Stepping motor and control rod drive system

Abstract

This invention relates to the field of nuclear power, providing a stepper motor and control rod drive system. The stepper motor includes: a drive piston assembly that reciprocates to drive a drive wheel for forward or reverse stepping; the drive wheel includes a first meshing tooth; and a self-locking mechanism including a second meshing tooth. In a self-locked state, the second meshing tooth meshes with the first meshing tooth; in a free state, the second meshing tooth disengages from the first meshing tooth, and the output shaft is connected to the drive wheel. This invention addresses the shortcomings of commonly used stepper motors in reactors, such as large size, low reliability, and high cost. The stepper motor provided by this invention achieves rotational stepping of the output shaft by driving the drive wheel to rotate in both directions through the reciprocating motion of the drive piston assembly; and switches between the self-locked and free states of the output shaft through the engagement and disengagement of the first and second meshing teeth, thereby reducing the size of the stepper motor, improving stepping reliability, reducing cost, and meeting the requirements of reactor operation.

Description

Technical Field

[0001] This invention relates to the field of nuclear power technology, and in particular to a stepper motor and control rod drive system. Background Technology

[0002] A stepper motor is another name used in the industry for a "stepping motor." Existing stepper motors are open-loop control elements that convert electrical pulse signals into angular displacement or linear force. When a stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (called the "step angle") in a set direction. Its rotation occurs step by step at fixed angles.

[0003] Absorber drum control rods are commonly used in space reactors, research reactors, and high-flux reactors. Control rods are the primary means of controlling reactivity in nuclear reactors, and their movement within the reactor dictates the different drive mechanisms that are matched to them. Linearly moving control rods require linear motion drive mechanisms, while rotating control rods require rotating drive mechanisms, such as stepper motors. Because nuclear reactors are massive radiation sources, existing stepper motor drive systems are bulky, have low reliability, and are costly. Summary of the Invention

[0004] This invention provides a stepper motor and control rod drive system to address the shortcomings of commonly used stepper motors in reactors, such as large size, low reliability, and high cost. The reciprocating motion drive piston assembly drives the drive wheel to achieve stepping, reducing the size. The meshing of the first and second meshing teeth improves the reliability of stepping and reduces costs.

[0005] This invention provides a stepper motor, comprising:

[0006] A stepping mechanism, comprising a drive piston assembly and a drive wheel, wherein the drive piston assembly reciprocates to drive the drive wheel to step forward or backward, and the drive wheel includes a first meshing tooth;

[0007] The self-locking mechanism switches between a self-locking state and a free state. The self-locking mechanism includes a second meshing tooth. In the self-locking state, the second meshing tooth meshes with the first meshing tooth. In the free state, the second meshing tooth disengages from the first meshing tooth.

[0008] An output shaft passes through the self-locking mechanism and is connected to the drive wheel.

[0009] According to the stepper motor provided by the present invention, the drive piston assembly includes a first set of drive members and a second set of drive members, wherein the first set of drive members and the second set of drive members are not equidistant from the output shaft.

[0010] According to the stepper motor provided by the present invention, the drive wheel includes a first oblique hole and a second oblique hole, the first oblique hole is formed at equal intervals to form a first circle with the output shaft as the center, the second oblique hole is formed at equal intervals to form a second circle with the output shaft as the center, and the diameter of the first circle and the diameter of the second circle are not equal;

[0011] The first set of driving components mates with the first oblique hole, and the second set of driving components mates with the second oblique hole. The first oblique hole and the second oblique hole have opposite inclination directions.

[0012] According to the stepper motor provided by the present invention, the first set of driving members includes at least two, each of the first set of driving members cooperating with the first oblique hole and working alternately.

[0013] According to the stepper motor provided by the present invention, the first set of driving components and the second set of driving components have the same structure, including a piston guide tube, a driving piston, a first spring and a push rod. The piston guide tube drives the driving piston to move towards the driving wheel through a driving medium. The first spring is used to reset the driving piston. The push rod is connected to the driving piston and is used to push the driving wheel to rotate.

[0014] According to the stepper motor provided by the present invention, the driving medium in the piston lead tube is gas or liquid.

[0015] According to the stepper motor provided by the present invention, the self-locking mechanism further includes a self-locking positioning cylinder, a second spring, and a clutch assembly. The second engagement tooth is disposed on the self-locking positioning cylinder, and the second spring is disposed between the self-locking positioning cylinder and the clutch assembly. The clutch assembly is used to switch between the self-locking state and the free state.

[0016] According to the stepper motor provided by the present invention, the clutch assembly includes a clutch disc, a piston assembly, and a clutch lead tube. The clutch disc and the self-locking cylinder are connected to the piston assembly. A second spring is provided between the clutch disc and the self-locking cylinder. The clutch lead tube is used to push the piston assembly.

