Control rod driving device

Abstract

The invention discloses a control rod driving device. The control rod driving device comprises a rack shaft, a lifting driving mechanism, a gripper mechanism, a gripper driving mechanism and a rack shaft position detection mechanism, according to the control rod driving device, the control rod can be grabbed or released by using the grabhook mechanism, and the grabhook driving mechanism is used for driving the grabhook mechanism to perform grabbing and releasing movement, so that the control rod can be automatically grabbed and released. Meanwhile, the lifting driving mechanism is used for driving the rack shaft to do lifting motion, so that the control rod can move up and down in the reactor, hover and release the falling rod in a power-off manner, and starting, power regulation and rapid shutdown of the reactor are realized. And the rack shaft position detection mechanism is arranged, so that the position of the rack shaft in the axial direction is detected, high-precision rack shaft displacement distance measurement can be realized, and high-precision rod position measurement of the real-time position of the control rod is also realized.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactor control rod driving mechanisms, and in particular to a control rod driving device. Background Art

[0002] Reactor miniaturization and increasing reactor power density are the mainstream directions of reactor technology development, including miniaturized modular pressurized water reactors. The compact design of these reactors requires the control rod drive mechanism used to control the reactor power to meet the requirements of large load lifting capacity under small size, remote automatic disconnection and connection of loads, high rod position detection accuracy requirements, and resistance to high temperature space environment. The existing control rod drive mechanism design can no longer meet the use requirements. The new control rod drive mechanism design technology has become a bottleneck in the development of miniaturized reactor technology, and it is urgently needed to develop technology. The existing technology is difficult to meet the technical requirements of the control rod drive mechanism of the reactor miniaturization, which is smaller in size (≤200mm), larger driving load, higher rod position detection accuracy, higher degree of automation, and better high temperature resistance. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a control rod driving device.

[0004] The technical solution adopted by the present invention to solve its technical problem is: construct a control rod driving device, which includes a rack shaft, a lifting driving mechanism connected to the rack shaft and used to drive the rack shaft to perform lifting movement, a gripping mechanism arranged in the rack shaft and capable of performing opening and closing movement along the axial direction of the rack shaft, a gripping driving mechanism used to drive the gripping mechanism to perform lifting movement, and a rack shaft position detection mechanism used to detect the position of the rack shaft, wherein the gripping mechanism is used to grab or release the control rod.

[0005] In some embodiments, the lifting drive mechanism includes a lifting drive motor installed on the circumferential side of the rack shaft, a first coupling connected to the output end of the lifting drive motor, a transmission gear pair connected to the first coupling, a second coupling connected to the transmission gear pair, a reducer connected to the second coupling, a third coupling connected to the reducer, and an electromagnetic clutch connected to the third coupling.

[0006] In some embodiments, the electromagnetic clutch includes a clutch body, a movable toothed disc, a fixed toothed disc and an electromagnet, and the movable toothed disc and the fixed toothed disc can be coupled and separated in a transmission manner under the action of the electromagnet;

[0007] A through hole for the rack shaft to pass through is provided at the center of the clutch body, the movable chainring is coaxially arranged with the fixed chainring, and the movable chainring, the fixed chainring and the electromagnet are all eccentrically arranged with respect to the through hole.

[0008] In some embodiments, the lifting drive mechanism further includes a bevel gear pair connected to the electromagnetic clutch, and the bevel gear pair is meshingly connected to the rack shaft.

[0009] In some embodiments, the rack shaft is provided with a central through hole, and the gripper mechanism is inserted into the central through hole.

[0010] In some embodiments, the gripper drive mechanism includes a gripping motor disposed above the rack shaft, a fourth coupling connected to the output end of the gripping motor, a transmission shaft connected to the fourth coupling, a fifth coupling connected to the transmission shaft, and a push rod connected to the fifth coupling.

[0011] In some embodiments, the gripper driving mechanism further includes a guide assembly, wherein the guide assembly includes a guide sleeve sleeved on the transmission shaft and a plurality of guide wheels;

[0012] The guide sleeve is arranged in the rack shaft and is used to provide a centering and guiding function for the transmission shaft;

[0013] The plurality of guide wheels are arranged at intervals along the circumferential direction of the rack shaft;

[0014] The transmission shaft, the guide sleeve and the rack shaft are coaxially arranged.

