 60° intervals, adaptable to 2 (180°), 3 (120°) boss structures, or simply 2 of 4 bosses). Each second connecting part 7 includes a through hole for bolts. After selecting a suitable size shaft sleeve 6, the first connecting part 5 and the second connecting part 7 can be tightly connected using double-ended bolts. After use, the second connecting parts 7 of each shaft sleeve 6 are connected to each other using quick-connect locks 9 (the quick-connect type can be a press-type elastic wedge lock and lock sleeve, or a flat-rotation wedge lock and lock sleeve), which is convenient for carrying and storage. The valve stem is made of lightweight material and includes two or more valve stems that are adapted to the bushing 6. After use, each valve stem is hooked to the fixing rod 11 through the through hole 101 for easy carrying and storage. The valve stem tooth profile and outer diameter are matched with the internal thread hole 8, and are selected by comparing with the actual valve connection part in actual use. The fixing rod 11 is an adjustable length semi-threaded fixing member. The end of the valve stem has an opening to insert the fixing rod 11 and is fixed at the left end by a lock nut 14. The screw 12 is a long positioning semi-threaded screw 12. The right end of the fixing rod 11 is toothless and passes through the graduated through hole 121 of the screw 12. After adjusting the length of the fixing rod 11, the long positioning semi-threaded screw 12 is aligned with any screw hole 132 on the assembly plate 13 of the electric actuator so that the thread end of the long positioning semi-threaded screw 12 is connected to the screw hole 132 of the assembly plate 13 of the electric actuator and fixed by a lock nut 122. After the components numbered 1 to 12 are placed with the interface of the circular boss 131 of the assembly plate 13 facing upwards, they are interlocked. When powered on, the electric actuator drives the circular boss 131 to rotate. The rotation amount drives the shaft assembly to rotate through the connecting mechanism. The rotation amount of the shaft assembly drives the valve stem to move up and down, which in turn drives the fixed rod 11 to move up and down in the graduated through hole 121, thereby realizing the valve stroke actuation. The stroke distance is observed in the graduated through hole 121 of the screw 12.

[0087] In this embodiment, once the new electric actuator is positioned and debugged, it can be connected to the valve and put into operation without controlling the valve to move in both fully open and fully closed directions. Therefore, the valve electric actuator can be replaced without stopping the production system, thus preventing economic losses caused by the replacement of the electric actuator.

[0088] Example 2

[0089] See Figure 3 As shown, an electric actuator includes an LCD screen, a main control board, a motor, an absolute encoder, and a signal output card;

[0090] The LCD screen is used to receive input absolute code values ​​corresponding to the valve positions at both ends of the valve, and send the absolute code values ​​to the main control board;

[0091] The main control board is used to receive the absolute code values ​​sent by the LCD screen that correspond to the valve positions at both ends of the valve, and to control the motor to rotate.

[0092] The absolute encoder is used to detect the rotation of the motor and output serial port signals or other electrical signals to the main control board.

[0093] The main control board is also used to send the serial port signal or other electrical signals to the signal output card;

[0094] The signal output card is used to receive the signal output by the main control board and convert it into a 4-20mA analog electrical signal or other electrical signal and send it to the control system; the control system converts the received signal into the corresponding absolute encoding value.

[0095] It should be noted that the main control board saves the absolute code values ​​corresponding to the valve positions at both ends of the valve. Users can also view these values ​​through the LCD screen.

[0096] See Figure 7 As shown, a method for replacing a valve electric actuator without downtime is provided. Both the old electric actuator to be replaced and the new electric actuator to be replaced are based on the aforementioned electric actuator. The replacement method includes:

[0097] S701, disconnect the old electric actuator from the valve connection and connect the new electric actuator to the valve connection;

[0098] S702, if the current valve position is fully open, then set the current absolute code value of the new electric actuator to one end valve position, and subtract the difference between the two ends of the historical control code value from the current absolute code value of the new electric actuator to set the other end valve position;

[0099] S703, if the current valve position is fully closed, set the current absolute code value of the new electric actuator to one end valve position, and add the difference between the two ends of the historical control code value to the current absolute code value of the new electric actuator to set the other end valve position;

[0100] S704 If the current valve position is the middle position, then based on the percentage of the full stroke of the middle position, the current absolute code value of the new electric actuator is proportionally subtracted from the difference between the two ends of the historical control code value to set it as an end valve position; the current absolute code value of the new electric actuator is proportionally added to the difference between the two ends of the historical control code value to set it as another end valve position.