[0017] In the self-locking state, the clutch lead tube introduces clutch medium into the piston assembly, causing the piston assembly to push the clutch disc and self-locking cylinder upward; in the free state, the piston assembly drives the clutch disc and self-locking cylinder downward.

[0018] According to the stepper motor provided by the present invention, the piston assembly includes a clutch piston, a third spring and a sealing member, wherein the third spring is disposed between the sealing member and the clutch piston;

[0019] In the self-locking state, the clutch piston compresses the third spring, causing the sealing member to press against the clutch disc; in the free state, the third spring resets the clutch piston, creating a gap between the clutch piston and the sealing member.

[0020] The present invention also provides a control rod driving system, including the stepper motor described above.

[0021] The stepper motor provided by this invention drives the drive wheel to rotate in both directions by the reciprocating motion of the drive piston assembly, thereby realizing the rotational stepping of the output shaft; the self-locking state and free state of the output shaft are switched by the engagement and disengagement of the first meshing tooth and the second meshing tooth, thereby reducing the size of the stepper motor, improving the reliability of stepping, reducing costs, and meeting the requirements of reactor operating conditions.

[0022] Furthermore, the control rod drive system provided by the present invention also possesses the various advantages described above due to the presence of the stepper motor as described above. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the stepper motor provided by the present invention;

[0025] Figure 2 This is a top view of the stepping mechanism provided by the present invention;

[0026] Figure 3 yes Figure 2 A cross-sectional view along the AA direction;

[0027] Figure 4 Figure a is a schematic diagram of the drive wheel structure provided by the present invention, and Figure b is a cross-sectional view of a single first oblique hole or second oblique hole;

[0028] Figure 5 This is the first set of exploded views of the driving components provided by the present invention;

[0029] Figure 6 yes Figure 2 A cross-sectional view along the BB direction;

[0030] Figure 7 This is a schematic diagram of the self-locking positioning cylinder and drive wheel in a free state provided by the present invention;

[0031] Figure 8 This is an exploded view of the self-locking mechanism provided by the present invention.

[0032] Figure label:

[0033] 100: Stepping mechanism; 110: Drive piston assembly; 101: First set of drive components; 102: Second set of drive components; 111: Drive piston body; 112: Piston lead tube; 113: Piston outer sleeve; 114: Drive piston; 115: First spring; 116: Push rod; 117: Connector; 118: Seal; 120: Drive wheel; 121: First meshing tooth; 122: Second oblique hole; 123: First oblique hole;

[0034] 200: Self-locking mechanism; 201: Second meshing tooth; 202: Self-locking positioning cylinder; 203: Second spring; 204: Clutch disc; 205: Clutch lead tube; 206: Self-locking slider; 207: Mounting groove; 210: Piston assembly; 211: Sealing component; 212: Third spring; 213: Clutch piston; 214: Clutch body; 215: Fixing sleeve; 216: Channel; 217: Fixing component; 220: Outer cylinder;

[0035] 300: Fastening mechanism; 301: Pressure plate; 302: Base; 303: Locking bolt; 310: Output shaft. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] In the description of the embodiments of the present invention, it should be noted that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] The following is combined Figures 1 to 8 The embodiments of the present invention will be described below. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute a limitation thereof.

[0041] like Figures 1 to 3 As shown, the present invention provides a stepper motor, including: a stepping mechanism 100, a self-locking mechanism 200, and an output shaft 310. The stepping mechanism 100 includes a drive piston assembly 110 and a drive wheel 120. The drive piston assembly 110 reciprocates to drive the drive wheel 120 to step forward or backward. The drive wheel 120 includes a first meshing tooth 121. The self-locking mechanism 200 switches between a self-locked state and a free state. The self-locking mechanism 200 includes a second meshing tooth 201. In the self-locked state, the second meshing tooth 201 meshes with the first meshing tooth 121. In the free state, the second meshing tooth 201 disengages from the first meshing tooth 121. The output shaft 310 passes through the self-locking mechanism 200 and is connected to the drive wheel 120.

[0042] Specifically, each time the drive piston assembly 110 actuates, for example, each time it reciprocates axially, it drives the drive wheel 120 to rotate forward or backward by a certain angle. For example, each rotation of the drive wheel 120 causes the first meshing tooth 121 and the second meshing tooth 201 to misalign by one tooth. That is, the step angle of the drive wheel 120 is equal to the rotation angle of one tooth of the first meshing tooth 121. The rotation of the drive wheel 120 drives the output shaft 310 to rotate. The stepper motor of the present invention can meet the stepping rotation requirements in special environments, such as the quantitative driving of moving parts in the strong radiation environment of a nuclear reactor. It is smaller in size, more reliable, and lower in cost.