[0015] In some embodiments, the control rod drive device further comprises a housing;

[0016] One end of each guide wheel abuts against the outer side surface of the rack shaft, and the other end of each guide wheel abuts against the inner wall surface of the shell. Each guide wheel is also connected to a guide wheel shaft.

[0017] In some embodiments, the guide assembly further includes a plurality of bearings disposed on the circumferential side of the rack shaft.

[0018] In some embodiments, the gripping mechanism includes a transition piece arranged corresponding to the push rod, a pushing piece connected to the transition piece, and two clamping claws connected to the pushing piece, and the two clamping claws are hinged to the pushing piece through a hinge shaft.

[0019] In some embodiments, a first elastic member is connected between the two clamping jaws, and a clamping space for clamping the control rod is formed between the two clamping jaws.

[0020] In some embodiments, the two clamping jaws are axially symmetrical with respect to the axis of the pushing member.

[0021] In some embodiments, the gripping mechanism also includes a second elastic member, the rack shaft includes a accommodating cavity for accommodating the second elastic member, one end of the second elastic member is connected to the bottom end surface of the accommodating cavity, and the other end of the second elastic member is connected to the end surface of the transition member away from the push rod.

[0022] In some embodiments, the rack shaft position detection mechanism includes a magneto-resistance restriction detector and a magnetic block. The magneto-resistance restriction detector is installed at an eccentric position of the rack shaft, and the magnetic block is installed at an upper end of the rack shaft.

[0023] The implementation of the present invention has the following beneficial effects: the control rod drive device can use the gripper mechanism to grab or disengage the control rod, and the gripper drive mechanism drives the gripper mechanism to do the grabbing and disengaging movements, which can realize the automatic grabbing and releasing of the control rod. At the same time, the lifting drive mechanism drives the rack shaft to do the lifting movement, which can make the control rod move up and down in the reactor, hover, and release the rod when the power is cut off to realize the startup, power regulation and rapid shutdown of the reactor. And by setting the rack shaft position detection mechanism, the position of the rack shaft in the axial direction can be detected, which can realize the high-precision rack shaft displacement distance measurement, and also realize the high-precision rod position measurement of the real-time position of the control rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0025] Figure 1 is a schematic diagram of the overall structure of a control rod drive device in some embodiments of the present invention;

[0026] Figure 2 is a schematic diagram of the structure of a guide assembly in some embodiments of the present invention;

[0027] Figure 3 Schematic diagram of the structure of the electromagnetic clutch in some embodiments of the present invention. DETAILED DESCRIPTION

[0028] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0029] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0030] See also Figures 1 to 3 , is a control rod drive device in some embodiments of the present invention, and its main functions are to realize the lifting, lowering, holding of control rods in the core, and emergency rod drop and shutdown functions in case of accidents, etc. The control rod drive device may include a rack shaft 1, a lifting drive mechanism 2 connected to the rack shaft 1 and used to drive the rack shaft 1 to do lifting and lowering movements, a gripper mechanism 3 arranged in the rack shaft 1 and capable of opening and closing movements along the axial direction of the rack shaft 1, a gripper drive mechanism 4 for driving the gripper mechanism 3 to do lifting and lowering movements, and a rack shaft position detection mechanism 5 for detecting the position of the rack shaft 1, and the gripper mechanism 3 is used to grab or release the control rods.

[0031] It can be understood that the control rod drive device can use the gripper mechanism 3 to grab or release the control rod, and use the gripper drive mechanism 4 to drive the gripper mechanism 3 to do the grabbing and releasing movements, which can realize the automatic grabbing and releasing of the control rod. At the same time, the lifting drive mechanism 2 drives the rack shaft 1 to do the lifting movement, which can make the control rod move up and down in the reactor, hover, and release the rod when the power is cut off to realize the startup, power regulation and rapid shutdown of the reactor. And by setting the rack shaft position detection mechanism 5, the axial position of the rack shaft 1 can be detected, which can realize the high-precision displacement distance measurement of the rack shaft 1, and also realize the high-precision rod position measurement of the real-time position of the control rod.

[0032] Specifically, the lifting drive mechanism 2 includes a lifting drive motor 21, a first coupling 22 connected to the output end of the lifting drive motor 21, a transmission gear pair 23 connected to the first coupling 22, a second coupling 24 connected to the transmission gear pair 23, a reducer 25 connected to the second coupling 24, a third coupling 26 connected to the reducer 25, and an electromagnetic clutch 27 connected to the third coupling 26. The lifting drive motor 21 can be a servo motor, the transmission gear pair 23 is a gear pair composed of spur gears, the transmission gear pair 23 rotates along the horizontal direction of the rack shaft 1 under the drive of the lifting drive motor 21, and the reducer 25 is a planetary reducer.

