Control rod driving mechanism and nested nut assembly

Abstract

The invention discloses a control rod driving mechanism and a nested nut assembly, the nested nut assembly in the scheme comprises a driving piece, the driving piece comprises a driving sleeve and a sliding sleeve, and the sliding sleeve can be driven to move between a first working position and a second working position relative to the driving sleeve in the axial direction of the sliding sleeve. When the sliding sleeve is located at the second working position, one side of the rolling piece is located in the screw rod spiral groove, and the driving piece can control the lead screw to move when rotating. When the sliding sleeve is located at the first working position, the spiral groove in the sliding sleeve is communicated with the spiral hole in the driving sleeve, at the moment, the rolling piece has a space for moving towards the sliding sleeve, one side of the rolling piece can move into the spiral groove in the sliding sleeve, the rolling piece is separated from a lead screw spiral on the lead screw, axial movement of the lead screw is not restrained any more, and the service life of the lead screw is prolonged. Therefore, emergency rod dropping is realized. According to the nested nut assembly, the number of parts in the control rod driving mechanism is greatly reduced, the overall structure of the control rod driving mechanism is simplified, and the nested nut assembly is more suitable for small reactor occasions.

Description

Technical Field

[0001] The present invention relates to the technical field of control rod drive mechanisms of nuclear power reactors, and more particularly to a control rod drive mechanism and a nested nut assembly. Background Art

[0002] In some types of nuclear reactors, such as pressurized water reactors, the rate of nuclear reactions is controlled by the movement of control rods. The control rods include neutron absorbing material and are arranged to be inserted into the reactor core. The deeper the control rods are inserted into the core, the more neutrons are absorbed, and thus the more the nuclear reaction rate is reduced. The amount of insertion of the control rods is therefore controlled, thereby controlling the reactivity of the reactor.

[0003] In an emergency, the control rod needs to be fully inserted into the reactor to quickly stop the nuclear reaction. The control rod drive mechanism types used in the pressurized water reactors (i.e., pressurized water-moderated cooling reactors) currently in operation at home and abroad are mainly divided into three types, namely, rack and pinion type, lead screw roller nut type, and magnetic drive step type. Among them, the lead screw roller nut type is to control the axial movement of the lead screw by driving the nut through the cooperation of the lead screw, roller and nut, thereby controlling the insertion amount of the control rod into the reactor.

[0004] For example, the publication number CN105788668A discloses a control rod drive mechanism with a detachable nut drive, including a detachable nut component; the detachable nut component is composed of a detachable nut, a plurality of connecting rods, an armature, and a release spring and is sleeved in the motor pressure housing; wherein the two connecting rods are identical; the two identical connecting rods, a connecting rod for connecting the rotor sleeve, the armature and the detachable nut constitute a single-degree-of-freedom connecting rod mechanism with a parallelogram structure, and the position of the detachable nut is controlled by the up and down movement of the armature; the driving screw component is composed of a core rod, a driving screw, a positioning block, a rod drop spring and a guide block; wherein one end of the driving screw is connected to the control rod assembly. In this scheme, the detachable nut is used to rotate the driving screw to make a linear motion, so as to realize the insertion, extraction and position keeping functions of the control rod assembly under various working conditions of the reactor. When an emergency safety situation causes a power outage, the drive screw cannot move. The armature is then ejected and the armature pulls the detachable nut through the connecting rod, disengaging it from the drive screw. The drive screw then quickly pushes the control rod assembly into the core under the action of the rod drop spring.

[0005] However, in this solution, in an emergency, the nut can be separated by pulling the connecting rod to disengage it from the meshing state with the drive screw, thereby achieving rod drop. The connecting rod mechanism controls the nut to separate. On the one hand, the connecting rod mechanism has many degrees of freedom, and after long-term operation, the connecting rod structure will wear and become loose, making it impossible to accurately control the opening and closing position of the nut. In addition, there are many components and connection positions in the connecting rod structure, while the nut drive structure is relatively small in a small reactor. It is difficult to accurately arrange the various components in this space. In addition, after the connecting rod controls the nut to close, the connecting rod structure has poor self-locking properties for the nut. If a large axial force is applied to the screw, it is easy to cause the nut to open and the screw to fall out. Summary of the invention

[0006] This solution provides a control rod drive mechanism and a nested nut assembly, which greatly simplifies the structure of the control rod drive mechanism and can drop the rod in an emergency.

