Valve element opening degree detection device, hydraulic servo-motor assembly and steam turbine

Abstract

The invention relates to a valve element opening degree detection device, a hydraulic servo-motor assembly and a steam turbine, the valve element opening degree detection device is used for a regulating valve of a hydraulic servo-motor of the steam turbine, the valve element opening degree detection device comprises a linear displacement sensor and an extension piece, and the linear displacement sensor is used for being installed on the hydraulic servo-motor and is provided with a feedback rod extending in the vertical direction; the extension part extends in the vertical direction, the first end of the extension part is connected with the feedback rod, the second end of the extension part is used for being connected with a valve rod stroke fixing support connected to a valve rod of the adjusting valve, and the extension part is constructed to be capable of transmitting displacement of the valve rod stroke fixing support in the vertical direction when the valve rod stroke fixing support moves. The valve rod stroke fixing support can be bent when the moving direction of the valve rod stroke fixing support and the vertical direction form an angle. According to the scheme, the situation that the linear displacement sensor cannot be normally used due to the influence of high temperature is effectively avoided. In addition, the situation that the feedback rod is fractured due to the fact that the feedback rod is subjected to inclined acting force is effectively avoided.

Description

Technical Field

[0001] The present disclosure relates to the technical field of detecting the opening degree of a valve core of a servomotor regulating valve, and specifically, to a device for detecting the opening degree of a valve core, a servomotor assembly, and a steam turbine. Background Art

[0002] The servomotor of a steam turbine is an actuator for regulating the steam valve. It converts the secondary oil signal input by an amplifier or an electro-hydraulic converter into a stroke output with sufficient work capacity to control the regulating valve and the steam inlet of the steam turbine, thereby regulating the rotational speed and load of the steam turbine unit. It is an important part of the steam turbine unit in a thermal power plant.

[0003] In related technologies, a linear displacement sensor (such as an LVDT, i.e., a linear variable differential transformer) is usually arranged at the valve of the regulating valve of the servomotor to detect the opening degree of the regulating valve of the steam turbine servomotor. On the one hand, since the feedback rod of the linear displacement sensor is usually connected to the valve rod through a valve rod stroke fixing bracket, and the distance between the feedback rod and the high-temperature valve is relatively close, the high-temperature valve will affect the resistance characteristics of the sleeve coil of the linear displacement sensor. On the other hand, if the valve rod stroke fixing bracket and / or the valve rod are displaced during use, the feedback rod is easily broken under the inclined acting force. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a device for detecting the opening degree of a valve core, a servomotor assembly, and a steam turbine to solve the technical problems existing in related technologies.

[0005] According to a first aspect of the present disclosure, there is provided a device for detecting the opening degree of a valve core for a regulating valve of a servomotor of a steam turbine, including: A linear displacement sensor for being installed on the servomotor, the linear displacement sensor having a feedback rod extending in the vertical direction; An extension member extending in the vertical direction, a first end of the extension member being connected to the feedback rod, and a second end of the extension member being configured to be connected to a valve rod stroke fixing bracket connected to the valve rod of the regulating valve; Wherein, the extension member is configured to be able to transfer the displacement of the valve rod stroke fixing bracket in the vertical direction when the valve rod stroke fixing bracket moves, and bend when the moving direction of the valve rod stroke fixing bracket forms an angle with the vertical direction.

[0006] Optionally, the device for detecting the opening degree of the valve core further includes a first sleeve and a first nut. The feedback rod passes through the first sleeve and is threadedly connected to the first sleeve. The first nut is threadedly connected to the feedback rod and abuts against one end of the first sleeve close to the linear displacement sensor. The first end of the extension member is connected to the first sleeve.

[0007] Optionally, the first end of the extension member is inserted through the first sleeve, and the first sleeve is crimped to the first end of the extension member.

[0008] Optionally, the valve core opening detection device further includes a fixing bolt, a second nut, and a third nut. The second end of the extension member is connected to the first end of the fixing bolt, and the second end of the fixing bolt is used to pass through the mounting hole on the valve stem stroke fixing bracket. The second nut and the third nut are threadedly connected to the fixing bolt and are respectively arranged on both sides of the valve stem stroke fixing bracket. The second nut and the third nut can jointly clamp the valve stem stroke fixing bracket.