[0043] In the self-locking state, the first meshing tooth 121 and the second meshing tooth 201 are engaged with each other, preventing the output shaft 310 from rotating freely. Simultaneously, in the self-locking state, the rotating wheel can continuously step in one direction. During this stepping process, the first meshing tooth 121 and the second meshing tooth 201 remain in contact, with the contact position constantly changing, thereby enabling the first meshing tooth 121 to rotate relative to the second meshing tooth 201 in one direction. In other words, the self-locking mechanism 200 is axially extendable and radially limited. In the free state, the output shaft 310 can rotate freely, and the first meshing tooth 121 and the second meshing tooth 201 are spaced apart and completely disengaged.

[0044] Furthermore, in embodiments of the present invention, such as Figure 1 As shown, the stepper motor also includes a fastening mechanism 300, which includes a pressure plate 301, a base plate, and a locking bolt 303. The pressure plate 301 is installed above the stepper mechanism 100, and the base plate is installed below the self-locking mechanism 200. The locking bolt 303 passes through the pressure plate 301 and the base plate to connect and fix the stepper mechanism 100 and the self-locking mechanism 200 into a whole.

[0045] like Figure 2 As shown, in one embodiment of the present invention, the drive piston assembly 110 includes a first set of drive members 101 and a second set of drive members 102, the linear distances of the first set of drive members 101 and the second set of drive members 102 from the output shaft 310 are not equal. For example, the distance between the first set of drive members 101 and the output shaft 310 is less than the driving distance between the second set of drive members 102 and the output shaft 310. The first set of drive components is used to make the drive wheel 120 rotate forward, and the second set of drive components is used to make the drive wheel 120 rotate in reverse.

[0046] The drive piston assembly 110 includes multiple first-group drive members 101 and multiple second-group drive members 102. The centers of the multiple first-group drive members 101 are on the same circle. In other words, the multiple first-group drive members 101 are arranged axially on the output shaft 310 with the same radius distance, and are spaced apart. The multiple first-group drive members 101 work alternately to realize the step-by-step rotation of the drive wheel 120 in one direction. The multiple second-group drive members 102 are the same as the first-group drive members 101, and will not be described in detail here.

[0047] like Figure 3 and Figure 4 As shown, in another embodiment of the present invention, the drive wheel 120 includes a first oblique hole 123 and a second oblique hole 122. The first oblique holes 123 are equally spaced to form a first circle centered on the output shaft 310, and the second oblique holes 122 are equally spaced to form a second circle centered on the output shaft 310. The diameters of the first and second circles are not equal. A first set of drive members 101 engages with the first oblique hole 123, and a second set of drive members 102 engages with the second oblique hole 122. The inclination directions of the first oblique hole 123 and the second oblique hole 122 are opposite. The opening angles of the first oblique hole 123 and the second oblique hole 122 are the same, and they are circumferentially complementary, forming a 360° gapless connection in both directions.

[0048] Specifically, such as Figure 4 In Figure a, the first oblique hole 123 is arranged at equal intervals around the output shaft 310 to form a first circle. The first set of driving members 101 cooperates with the first oblique hole 123 to realize the step rotation of the drive wheel 120 in one direction, such as clockwise rotation. The length of one oblique hole is one step angle of the output shaft 310. Similarly, the second oblique hole 122 is arranged at equal intervals around the output shaft 310 to form a second circle. The second set of driving members 102 cooperates with the second oblique hole 122 to realize the step rotation of the drive wheel 120 in another direction, such as counterclockwise rotation. The distance of one oblique hole is one step angle of the output shaft 310. The first circle formed by the first oblique hole 123 and the second circle formed by the second oblique hole 122 are concentric circles. For example, the diameter of the first circle is smaller than the diameter of the second circle. In addition, each first oblique hole 123 and each second oblique hole 122 makes the step angle of the output shaft 310 equal.

[0049] like Figure 4Figure b illustrates the structure of the first oblique hole 123 and the second oblique hole 122 of the present invention. The structures of the first oblique hole 123 and the second oblique hole 122 are identical. For a single oblique hole, it comprises an inclined surface and a straight surface, which are continuous. The inclined surface is positioned above the straight surface, and the inclined surface and straight surface form a funnel shape within the oblique hole. For example, when the first set of driving members 101 extends, it contacts the inclined surface and moves along the inclined surface into the hole formed by the straight surface. After completing one step, the first set of driving members 101 retracts. During the next step, the first set of driving members 101 extends into the inclined surface of the next first oblique hole 123, completing the next step. The inclined surfaces of the first oblique hole 123 and the second oblique hole 122 have opposite directions, thereby realizing the forward and reverse rotation of the output shaft 310.