[0033] In addition, the lifting drive motor 21 is installed on the circumferential side of the rack shaft 1, that is, the lifting drive motor 21 is installed in the middle position of the control rod drive device, which can greatly release the upper space of the control rod drive device and realize the miniaturization of the control rod drive device as a whole.

[0034] The electromagnetic clutch 27 includes a clutch body 271, a movable toothed disc 272, a fixed toothed disc 273 and an electromagnet 274. The movable toothed disc 272 and the fixed toothed disc 273 can be connected and separated in a transmission manner under the action of the electromagnet 274. A through hole 2711 for the rack shaft 1 to pass through is provided at the center of the clutch body 271. The movable toothed disc 272 and the fixed toothed disc 273 are coaxially arranged, and the movable toothed disc 272, the fixed toothed disc 273 and the electromagnet 274 are all eccentrically arranged about the through hole 2711. It can be understood that the electromagnetic clutch 27 adopts a hollow structure in the middle. The movable toothed disc 272 and the fixed toothed disc 273 of the electromagnetic clutch 27 are not located at the center of the clutch body 271. The movable toothed disc 272 and the fixed toothed disc 273 can be automatically connected and separated at an eccentric position, which can be applied to eccentric transmission scenarios of the power end, the clutch and the load end, reduce the reversing design, greatly compress the structural design size, improve reliability and reduce the response time of the electromagnetic clutch 27 to engage and open. The electromagnetic clutch 27 can achieve rapid rod drop when the power is cut off and the reactor is shut down quickly.

[0035] In addition, the lifting drive mechanism 2 further includes a bevel gear pair 28 connected to the electromagnetic clutch 27, and the bevel gear pair 28 is meshed and connected with the rack shaft 1. It can be understood that, in combination with Figure 1 , the transmission principle of the lifting drive mechanism 2 is explained: the output end of the lifting drive motor 21 transmits the driving torque to the transmission gear pair 23 through the first coupling 22, and the transmission gear pair 23 then transmits the torque to the reducer 25 through the second coupling 24, the input end of the electromagnetic clutch 27 is connected to the reducer 25, and the input end of the electromagnetic clutch 27 is connected to the bevel gear pair 28, and the bevel gear pair 28 is meshed with the teeth of the rack shaft 1. The cooperation between the bevel gear pair 28 and the rack shaft 1 can convert the direction of the bevel gear pair 28's original rotational movement along the horizontal direction of the rack shaft 1 into the direction of the axial lifting movement of the rack shaft 1. That is, through the forward and reverse rotation of the lifting drive motor 21, the rack shaft 1 can be driven to move up and down, complete the lifting and lowering actions of the control rod, and realize the power regulation of the reactor.

[0036] Furthermore, when the control rod needs to be at a certain fixed height, the motor brake is engaged to achieve the hovering of the control rod. In an emergency condition, the electromagnetic clutch 27 is opened, and under the action of gravity, the rack shaft 1 drives the reducer 25 and the lower half clutch disk of the electromagnetic clutch 27 to rotate together, and the control rod falls, and the shutdown function can be achieved. According to the above description, the lifting drive mechanism 2 of the present invention can achieve the functions of lifting, inserting, hovering and power-off rod dropping of the control rod.

[0037] In some embodiments, the rack shaft 1 is provided with a central through hole, and the gripper mechanism 3 is inserted through the central through hole. Specifically, the gripper drive mechanism 4 includes a gripper motor 42 disposed above the rack shaft 1, a fourth coupling 43 connected to the output end of the gripper motor 42, a transmission shaft 44 connected to the fourth coupling 43, a fifth coupling 45 connected to the transmission shaft 44, and a push rod 46 connected to the fifth coupling 45. Figure 1 The grab motor 42 is located at the top of the entire control rod drive device, and the output end of the grab motor 42 is coaxially arranged with the rack shaft 1. When the grab motor 42 rotates, its torque is sequentially transmitted to the push rod 46 through the fourth coupling 43, the transmission shaft 44, and the fifth coupling 45. The transmission shaft 44 can be a screw shaft. When the grab motor 42 is working, the output end of the grab motor 42 drives the transmission shaft 44 to rotate, so that the push rod 46 can move up and down along the axial direction of the rack shaft 1. The rotational motion of the grab motor 42 is converted into the up and down motion of the push rod 46 through the threaded transmission, which can realize the precise lifting and stopping of the push rod 46.