[0009] Optionally, the valve core opening detection device further includes a second sleeve and a fourth nut. The first end of the fixing bolt is inserted through the second sleeve and is threadedly connected to the second sleeve. The fourth nut is threadedly connected to the fixing bolt and abuts against one end of the second sleeve close to the valve stem stroke fixing bracket. The second end of the extension member is connected to the second sleeve.

[0010] Optionally, the second end of the extension member is inserted through the second sleeve, and the second sleeve is crimped to the second end of the extension member.

[0011] Optionally, the extension member is configured as a flexible metal shaft.

[0012] Optionally, the length of the extension member is 100 mm - 200 mm.

[0013] According to a second aspect of the present disclosure, there is provided an oil motor assembly, including an oil motor and the valve core opening detection device as described above. The oil motor includes a regulating valve and a valve stem stroke fixing bracket connected to the valve stem of the regulating valve. The second end of the extension member of the valve core opening detection device is connected to the valve stem stroke fixing bracket.

[0014] According to a third aspect of the present disclosure, there is provided a steam turbine, including the oil motor assembly as described above.

[0015] Through the above technical solution, since the extension direction of the extension piece is the same as that of the feedback rod in the linear displacement sensor, the first end of the extension piece is connected to the feedback rod, the second end of the extension piece is connected to the valve stem stroke fixing bracket connected to the valve stem of the regulating valve, and the extension piece is configured to be able to transfer the displacement of the valve stem fixing bracket in the vertical direction. In other words, the linear displacement sensor can be connected to the valve stem stroke fixing bracket through the extension piece. The distance between the feedback rod and the valve with a higher temperature is relatively far, and the distance between the valve with a higher temperature and other components on the feedback rod and the linear displacement sensor is relatively far. It is not easy for the heat of the valve to be transferred to the linear displacement sensor, effectively avoiding the situation that the linear displacement sensor is affected by high temperature and cannot be used normally.

[0016] For example, when the linear displacement sensor is an LVDT sensor (i.e., a linear variable differential transformer), the sleeve coil of the LVDT sensor is not easily affected by high temperature.

[0017] In addition, since the extension piece is configured to bend when the moving direction of the valve stem stroke fixing bracket forms an angle with the vertical direction, in this way, even during use, if the valve stem stroke fixing bracket and / or the valve stem itself shift, the acting force acting on the extension piece along the inclined direction will cause the extension piece to bend, rather than directly acting on the feedback rod obliquely, effectively avoiding the situation that the feedback rod is subjected to an inclined acting force and breaks, and effectively improving the service life of the feedback rod.

[0018] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. They are used to explain the present disclosure together with the following specific implementation, but do not constitute a limitation to the present disclosure. In the drawings: Figure 1 is a front view schematic diagram of the valve core opening detection device provided by an exemplary embodiment of the present disclosure installed on the oil motor.

[0020] Figure 2 is Figure 1 an enlarged view of A in

[0021] Figure 3 is Figure 1 an enlarged view of B in

[0022] DESCRIPTION OF THE REFERENCE NUMERALS 1 - Linear displacement sensor; 11 - Feedback rod; 2 - Extension piece; 3 - First sleeve; 4 - First nut; 5 - Fixing bolt; 6 - Second nut; 7 - Third nut; 8 - Second sleeve; 9 - Fourth nut; 20 - Oil motor; 21 - Valve stem stroke fixing bracket. Detailed implementation manners

[0023] The following describes in detail the specific implementation manners of the present disclosure with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only for explaining and understanding the present disclosure, and are not used to limit the present disclosure.

[0024] In the present disclosure, it should be understood that the orientation terms such as "upper, lower" and "vertical direction" are defined based on the drawing direction of the accompanying drawings, and are only for facilitating the description of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, as well as a specific orientation structure and operation. Therefore, it should not be construed as a limitation to the present disclosure. The terms "inner, outer" refer to the inside and outside of the corresponding structural contour. In addition, it should be noted that the terms such as "first", "second", etc. are used to distinguish one element from another, and do not have an order and importance. In addition, in the description with reference to the accompanying drawings, the same reference numerals in different drawings represent the same elements.