[0007] In order to achieve the above object, the technical solution provided by the present invention is:

[0008] A nested nut assembly comprising:

[0009] A driving member, used for connecting with a screw rod with a spiral screw thread groove on the outside;

[0010] The driving member comprises:

[0011] A driving sleeve, which is used to be sleeved on the outer side of the screw rod, and a screw hole is provided on the driving sleeve, and a movable rolling element is arranged in the screw hole;

[0012] A sliding sleeve, which is sleeved on the outer side of the driving sleeve and has a spiral groove on the inner side;

[0013] The sleeve can be driven to move between a first working position and a second working position relative to the drive sleeve along its axial direction; when the drive member is cooperatively connected with the lead screw, when the sleeve moves to the first working position, the helical hole is communicated with the helical groove, and when the lead screw is subjected to axial force, it will push the rolling member, so that part of the rolling member can move into the helical groove along the radial direction of the drive member, and the rolling member is disengaged from the helical groove of the lead screw; when the sleeve moves to the second working position, the inner surface of the sleeve drives the rolling member to disengage from the helical groove, and the rolling member moves and part of it passes through the helical hole and can be inserted into the helical groove of the lead screw.

[0014] In this solution, the nested nut assembly includes a driving member, and the driving member includes a driving sleeve and a sliding sleeve. The sliding sleeve can be driven to move between a first working position and a second working position along its axial direction relative to the driving sleeve. The position of the rolling member is controlled by the sliding sleeve being located at different positions. The rolling member is located at different positions to correspond to the normal operation of the lead screw and the emergency rod drop of the lead screw. Specifically, when the sliding sleeve is located at the second working position, when one side of the rolling member is located in the screw spiral groove, the lead screw operates normally, and the movement of the lead screw can be controlled when the driving member rotates. When the sliding sleeve is located at the first working position, the spiral groove on the sliding sleeve is connected to the spiral hole on the driving sleeve. At this time, the rolling member has space to move toward the sliding sleeve, and one side of the rolling member can move into the spiral groove on the sliding sleeve. The rolling member is separated from the lead screw spiral on the lead screw and no longer constrains the axial movement of the lead screw, thereby achieving emergency rod drop. The nested nut structure mainly includes a drive sleeve and a sliding sleeve. The sliding sleeve is moved to different positions to control the position of the rolling element, which greatly reduces the number of parts in the control rod drive mechanism, simplifies the overall structure of the control rod drive mechanism, and is more suitable for small reactors. In addition, the drive sleeve and the sliding sleeve are both in an integral cylindrical shape, the drive sleeve is arranged on the outside of the lead screw, and the sliding sleeve is arranged on the outside of the drive sleeve. In the radial direction of the lead screw, the drive sleeve and the sliding sleeve have no displacement change, so that the self-locking property of the nested nut is better.

[0015] As a further improvement, the driving member further comprises an electromagnetic coil, and the electromagnetic coil is arranged close to the driving member; one end of the driving sleeve is connected to the first armature, and one end of the sliding sleeve is connected to the second armature;

[0016] When the electromagnetic coil is powered on, the first armature and the second armature are attracted, and the sliding sleeve moves to the second working position; when the electromagnetic coil is powered off, the first armature and the second armature are disconnected, and the sliding sleeve moves to the first working position.

[0017] As a preferred implementation, an elastic member is connected between the drive sleeve and the sliding sleeve along the axial direction thereof.

[0018] As another preferred embodiment, it further comprises a limiting member, which is fixedly arranged relative to the driving sleeve, and when the sliding sleeve moves to the first working position, the limiting member limits the sliding sleeve.

[0019] In one embodiment, one end of the spiral hole close to the inner surface of the driving sleeve is the second end, and the opening size of the second end of the spiral hole is smaller than the diameter size of the rolling element.

[0020] As a further improvement, the sliding sleeve is further connected to a guide rod, and the guide rod is fixedly arranged relative to the driving sleeve.

[0021] As a further improvement, one side of the guide rod is embedded in the drive sleeve, and the other side is embedded in the sliding sleeve.