[0038] In addition, the gripping mechanism 3 includes a transition piece 31 corresponding to the push rod 46, a pushing piece 32 connected to the transition piece 31, and two clamping jaws 33 connected to the pushing piece 32. The two clamping jaws 33 are hinged to the pushing piece 32 through a hinge shaft, and a first elastic piece 34 is connected between the two clamping jaws 33. A clamping space for clamping the control rod is formed between the two clamping jaws 33.

[0039] The two clamping jaws 33 are axially symmetrical with respect to the axis of the pushing member 32. When the clamping jaws 33 are in a grasping state, there is a preset gap between the lower ends of the two clamping jaws 33 for clamping the control rod. When the push rod 46 moves downward, the clamping jaws 33 are in a disengaged state. At this time, the two clamping jaws 33 have a maximum gap under the action of the first elastic member 34 for releasing the control rod, or are prepared for clamping the control rod.

[0040] The gripper mechanism 3 further includes a second elastic member 35, the rack shaft 1 includes a housing cavity 12 for accommodating the second elastic member 35, one end of the second elastic member 35 is connected to the bottom end surface of the housing cavity 12, and the other end of the second elastic member 35 is connected to the end surface of the transition member 31 away from the push rod 46. The second elastic member 35 can be a butterfly spring or a compression spring, and the second elastic member 35 can provide an upward elastic force for the transition member 31 through its elastic action.

[0041] Recombination Figure 1 When the push rod 46 moves downward, the push rod 46 abuts against the transition piece 31 and pushes the transition piece 31 downward. The transition piece 31 drives the push piece 32 and the two clamps 33 to move downward. The two clamps 33 move downward. Under the action of the first elastic member 34, the two clamps 33 disengage to release the control rod or prepare to clamp the control rod. When the push rod 46 moves upward, the push rod 46 no longer acts on the transition piece 31. Under the action of the second elastic member 35, the transition piece 31 rebounds upward to the initial position. At this time, the two clamps 33 move upward, and the distance between the two clamps 33 shrinks to clamp the control rod, which is in a grasping state. Through the arrangement of the above components, the grasping and disengaging of the grasping mechanism can be realized, greatly shortening the material replacement cycle.

[0042] Furthermore, the rack shaft 1 is sealed and connected to the pressure-bearing boundary, the upper and middle parts of the control rod drive device are inert gas space environment, and the gripper mechanism 3 is partially located in the high-temperature coolant medium. It can be understood that the drive motor and its transmission components are placed in a relatively low-temperature gas space, and the gripper mechanism 3 is extended into the high-temperature environment to realize the functions of disengaging and grabbing the control rods, and lifting and inserting the control rods.

[0043] In some embodiments, the gripper drive mechanism 4 further includes a guide assembly 47, the guide assembly 47 includes a guide sleeve 471 sleeved on the transmission shaft 44 and a plurality of guide wheels 473, the guide sleeve 471 is arranged in the rack shaft 1 and is used to provide a centering guide for the transmission shaft 44, the plurality of guide wheels 473 are arranged at intervals along the circumferential direction of the rack shaft 1, and the transmission shaft 44, the guide sleeve 471, and the rack shaft 1 are coaxially arranged. In addition, the control rod drive device further includes a housing 7, one end of each guide wheel 473 abuts against the outer side surface of the rack shaft 1, the other end of each guide wheel 473 abuts against the inner wall surface of the housing 7, and each guide wheel 473 is also connected to a guide wheel shaft 474.

[0044] It can be understood that the guide sleeve 471 can be a copper sleeve guide sleeve, which can play a role in centering and guiding the transmission shaft 44. The outer side of the rack shaft 1 is arranged with a plurality of teeth arranged along the axial direction of the rack shaft 1, and each guide wheel 473 abuts against the teeth. The plurality of guide wheels 473 provide centering and guiding functions for the rack shaft 1, which can greatly reduce the transmission friction resistance. In this embodiment, the number of the guide wheels 473 is three, and in some other embodiments, the number of the guide wheels 473 can also be more than three, which can be set according to actual conditions.