[0025] In the description of the present disclosure, it should also be noted that unless otherwise clearly specified and limited, the terms "arranged", "connected", "coupled", "installed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0026] As Figures 1 to 3 shown, according to the first aspect of the present disclosure, a valve core opening detection device for a regulating valve of a servomotor 20 of a steam turbine is provided, which includes a linear displacement sensor 1 and an extension member 2. The linear displacement sensor 1 is used to be installed on the servomotor 20. The linear displacement sensor 1 has a feedback rod 11 extending in the vertical direction. The extension member 2 extends in the vertical direction. The first end of the extension member 2 is connected to the feedback rod 11. The second end of the extension member 2 is used to be connected to a valve stem stroke fixing bracket 21 connected to the valve stem of the regulating valve. Wherein, the extension member 2 is configured to be able to transfer the displacement of the valve stem stroke fixing bracket 21 in the vertical direction when the valve stem stroke fixing bracket 21 moves, and bend when the moving direction of the valve stem stroke fixing bracket 21 forms an angle with the vertical direction.

[0027] When the above valve core opening detection device is applied to the regulating valve of the oil servo 20 of a steam turbine, the linear displacement sensor 1 can be installed, for example, on the housing of the oil servo 20. The feedback rod 11 of the linear displacement sensor 1 is connected to the valve rod stroke fixing bracket 21 connected to the valve rod of the regulating valve through an extension member 2. In this way, when the opening of the regulating valve changes, the valve rod stroke fixing bracket 21 can move under the action of the valve rod, thereby driving the extension member 2 and the feedback rod 11 to move. The linear displacement sensor 1 can detect the moving distance of the feedback rod 11, thereby obtaining the moving distance of the valve rod of the regulating valve, and further detecting the change in the opening of the valve core of the regulating valve.

[0028] Here, it should be noted that the present disclosure does not limit the specific type of the above linear displacement sensor 1. The above linear displacement sensor 1 can be any linear displacement sensor 1 suitable for measuring the change in the opening of the oil servo 20. For example, the linear displacement sensor 1 can be an LVDT (Linear Variable Differential Transformer), and the linear displacement sensor 1 can also be an optoelectronic linear displacement sensor 1.

[0029] Through the above technical solution, since the extension directions of the extension member 2 and the feedback rod 11 in the linear displacement sensor 1 are the same, the first end of the extension member 2 is connected to the feedback rod 11, the second end of the extension member 2 is connected to the valve rod stroke fixing bracket 21 connected to the valve rod of the regulating valve, and the extension member 2 is configured to be able to transfer the displacement of the valve rod fixing bracket in the vertical direction. In other words, the linear displacement sensor 1 can be connected to the valve rod stroke fixing bracket 21 through the extension member 2. The distance between the feedback rod 11 and the valve with a higher temperature is relatively far, and the heat of the valve with a higher temperature is not easily transferred to the linear displacement sensor 1, effectively avoiding the situation that the linear displacement sensor 1 cannot be used normally due to the influence of high temperature.

[0030] For example, when the linear displacement sensor 1 is an LVDT sensor, the sleeve coil of the LVDT sensor is not easily affected by high temperature.

[0031] In addition, since the extension member 2 is configured to bend when the moving direction of the valve rod stroke fixing bracket 21 forms an angle with the vertical direction, in this way, even during use, if the valve rod stroke fixing bracket 21 and / or the valve rod shift during movement, the acting force acting on the extension member 2 in the inclined direction will cause the extension member 2 to bend, rather than directly acting on the feedback rod 11 in an inclined manner, effectively avoiding the situation that the feedback rod 11 is subjected to an inclined acting force and causing the feedback rod 11 to break, and effectively improving the service life of the feedback rod 11.

[0032] The present disclosure does not limit the specific connection manner between the feedback rod 11 of the linear displacement sensor 1 and the extension member 2. For example, the feedback rod 11 and the extension member 2 can be fixedly connected (such as by welding) or detachably connected.