[0101] Specifically, after the old electric actuator is connected to the valve and put into operation, the absolute encoder of the old electric actuator converts the detected motor rotation into a serial port signal or other electrical signal and outputs it to the main control board. The serial port signal or other electrical signal received by the main control board is converted into a 4-20mA analog electrical signal or other electrical signal by the signal output card and sent to the control system (such as DCS control system, PLC control system, etc.). In the control system, the corresponding electrical signal is converted into an absolute coded value and stored, and recorded as a historical control coded value.

[0102] The difference between the two ends of the historical control code value is equal to the statistical value of the difference between the absolute code values ​​of the electric actuator when it was in good condition and stopped operating between the fully open and fully closed positions in the historical database of the control system.

[0103] In one embodiment, if the difference between the two ends of the historical control code value obtained according to the above method is equal to 200, and the current valve position is fully closed and the current absolute code value is 800, then 800 is set as one end valve position and 1000 is set as another end valve position; if the current valve position is fully open and the current absolute code value is 1000, then 1000 is set as one end valve position and 800 is set as another end valve position; if the current valve position is 50% of the full stroke and the current absolute code value is 900, then 800 is set as one end valve position and 1000 is set as another end valve position.

[0104] Specifically, methods for setting absolute encoded values ​​to the end valve position include:

[0105] Access the Chinese LCD screen setting menu of the new electric actuator via remote control or touch screen, and select the coded value positioning item in the valve position setting submenu to set it. The electric actuator of this embodiment includes an LCD screen, a main control board, a motor, an absolute encoder, and a signal output card. The LCD screen receives input absolute code values ​​corresponding to the valve positions at both ends of the valve and sends these values ​​to the main control board. The main control board receives the absolute code values ​​from the LCD screen and controls the motor to rotate. The absolute encoder detects the rotation of the motor and outputs a serial port signal or other electrical signal to the main control board. The main control board also sends the serial port signal or other electrical signal to the signal output card. The signal output card receives the signal output by the main control board and converts it into a 4-20mA analog electrical signal or other electrical signal, which is then sent to the control system. The control system converts the received signal into the corresponding absolute code value and stores the absolute code. When a new electric actuator with this function is connected to a valve, only the absolute code values ​​corresponding to the valve positions at both ends need to be set via the LCD screen. The new electric actuator then does not need to be re-adjusted and repositioned, meaning it does not need to operate in both fully open and fully closed directions separately, allowing for replacement without interrupting the production system.

[0106] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. An electric actuator, characterized in that, Includes LCD screen, main control board, motor, absolute encoder and signal output card; The LCD screen is used to receive input absolute code values ​​corresponding to the valve positions at both ends of the valve, and send the absolute code values ​​to the main control board; The main control board is used to receive the absolute code values ​​sent by the LCD screen that correspond to the valve positions at both ends of the valve, and to control the motor to rotate. The absolute encoder is used to detect the rotation of the motor and output serial port signals or other electrical signals to the main control board. The main control board is also used to send the serial port signal or other electrical signals to the signal output card; The signal output card is used to receive the signals output by the main control board and convert them into 4-20mA analog electrical signals or other electrical signals and send them to the control system; the control system converts the received signals into corresponding absolute encoded values. The replacement method for the old electric actuator to be replaced and the new electric actuator to be replaced based on the electric actuator includes: Disconnect the old electric actuator from the valve connection and connect the new electric actuator to the valve connection. If the current valve position is fully open, set the current absolute code value of the new electric actuator to one end valve position, and subtract the difference between the two ends of the historical control code value from the current absolute code value of the new electric actuator to set the other end valve position. If the current valve position is fully closed, set the current absolute code value of the new electric actuator to one end valve position, and add the difference between the two ends of the historical control code value to the current absolute code value of the new electric actuator to set the other end valve position. If the current valve position is the middle position, then based on the percentage of the full stroke at the middle position, the current absolute code value of the new electric actuator is proportionally subtracted from the difference between the two ends of the historical control code value to set it as an end valve position; the current absolute code value of the new electric actuator is proportionally added to the difference between the two ends of the historical control code value to set it as another end valve position. The difference between the two ends of the historical control code value is equal to the statistical value of the difference between the absolute code values ​​of the valve after it stops operating between the fully open and fully closed positions when the old electric actuator is intact in the historical database of the control system. Methods for setting absolute encoded values ​​to end valve positions include: Access the LCD screen setting menu of the new electric actuator via remote control or touch screen, and select the coded value positioning item in the valve position setting submenu to set it.

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