[0022] As an embodiment, the spiral hole includes a spiral portion, and the spiral portion is arranged continuously or discontinuously.

[0023] The present invention also provides a control rod driving structure to control the insertion amount of the control rod into the core stack, comprising the nested nut and the lead screw,

[0024] A spiral screw thread groove is provided on the outer side of the screw rod; the screw rod is inserted into the driving sleeve and arranged axially along the driving sleeve, and when the driving member rotates, the screw rod can be driven to move along its axial direction;

[0025] When the sleeve moves to the first working position, the helical hole is connected to the helical groove, and when the lead screw is subjected to axial force, it will push the rolling element, so that part of the rolling element can move into the helical groove along the radial direction of the driving element, and the rolling element is disengaged from the helical groove of the lead screw; when the sleeve moves to the second working position, the inner surface of the sleeve drives the rolling element to disengage from the helical groove, and the rolling element moves and part of it can be stuck in the helical groove of the lead screw after passing through the helical hole.

[0026] In this solution, the nested nut and the lead screw described in the control rod drive structure, the nested nut includes a driving member, the driving member includes a driving sleeve and a sliding sleeve, the driving sleeve and the lead screw are connected to each other, and the position of the rolling member is controlled by the sliding sleeve being located at different positions to correspond to the normal operation of the lead screw and the emergency rod drop of the lead screw. The control rod drive structure also has the beneficial effects of the other nested nuts.

[0027] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0028] (1) In a nested nut assembly of the present invention, the driving member further includes an electromagnetic coil, which is sleeved on the outside of the driving member. One end of the driving sleeve is connected to the first armature, and one end of the sliding sleeve is connected to the second armature. By turning the electromagnetic coil on and off, the first armature and the second armature are controlled to be attracted or not, thereby correspondingly controlling the different positions of the sliding sleeve, thereby simplifying the drive setting method for the movement of the sliding sleeve.

[0029] (2) In a nested nut assembly of the present invention, an elastic member is connected between the drive sleeve and the sliding sleeve along the axial direction thereof. When the power is cut off in an emergency, the elastic member also exerts an elastic force on the sliding sleeve, and under the elastic force and the weight of the sliding sleeve itself, the sliding sleeve can be quickly moved to the first working position, thereby responding to the emergency rod drop in a timely manner.

[0030] (3) A nested nut assembly of the present invention, wherein the nested nut further comprises a limit member, which is fixedly arranged relative to the driving sleeve. When the sliding sleeve moves to the first working position, the limit member limits the sliding sleeve, thereby accurately positioning the first working position of the sliding sleeve, so that the spiral hole and the spiral groove can be accurately matched.

[0031] (4) A nested nut assembly of the present invention is further provided with a guide rod, one side of which is embedded in the driving sleeve, and the other side of which is embedded in the sliding sleeve, so that the guide rod can guide the movement of the sliding sleeve relative to the driving sleeve in the axial direction on the one hand, and limit the position between the sliding sleeve and the driving sleeve in the circumferential direction on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the front view of the control rod drive mechanism;

[0033] Figure 2 is a cross-sectional view of the control rod drive mechanism;

[0034] Figure 3 for Figure 2 A magnified schematic diagram of the structure at B in the middle;

[0035] Figure 4 It is a three-dimensional cross-sectional view of the matching connection structure of the driving sleeve and the sliding sleeve;

[0036] Figure 5 for Figure 2 A magnified schematic diagram of the structure at C in the middle;

[0037] Figure 6 It is a three-dimensional diagram of the matching connection structure of the driving sleeve and the sliding sleeve;

[0038] Figure 7 It is a three-dimensional diagram of the separate structure of the driving sleeve and the sliding sleeve;

[0039] Figure 8 This is a three-dimensional view from another angle of the separate structure of the drive sleeve and the sliding sleeve.

[0040] Description of labels:

[0041] 1. Screw rod; 11. Screw rod spiral groove;

[0042] 2. Shell;

[0043] 3. Electromagnetic coil;

[0044] 4. driving sleeve; 41. first armature; 42. thread hole; 421. first end; 422. second end; 43. rolling element; 44. guide rod;

[0045] 5. Sliding sleeve; 51. Second armature; 52. Screw groove; 53. Limiting member;

[0046] 6. Elastic parts;

[0047] 7. Driving sleeve driving connection end;

[0048] 8. Rotate the bearing. DETAILED DESCRIPTION

[0049] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments.