[0033] As an implementation manner provided by the present disclosure, as Figure 1 and Figure 2 shown, the above-mentioned valve core opening detection device further includes a first sleeve 3 and a first nut 4. The feedback rod 11 passes through the first sleeve 3 and is threadedly connected to the first sleeve 3. The first nut 4 is threadedly connected to the feedback rod 11 and abuts against one end of the first sleeve 3 close to the linear displacement sensor 1. The first end of the extension member 2 is connected to the first sleeve 3. In other words, the feedback rod 11 is connected to the extension member 2 through the first sleeve 3. The connection between the feedback rod 11 and the extension member 2 is reliable, and it is not easy for the feedback rod 11 and the extension member 2 to become loose. In addition, the feedback rod 11 is detachably connected to the first sleeve 3, and different lengths of the extension member 2 can be replaced according to the actual distance between the valve stem stroke fixing bracket 21 and the feedback rod 11.

[0034] In addition, since the above-mentioned valve core opening detection device further includes a first nut 4, the first nut 4 is threadedly connected to the feedback rod 11 and abuts against one end of the first sleeve 3 close to the linear displacement sensor 1. The first nut 4 can play a role in preventing loosening of the first sleeve 3, effectively avoiding the loosening of the threadedly connected feedback rod 11 and the first sleeve 3, and the situation where the position of the first sleeve 3 on the feedback rod 11 changes, resulting in the measured valve stem movement distance by the linear displacement sensor 1 being different from the actual valve stem movement distance.

[0035] The present disclosure does not limit the connection relationship between the extension member 2 and the first sleeve 3 either, as long as the connection between the extension member 2 and the first sleeve 3 is reliable. For example, the extension member 2 and the first sleeve 3 can be fixedly connected (such as by welding) or detachably connected, etc.

[0036] As an implementation manner provided by the present disclosure, the first end of the above-mentioned extension member 2 passes through the first sleeve 3, and the first sleeve 3 is crimped to the first end of the extension member 2. That is, after inserting the first end of the extension member 2 into the first sleeve 3, the first sleeve 3 is flattened by an external force, so that the first sleeve 3 and the extension member 2 are in interference fit, thereby crimping the first sleeve 3 to the first end of the extension member 2. The connection between the crimped first sleeve 3 and the extension member 2 is reliable, and the installation is simple and convenient, which is beneficial to improving the assembly efficiency of the valve core opening indicating device.

[0037] The present disclosure does not limit the connection relationship between the extension member 2 and the valve stem stroke fixing bracket 21 either. For example, the extension member 2 can be welded to the valve stem stroke fixing bracket 21 or detachably connected to the valve stem stroke fixing bracket 21 through fasteners.

[0038] As an implementation manner provided by the present disclosure, asFigure 1 and Figure 3 As shown in Figure 3 , the spool opening detection device further includes a fixing bolt 5, a second nut 6, and a third nut 7. The second end of the extension piece 2 is connected to the first end of the fixing bolt 5. The second end of the fixing bolt 5 is used to pass through the mounting hole on the valve stem stroke fixing bracket 21. The second nut 6 and the third nut 7 are threadedly connected to the fixing bolt 5 and are respectively arranged on both sides of the valve stem stroke fixing bracket 21. The second nut 6 and the third nut 7 can jointly clamp the valve stem stroke fixing bracket 21. The second nut 6 and the third nut 7 can jointly limit the fixing bolt 5 connected to the extension piece 2, effectively avoiding the situation where the fixing bolt 5 moves in the vertical direction, resulting in different measured valve stem movement distances by the linear displacement sensor 1 and the actual valve stem movement distance.

[0039] The present disclosure does not limit the specific connection relationship between the extension piece 2 and the fixing bolt 5 either, as long as the connection between the extension piece 2 and the fixing bolt 5 is reliable. For example, the extension piece 2 can be welded to the fixing bolt 5.

[0040] As an implementation manner provided by the present disclosure, as Figure 1 and Figure 3 shown in Figure 3 , the spool opening detection device further includes a second sleeve 8 and a fourth nut 9. The first end of the fixing bolt 5 passes through the second sleeve 8 and is threadedly connected to the second sleeve 8. The fourth nut 9 is threadedly connected to the fixing bolt 5 and abuts against one end of the second sleeve 8 close to the valve stem stroke fixing bracket 21. The second end of the extension piece 2 is connected to the second sleeve 8.