[0045] Furthermore, the guide assembly 47 also includes a plurality of bearings arranged on the circumferential side of the rack shaft 1. Specifically, the bearings can be linear bearings, and the linear bearings are preferably three, which are separately arranged in the upper, middle and lower parts of the rack shaft 1 to support and guide the rack shaft 1 and reduce the resistance of the rack shaft 1 when it moves up and down.

[0046] In some embodiments, the rack shaft position detection mechanism 5 includes a magnetostrictive detector 51 and a magnetic block. The magnetostrictive detector 51 is installed at an eccentric position of the rack shaft 1, and the magnetic block is installed at the upper end of the rack shaft 1. The detection end of the magnetostrictive detector 51 senses the distance from the magnetic block. The magnetostrictive detector 51 is a high-precision ultra-long stroke absolute position measurement sensor manufactured using the magnetostrictive principle, and has the characteristics of high precision, reliable stability, long life, convenient installation, and multiple output modes to choose from. Further, the control rod drive device uses the space released at the top and adopts an eccentrically arranged magnetostrictive detector 51, and the magnetic block is installed at the upper end of the rack shaft 1. The magnetostrictive sensor can accurately detect the position of the magnetic block, and then detect the axial position of the rack shaft 1, which can achieve high-precision rack shaft 1 displacement distance measurement, and also achieve high-precision rod position measurement of the real-time position of the control rod.

[0047] In summary, the beneficial effects of the control rod drive device are:

[0048] 1. The output end of the lifting drive motor 21 and the output end of the grabbing motor 42 are both coaxially arranged with the rack shaft 1, and the reducer 25 and the electromagnetic clutch 27 are both eccentrically arranged, which can greatly reduce the reversing structure and achieve high driving force capacity. At the same time, the lifting drive motor 21 is installed in the middle position of the control rod drive device, which can greatly release the upper space and realize the miniaturization of the control rod drive device as a whole;

[0049] 2. The released upper space adopts an eccentric rack shaft position detection mechanism 5, the magnetic block is placed on the upper end of the rack shaft 1, and the magnetoresistive telescopic detector 51 is arranged outside the rack shaft 1, which can achieve high-precision rod position measurement;

[0050] 3. Both the lifting drive motor 21 and the grabbing motor 42 use servo motors, which can achieve precise positioning, precise speed regulation, etc.;

[0051] 4. A plurality of guide wheels 473 are arranged at intervals along the circumferential direction of the rack shaft 1, one end of each guide wheel 473 abuts against the tooth portion on the outer side of the rack shaft 1, and the other end of each guide wheel 473 abuts against the inner wall surface of the rack shaft 1. This arrangement can provide centering and guiding functions for the rack shaft 1 and the transmission shaft 44, and can greatly reduce the transmission friction resistance;

[0052] 5. The electromagnetic clutch 27 adopts a hollow structure in the middle. The active toothed disc and the fixed toothed disc 273 of the electromagnetic clutch 27 are not located at the center of the clutch body 271. The movable toothed disc 272 and the fixed toothed disc 273 can be automatically connected and separated at an eccentric position, which can be applied to eccentric transmission scenarios of the power end, clutch, and load end, reduce the reversing design, greatly compress the structural design size, improve reliability, and reduce the response time of the electromagnetic clutch 27 to engage and disengage;

[0053] 6. The pressure-bearing boundary of the control rod drive device is divided into three parts. The top stroke section has a small diameter and can release the upper space; the middle part is the motor section, which integrates the lifting drive motor 21 and seals it; the lower part is the transmission section, which has a large internal space and can support and seal the transmission components. The three sections of the pressure-bearing boundary are assembled into one and then installed as a whole, which can realize the segmented installation of components and the overall installation of the mechanism.

[0054] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A control rod drive device, characterized in that: The invention comprises a rack shaft (1), a lifting drive mechanism (2) connected to the rack shaft (1) and used to drive the rack shaft (1) to perform lifting movement, a claw mechanism (3) arranged in the rack shaft (1) and capable of performing opening and closing movement along the axial direction of the rack shaft (1), a claw drive mechanism (4) used to drive the claw mechanism (3) to perform lifting movement, and a rack shaft position detection mechanism (5) used to detect the position of the rack shaft (1), wherein the claw mechanism (3) is used to grasp or release the control rod.