[0050] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0051] At the same time, the terms such as "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like cited in this specification are only for the convenience of description, and are not used to limit the scope of implementation. The change or adjustment of their relative relationship shall be regarded as the scope of implementation of the present invention without substantial change of technical content. Moreover, in addition to being used to indicate orientation or position relationship, some of the above terms may also be used to express other meanings. For example, the term "upper" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances.

[0052] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so as to describe the embodiments of the present application described herein.

[0053] like Figure 1 and Figure 2 As shown, the present invention provides a control rod drive structure, which is applied to a nuclear reactor to control the insertion amount of the control rod into the core. The drive structure controls the insertion amount of the control rod into the core. The deeper the control rod is inserted into the core, the more neutrons are absorbed, and thus the nuclear reaction rate is reduced. In an emergency, the control structure also needs to perform an emergency rod drop on the control rod so that the control rod is fully inserted into the core.

[0054] like Figure 3 and Figure 4As shown, the present invention also provides a nested nut assembly, including a driving member, which is used to cooperate with the screw rod 1. When the driving member rotates, it is used to control the screw rod 1 to move along its axial direction.

[0055] Specifically, the screw rod 1 is arranged vertically, and a spiral screw rod spiral groove 11 is provided on the outer side of the screw rod 1. The screw rod spiral groove 11 is arranged continuously.

[0056] The driving member includes a driving sleeve 4 and a sliding sleeve 5. The driving sleeve 4 is used to be sleeved on the outside of the screw rod 1. A spiral hole 42 is provided on the driving sleeve 4, and the spiral hole 42 is provided through the side wall of the driving sleeve 4. It should be noted that the spiral hole 42 includes a spiral portion, and the position at which it is provided can correspond to the spiral groove 11 of the screw rod. In addition, in the present embodiment, the spiral hole 42 is provided continuously; however, in other embodiments, the spiral hole 42 may also be provided intermittently, and each intermittent length of the spiral hole 42 may be the same or different. A movable rolling member 43 is provided in the spiral hole 42. Preferably, the rolling member 43 is spherical and can be moved flexibly.

[0057] The sliding sleeve 5 is sleeved on the outer side of the driving sleeve 4, and a spiral groove 52 is provided on the inner side of the sliding sleeve 5. Similarly, the spiral groove 52 is spiral-shaped, and the spiral groove 52 can be continuous or discontinuous. The setting orientation of the spiral groove 52 needs to correspond to the setting of the spiral hole 42. It should be noted that when the spiral hole 42 is set to be continuous, the spiral groove 52 is also continuous; when the spiral hole 42 is set to be discontinuous, the spiral groove 52 can be continuous or discontinuous. When the spiral groove 52 and the spiral hole 42 are both discontinuous, the position and length of each discontinuity of the spiral groove 52 need to correspond to the position and length of each discontinuity of the spiral hole 42.

[0058] Specifically, in the axial direction of the screw 1, the drive sleeve 4 is fixedly arranged; in the circumferential direction, the drive sleeve 4 only rotates around the screw 1. The sleeve 5 can be driven and move between the first working position and the second working position relative to the drive sleeve 4 along its axial direction. When the drive member is connected with the screw 1, when the sleeve 5 moves to the first working position, the spiral hole 42 is connected with the spiral groove 52, and when the screw 1 is subjected to an axial force, it will push the rolling member 43, so that part of the rolling member 43 can move into the spiral groove 52 along the radial direction of the drive member, and the rolling member 43 is separated from the screw spiral groove 11; when the sleeve 5 moves to the second working position, the inner surface of the sleeve 5 drives the rolling member 43 to separate from the spiral groove 52, and the rolling member 43 moves and its part can be stuck in the screw spiral groove 11 after passing through the spiral hole 42. It should be noted that the axial force on the screw 1 can be its own weight or other. In this embodiment, the axial force on the screw 1 is explained as its own weight.