[0041] In other words, the extension piece 2 is connected to the fixing bolt 5 through the second sleeve 8. The connection between the extension piece 2 and the fixing bolt 5 is reliable, and there is no relative movement between the extension piece 2 and the fixing bolt 5. Moreover, the connection between the extension piece 2 and the fixing bolt 5 is detachable, which is convenient for replacing the extension piece 2.

[0042] In addition, since the above-mentioned spool opening detection device further includes a fourth nut 9, the fourth nut 9 is threadedly connected to the fixing bolt 5 and abuts against the side of the second sleeve 8 close to the valve stem stroke fixing bracket 21. The fourth nut 9 can play a role in preventing loosening of the second sleeve 8, effectively avoiding the loosening of the threadedly connected fixing bolt 5 and the second sleeve 8, and the change in the position of the second sleeve 8 on the fixing bolt 5, resulting in different measured valve stem movement distances by the linear displacement sensor 1 and the actual valve stem movement distance.

[0043] Here, it should be noted that the present disclosure does not limit the specific connection relationship between the extension piece 2 and the second sleeve 8 either, as long as the connection between the extension piece 2 and the second sleeve 8 is reliable. For example, the extension piece 2 can be welded to the second sleeve 8.

[0044] As an implementation provided by the present disclosure, the second end of the extension member 2 penetrates through the second sleeve 8, and the second sleeve 8 is crimped to the second end of the extension member 2. That is, after the second end of the extension member 2 is inserted into the second sleeve 8, the second sleeve 8 is flattened by an external force, so that the second sleeve 8 and the extension member 2 are in interference fit, thereby enabling the second sleeve 8 to be crimped to the second end of the extension member 2. The connection between the second sleeve 8 and the extension member 2 connected by crimping is reliable, and the installation is simple and convenient, which is beneficial to improving the assembly efficiency of the valve core opening indication device.

[0045] The present disclosure does not limit the specific type of the extension member 2. As an implementation of the present disclosure, the above-mentioned extension member 2 can be configured as a metal flexible shaft. The length of the metal flexible shaft in its axial direction does not change, but it can deform along its radial direction, so as to meet the requirement of transmitting the displacement of the valve stem stroke fixing bracket 21 in the vertical direction when the valve stem stroke fixing bracket 21 moves, and bending when the moving direction of the valve stem stroke fixing bracket 21 forms an angle with the vertical direction.

[0046] As other implementations of the present disclosure, the above-mentioned extension member 2 can also be formed as a universal flexible shaft. The universal flexible shaft has a plurality of shaft bodies that can rotate relative to each other, so as to also meet the requirement of transmitting the displacement of the valve stem stroke fixing bracket 21 in the vertical direction when the valve stem stroke fixing bracket 21 moves, and bending when the moving direction of the valve stem stroke fixing bracket 21 forms an angle with the vertical direction.

[0047] The present disclosure does not limit the length of the extension member 2. As an implementation of the present disclosure, the length of the above-mentioned extension member 2 is 100 mm - 200 mm. The extension member 2 with a length greater than 100 mm can effectively increase the distance between the feedback rod 11 of the linear displacement sensor 1 and the valve with a higher temperature, thereby avoiding the situation that the valve with a higher temperature affects the normal use of the linear displacement sensor 1. And the extension member 2 with a length less than 200 mm can also have a certain rigidity, thereby avoiding the situation that the extension member 2 bends when the valve stem and the valve stem stroke fixing bracket 21 move normally in the vertical direction, and the displacement measured by the linear displacement sensor 1 is different from the actual moving distance of the valve stem.

[0048] According to the second aspect of the present disclosure, an oil motor assembly is provided, which includes an oil motor 20 and the valve core opening detection device as described above. The oil motor 20 includes a regulating valve and a valve stem stroke fixing bracket 21 connected to the valve stem of the regulating valve. The second end of the extension member 2 of the valve core opening detection device is connected to the valve stem stroke fixing bracket 21.