2. The control rod drive device according to claim 1, characterized in that: The lifting drive mechanism (2) comprises a lifting drive motor (21) mounted on the peripheral side of the rack shaft (1), a first coupling (22) connected to the output end of the lifting drive motor (21), a transmission gear pair (23) connected to the first coupling (22), a second coupling (24) connected to the transmission gear pair (23), a reducer (25) connected to the second coupling (24), a third coupling (26) connected to the reducer (25), and an electromagnetic clutch (27) connected to the third coupling (26).

3. The control rod drive device according to claim 2, characterized in that: The electromagnetic clutch (27) comprises a clutch body (271), a movable toothed disc (272), a fixed toothed disc (273) and an electromagnet (274); the movable toothed disc (272) and the fixed toothed disc (273) can be coupled and separated in a transmission manner under the action of the electromagnet (274); A through hole (2711) for the rack shaft (1) to pass through is provided at the center of the clutch body (271), the movable toothed disc (272) and the fixed toothed disc (273) are coaxially arranged, and the movable toothed disc (272), the fixed toothed disc (273) and the electromagnet (274) are all eccentrically arranged with respect to the through hole (2711).

4. The control rod drive device according to claim 2, characterized in that: The lifting drive mechanism (2) further comprises a bevel gear pair (28) connected to the electromagnetic clutch (27), and the bevel gear pair (28) is meshingly connected to the rack shaft (1).

5. The control rod drive device according to claim 4, characterized in that: The rack shaft (1) is provided with a central through hole, and the gripping claw mechanism (3) is inserted into the central through hole.

6. The control rod drive device according to claim 5, characterized in that: The gripper driving mechanism (4) comprises a gripping motor (42) arranged above the rack shaft (1), a fourth coupling (43) connected to the output end of the gripping motor (42), a transmission shaft (44) connected to the fourth coupling (43), a fifth coupling (45) connected to the transmission shaft (44), and a push rod (46) connected to the fifth coupling (45).

7. The control rod drive device according to claim 6, characterized in that: The gripper driving mechanism (4) further comprises a guide assembly (47), wherein the guide assembly (47) comprises a guide sleeve (471) sleeved on the transmission shaft (44) and a plurality of guide wheels (473); The guide sleeve (471) is arranged in the rack shaft (1) and is used to provide a centering and guiding function for the transmission shaft (44); The plurality of guide wheels (473) are arranged at intervals along the circumferential direction of the rack shaft (1); The transmission shaft (44), the guide sleeve (471), and the rack shaft (1) are coaxially arranged.

8. The control rod drive device according to claim 7, characterized in that: The control rod drive device also includes a housing (7); One end of each guide wheel (473) abuts against the outer side surface of the rack shaft (1), and the other end of each guide wheel (473) abuts against the inner wall surface of the shell (7). Each guide wheel (473) is also connected to a guide wheel shaft (474).

9. The control rod drive device according to claim 7, characterized in that: The guide assembly (47) further includes a plurality of bearings arranged on the circumferential side of the rack shaft (1).

10. The control rod drive device according to claim 6, characterized in that: The gripping mechanism (3) comprises a transition piece (31) arranged corresponding to the push rod (46), a pushing piece (32) connected to the transition piece (31), and two clamping claws (33) connected to the pushing piece (32), wherein the two clamping claws (33) are hinged to the pushing piece (32) via a hinge shaft.

11. The control rod drive device according to claim 10, characterized in that: A first elastic member (34) is connected between the two clamping jaws (33), and a clamping space for clamping a control rod is formed between the two clamping jaws (33).

12. The control rod drive device according to claim 10, characterized in that: The two clamping claws (33) are axially symmetrical with respect to the axis of the pushing member (32).

13. The control rod drive device according to claim 10, characterized in that: The gripping mechanism (3) also includes a second elastic member (35), and the rack shaft (1) includes a housing cavity (12) for accommodating the second elastic member (35), one end of the second elastic member (35) is connected to the bottom end surface of the housing cavity (12), and the other end of the second elastic member (35) is connected to the end surface of the transition member (31) away from the push rod (46).

14. The control rod drive device according to claim 6, characterized in that: The rack shaft position detection mechanism (5) comprises a magneto-resistance restriction detector (51) and a magnetic block, wherein the magneto-resistance restriction detector (51) is mounted at an eccentric position of the rack shaft (1), and the magnetic block is mounted at the upper end of the rack shaft (1).

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