[0059] like Figure 5As shown, for the sake of ease of explanation and understanding, the description is based on the state in which the driving member is connected with the screw rod 1. Figure 3 The view orientation in Figure 5 shown. Figure 3 The side of a certain component close to the center line of the screw rod 1 is the "inside", and the side away from the center line of the screw rod 1 is the "outside". When the sleeve 5 moves to the first working position, the positions of the spiral hole 42 and the spiral groove 52 correspond to each other, and the outer side of the spiral hole 42 and the inner side of the spiral groove 52 are matched and connected with each other. At this time, the screw rod 1 can fall under its own gravity. During the falling process, the outer surface of the screw rod 1 pushes a part of the outer side of the rolling element 43 into the spiral groove 52, and the rolling element 43 is separated from the screw rod spiral groove 11. When the sleeve 5 moves to the second working position, in the process of the sleeve 5 moving to the second working position, the spiral hole 42 and the spiral groove 52 tend to stagger with each other, and the inner surface of the sleeve 5 drives the rolling element 43 to disengage from the spiral groove 52, and the driving element rotates at the same time during the process. When the inner side of the spiral hole 42 and the outer side of the screw rod spiral groove 11 are matched and connected with each other during rotation, the spiral hole 42 and the spiral groove 52 are completely staggered, the rolling element 43 moves and a part of the inner side of the rolling element 43 passes through the spiral hole 42 and then is inserted into the screw rod spiral groove 11, forming a driven structure of the ball screw, and when the driving element rotates, the screw rod 1 is driven to move along its axial direction.

[0060] Recombination Figure 3 As shown, the driving member also includes an electromagnetic coil 3, which is arranged near the driving member. One end of the driving sleeve 4 is connected to the first armature 41, and one end of the sliding sleeve 5 is connected to the second armature 51. When the electromagnetic coil 3 is powered on, the first armature 41 and the second armature 51 located in the electromagnetic coil 3 are magnetized, and the first armature 41 and the second armature 51 are attracted to each other. Since the driving sleeve 4 is fixed in the axial direction of the screw rod 1, the second armature 51 is fixedly arranged on the sliding sleeve 5, and the second armature 51 is attracted toward the first armature 41, driving the sliding sleeve 5 to move to the second working position. In an emergency, when the electromagnetic coil 3 is powered off, the first armature 41 and the second armature 51 are no longer attracted, the first armature 41 and the second armature 51 are disconnected, and the sliding sleeve 5 falls and moves to the first working position. In this embodiment, the method of driving the second armature 51 and the first armature 41 to attract each other is realized by the electromagnetic coil 3, so that the overall structure is more simplified. However, in other embodiments, the driving method of the first armature 41 and the second armature 51 to attract each other can also be set to other.

[0061] Regarding the arrangement of the electromagnetic coil 3, the electromagnetic coil 3 can be sleeved outside the driving member. In other cases, the electromagnetic coil 3 can also be arranged above or below the armature.

[0062] Combination Figure 6 , Figure 7 and Figure 8As shown, the first armature 41 is fixedly connected to the drive sleeve 4, specifically by bolts or screws. The second armature 51 is fixedly connected to the sliding sleeve 5, and can also be fixed by bolts or screws. In other cases, the first armature 41 and the drive sleeve 4, and the second armature 51 and the sliding sleeve 5 can also be fixed by other means, such as gluing or snap-fitting.

[0063] As a preferred embodiment, an elastic member 6 is connected between the drive sleeve 4 and the sliding sleeve 5 along the axial direction thereof. During operation, the first armature 41 and the second armature 51 are attracted to each other, and the elastic member 6 is squeezed. When the electromagnetic coil 3 is powered off in an emergency, in order to quickly move the sliding sleeve 5 to the first working position, the positions of the spiral hole 42 and the spiral groove 52 correspond to each other, and when the sliding sleeve 5 falls under its own weight, the elastic member 6 simultaneously applies an elastic force to the sliding sleeve 5, so that the sliding sleeve 5 quickly moves to the first working position. However, in some other cases, the elastic member 6 may not be provided, and the sliding sleeve 5 falls under its own weight.