[0049] The valve core opening detection device installed on the oil motor 20 can measure the actual moving distance of the valve stem through the valve stem stroke fixing bracket 21, so as to measure the valve core opening of the regulating valve of the oil motor 20.

[0050] This servomotor assembly has all the beneficial effects of the above-mentioned valve core opening detection device, which will not be elaborated here.

[0051] The present disclosure does not limit the number of valve core opening detection devices used in the above-mentioned servomotor 20. Optionally, as Figure 1 shown, the number of valve core opening detection devices is two, and the two valve core opening detection devices are respectively arranged on both sides of the valve rod stroke fixing bracket 21 of the steam turbine servomotor 20. The two valve core opening detection devices respectively arranged on both sides of the valve rod stroke fixing bracket 21 can simultaneously measure the displacement of the valve rod stroke fixing bracket 21, effectively improving the accuracy of the opening detection of the servomotor 20.

[0052] According to the third aspect of the present disclosure, there is provided a steam turbine including the above-mentioned servomotor assembly.

[0053] This steam turbine has all the beneficial effects of the above-mentioned valve core opening detection device or servomotor assembly, which will not be elaborated here.

[0054] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0055] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0056] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A valve core opening detection device, used for a regulating valve of an oil motor of a steam turbine, characterized in that: include: A linear displacement sensor, used for being installed on the hydraulic motor, wherein the linear displacement sensor has a feedback rod extending in a vertical direction; An extension member extending along the vertical direction, a first end of the extension member being connected to the feedback rod, and a second end of the extension member being used to be connected to a valve stem travel fixing bracket connected to a valve stem of the regulating valve; Wherein, the extension piece is constructed to be able to transmit the displacement of the valve stem stroke fixing bracket in the vertical direction when the valve stem stroke fixing bracket moves, and to bend when the moving direction of the valve stem stroke fixing bracket forms an angle with the vertical direction.

2. The valve core opening detection device according to claim 1, characterized in that: The valve core opening detection device also includes a first sleeve and a first nut. The feedback rod is inserted into the first sleeve and is threadedly connected to the first sleeve. The first nut is threadedly connected to the feedback rod and presses against one end of the first sleeve close to the linear displacement sensor. The first end of the extension piece is connected to the first sleeve.

3. The valve core opening detection device according to claim 2, characterized in that: The first end of the extension piece is inserted into the first sleeve, and the first sleeve is crimped onto the first end of the extension piece.

4. The valve core opening detection device according to claim 1, characterized in that: The valve core opening detection device also includes a fixing bolt, a second nut and a third nut, the second end of the extension piece is connected to the first end of the fixing bolt, and the second end of the fixing bolt is used to pass through the mounting hole on the valve stem stroke fixing bracket; The second nut and the third nut are threadedly connected to the fixing bolt and are respectively arranged on both sides of the valve stem stroke fixing bracket. The second nut and the third nut can clamp the valve stem stroke fixing bracket together.

5. The valve core opening detection device according to claim 4, characterized in that: The valve core opening detection device also includes a second sleeve and a fourth nut. The first end of the fixing bolt is inserted into the second sleeve and is threadedly connected to the second sleeve. The fourth nut is threadedly connected to the fixing bolt and presses against one end of the second sleeve close to the valve stem stroke fixing bracket. The second end of the extension piece is connected to the second sleeve.

6. The valve core opening detection device according to claim 5, characterized in that: The second end of the extension piece is passed through the second sleeve, and the second sleeve is crimped to the second end of the extension piece.

7. The valve core opening detection device according to any one of claims 1 to 6, characterized in that: The extension piece is configured as a metal flexible shaft.

8. The valve core opening detection device according to any one of claims 1 to 6, characterized in that: The length of the extension piece is 100mm-200mm.

9. An oil motor assembly, characterized in that: It comprises an oil motor and a valve core opening detection device according to any one of claims 1 to 8, wherein the oil motor comprises a regulating valve and a valve stem stroke fixing bracket connected to the valve stem of the regulating valve, and the second end of the extension piece of the valve core opening detection device is connected to the valve stem stroke fixing bracket.

10. A steam turbine, characterized in that: Including the oil motor assembly as described in claim 9.

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