[0064] Combination Figure 4 and Figure 8 As shown, the nested nut further includes a stopper 53, which is fixedly arranged relative to the drive sleeve 4. In a specific case, the stopper 53 is a baffle, and a slot is provided on the outer side of the drive sleeve 4, and the stopper 53 is installed in the slot. When the sliding sleeve 5 moves to the first working position, the stopper 53 limits the sliding sleeve 5, thereby accurately positioning the first working position of the sliding sleeve 5, so that the spiral hole 42 and the spiral groove 52 can accurately match.

[0065] Combination Figure 3 and Figure 7 As shown, in order to avoid the misalignment between the sliding sleeve 5 and the driving sleeve 4 in the circumferential direction during the movement of the sliding sleeve 5 relative to the driving sleeve 4, a guide rod 44 is further connected to the sliding sleeve 5. Preferably, the guide rod 44 is fixedly arranged relative to the driving sleeve 4. More preferably, one side of the guide rod 44 is embedded in the driving sleeve 4, and the other side is embedded in the sliding sleeve 5. This arrangement of the guide rod 44 enables the guide rod 44 to guide the movement of the sliding sleeve 5 relative to the driving sleeve 4 in the axial direction on the one hand, and to limit the position between the sliding sleeve 5 and the driving sleeve 4 in the circumferential direction on the other hand.

[0066] As a specific implementation, one end of the spiral hole 42 close to the inner surface of the driving sleeve 4 is the second end 422 , and the opening size of the second end 422 of the spiral hole 42 is smaller than the diameter of the rolling element 43 to prevent the rolling element 43 from falling off from the spiral hole 42 .

[0067] Recombination Figure 3As shown, the outer side of the drive sleeve 4 is also sleeved with a rotating bearing 8. Specifically, the upper end of the drive sleeve 4 has a drive sleeve driving connection end 7, and the rotating bearing 8 is sleeved on the drive sleeve driving connection end 7. The inner ring of the rotating bearing 8 is relatively fixed to the drive sleeve driving connection end 7. In one case, the drive sleeve driving connection end 7 is integrally formed with other parts of the drive sleeve 4; in other cases, the drive sleeve driving connection end 7 can also be separately provided with other parts of the drive sleeve 4 and fixedly connected by bolts or screws.

[0068] In order to protect the nested nut, a housing 2 is further provided. Specifically, the housing 2 is sleeved on the outside of the electromagnetic coil 3.

[0069] Combination Figure 1 , Figure 2 and Figure 3 As shown, a control rod driving structure provided by the present invention comprises the nested nut and the screw 1. A spiral screw thread groove 11 is provided on the outer side of the screw 1; the screw 1 is inserted into the driving sleeve 4 and arranged axially along the driving sleeve 4, and the screw 1 can be driven to move along its axial direction when the driving member rotates.

[0070] In one case, a motor can be used to drive the driving member to rotate. Specifically, a gear is fixedly connected to the outer side of the outer ring of the rotating bearing 8, and the gear is drivingly connected to the output shaft of the motor, so that the motor can drive the driving member to rotate.

[0071] Specifically, in an emergency, after power failure, the sleeve 5 moves to the first working position, the spiral hole 42 corresponds to the spiral groove 52, and the spiral hole 42 is connected to the spiral groove 52. At this time, the screw rod 1 can fall under its own gravity. During the falling process, the outer surface of the screw rod 1 pushes a part of the outer side of the rolling element 43 into the spiral groove 52, and the rolling element 43 is disengaged from the screw rod spiral groove 11. At the same time, the control rod is urgently dropped into the core along with the screw rod 1. During normal operation, the sleeve 5 moves to the second working position. In the process of the sleeve 5 moving to the second working position, the helical hole 42 and the helical groove 52 tend to be offset from each other, and the inner surface of the sleeve 5 drives the rolling element 43 to disengage from the helical groove 52. In the process, the driving element rotates at the same time. When the helical hole 42 is connected to the screw rod helical groove 11 during rotation, the helical hole 42 and the helical groove 52 are completely offset, and the rolling element 43 moves and a part of the inner side of the rolling element 43 passes through the helical hole 42 and then is inserted into the screw rod helical groove 11, forming a driven structure of the ball screw. When the driving element rotates, the screw rod 1 is driven to move along its axial direction to control the insertion amount of the control rod into the core stack.

[0072] The terms "installed", "set", "provided with", and "connected" referred to herein should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0073] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A nested nut assembly, characterized in that: include, A driving member, used for being connected in cooperation with a screw (1) having a spiral screw thread groove (11) formed on the outer side; The driving member comprises: A driving sleeve (4) is used for being sleeved on the outer side of the screw rod (1), and a screw hole (42) is provided on the driving sleeve, and a movable rolling element (43) is arranged in the screw hole (42); A sliding sleeve (5) is sleeved on the outer side of the driving sleeve (4) and has a spiral groove (52) formed on the inner side thereof; The sleeve (5) can be driven to move relative to the drive sleeve (4) along its axial direction between a first working position and a second working position; when the drive member is connected with the screw (1), when the sleeve (5) moves to the first working position, the spiral hole (42) is connected to the spiral groove (52), and when the screw (1) is subjected to an axial force, it pushes the rolling member (43), so that part of the rolling member (43) can move along the radial direction of the drive member into the spiral groove (52), and the rolling member (43) is disengaged from the screw spiral groove (11); when the sleeve (5) moves to the second working position, the inner surface of the sleeve (5) drives the rolling member (43) to disengage from the spiral groove (52), and the rolling member (43) moves and a part of it passes through the spiral hole (42) and can be inserted into the screw spiral groove (11).

2. The nested nut assembly according to claim 1, characterized in that: The driving member further comprises an electromagnetic coil (3), and the electromagnetic coil (3) is arranged close to the driving member; one end of the driving sleeve (4) is connected to a first armature (41), and one end of the sliding sleeve (5) is connected to a second armature (51); When the electromagnetic coil (3) is powered on, the first armature (41) and the second armature (51) are attracted, and the sliding sleeve (5) moves to the second working position; when the electromagnetic coil (3) is powered off, the first armature (41) and the second armature (51) are disconnected, and the sliding sleeve (5) moves to the first working position.

3. The nested nut assembly according to claim 2, characterized in that: An elastic member (6) is connected between the driving sleeve (4) and the sliding sleeve (5) along their axial direction.

4. The nested nut assembly according to claim 2, characterized in that: It also comprises a limiting member (53), wherein the limiting member (53) is fixedly arranged relative to the driving sleeve (4), and when the sliding sleeve (5) moves to the first working position, the limiting member (53) limits the sliding sleeve (5).

5. The nested nut assembly according to any one of claims 1 to 4, characterized in that: One end of the spiral hole (42) close to the inner surface of the driving sleeve (4) is a second end (422), and the opening size of the second end (422) of the spiral hole (42) is smaller than the diameter size of the rolling element (43).

6. The nested nut assembly according to claim 5, characterized in that: The sliding sleeve (5) is also connected to a guide rod (44), and the guide rod (44) is fixedly arranged relative to the driving sleeve (4).

7. The nested nut assembly according to claim 6, characterized in that: One side of the guide rod (44) is embedded in the drive sleeve (4), and the other side is embedded in the slide sleeve (5).

8. The nested nut assembly according to claim 5, characterized in that: The spiral hole (42) includes a spiral portion, and the spiral portion is arranged continuously or discontinuously.

9. A control rod drive structure for controlling the insertion amount of the control rod into the core stack, characterized in that: comprising a nested nut assembly and a screw rod (1) as claimed in any one of claims 1 to 8, A spiral screw thread groove (11) is provided on the outer side of the screw rod (1); the screw rod (1) is inserted into the drive sleeve (4) and is arranged axially along the drive sleeve (4); when the drive member rotates, the screw rod (1) can be driven to move along its axial direction; When the sleeve (5) moves to the first working position, the helical hole (42) is connected to the helical groove (52), and when the lead screw (1) is subjected to axial force, it will push the rolling element (43), so that part of the rolling element (43) can move into the helical groove (52) along the radial direction of the driving element, and the rolling element (43) is disengaged from the lead screw helical groove (11); when the sleeve (5) moves to the second working position, the inner surface of the sleeve (5) drives the rolling element (43) to disengage from the helical groove (52), and the rolling element (43) moves and part of it passes through the helical hole (42) and can be inserted into the lead screw helical groove (11).

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