[0050] Continue to refer to Figure 2 and Figure 3 In one specific embodiment of the present invention, the first set of driving members 101 includes at least two, each of which engages with the first oblique hole 123 and operates alternately. For example, the drive piston assembly 110 includes two first set of driving members 101 and two second set of driving members 102. The two first set of driving members 101 are arranged on the same circle at a certain angle, and the two second set of driving members 102 are arranged on the same circle at a certain angle. During the forward rotation of the output shaft 310, the two first set of driving members 101 alternately extend and retract to engage with the first oblique hole 123 to achieve forward stepping; during the reverse rotation of the output shaft 310, the two second set of driving members 102 alternately extend and retract to engage with the second oblique hole 122 to achieve reverse stepping.

[0051] like Figure 3 and Figure 5 As shown, in some embodiments of the present invention, the first set of driving members 101 and the second set of driving members 102 have the same structure, including a piston lead tube 112, a driving piston 114, a first spring 115 and a push rod 116. The piston lead tube 112 drives the driving piston 114 to move toward the driving wheel 120 through a driving medium. The first spring 115 is used to reset the driving piston 114. The push rod 116 is connected to the driving piston 114 and is used to push the driving wheel 120 to rotate.

[0052] Specifically, the piston lead tube 112 is positioned above the drive piston 114, the first spring 115 is positioned between the drive piston 114 and the drive wheel 120, and the push rod 116 is connected to the drive piston 114. The piston lead tube 112 fills the drive piston 114 with driving medium, which pushes the drive piston 114 to move downward along the axial direction. During the movement, the first spring 115 is compressed, and the push rod 116 is driven to engage with the first inclined hole 123 or the second inclined hole 122 of the drive wheel 120. After the push rod 116 has completed its movement within the first inclined hole 123 or the second inclined hole 122, the drive wheel 120 steps forward a certain angle in one direction, the piston lead tube 112 releases pressure, and the drive piston 114 returns to its original position under the restoring force of the first spring 115. The push rod 116 is then lifted, completing one extension or reciprocating motion along the axial direction.

[0053] Furthermore, such as Figure 5 Specifically, the first set of driving components 101 and the second set of driving components 102 also include a piston sleeve 113, a connector 117, and a seal 118. A piston lead tube 112 passes through the piston sleeve 113 and communicates with the inner cavity of the piston sleeve 113. The piston lead tube 112 is connected to the piston sleeve 113 via the connector 117. A driving piston 114 is disposed in the inner cavity of the piston sleeve 113, and the driving piston 114 and the inner sidewall of the piston sleeve 113 are provided with seals 118.

[0054] In addition, the stepping mechanism 100 also includes a drive piston 114 and a drive piston body 111. The upper part of the drive piston body 114 has a groove for placing the drive piston assembly 110. A piston sleeve 113 is placed in the groove and can be threadedly connected to the drive piston body 114. The bottom of the drive piston 114 has an annular groove. A first spring 115 is sleeved on the annular groove. The upper part of the first spring 115 abuts against the drive piston 114, and the lower part of the first spring 115 abuts against the bottom of the groove in the drive piston body 111. A push rod 116 can be threadedly connected to the drive piston 114. One end of the push rod 116 passes through the drive piston body 114 and engages with the first oblique hole 123 or the second oblique hole 122 of the drive wheel 120.

[0055] The output shaft 310 passes through the drive wheel 120 and is rotatably connected to the drive piston 114 body 111.

[0056] Furthermore, in other embodiments of the present invention, the driving medium within the piston lead tube 112 is a gas or a liquid. For example, the gas can be compressed air, inert gas, etc., and the liquid can be water or hydraulic oil, etc. The pneumatic or hydraulic piston lead tube 112 makes the stepper motor smaller, more reliable, and less expensive.

[0057] like Figures 6 to 8 As shown, in one embodiment of the present invention, the self-locking mechanism 200 further includes a self-locking cylinder 202, a second spring 203 and a clutch assembly. The second engagement tooth 201 is disposed on the self-locking cylinder 202, and the second spring 203 is disposed between the self-locking cylinder 202 and the clutch assembly. The clutch assembly is used to switch between the self-locking state and the free state.

[0058] Specifically, in the self-locking state, the clutch assembly drives the second spring 203 and the self-locking sleeve 202 to move linearly towards the drive wheel 120, and engages the second meshing tooth 201 with the first meshing tooth 121. During the stepping process of the stepping mechanism 100, the first meshing tooth 121 rotates relative to the second meshing tooth 201 in one direction. As the first meshing tooth 121 advances one tooth, the second meshing tooth 201 is first pushed downward along the axial direction, and the second spring 203 is compressed. Then, when the first meshing tooth 121 engages with the next tooth of the second meshing tooth 201, the second spring 203 drives the self-locking sleeve 202 to reset, so that the first meshing tooth 121 and the second meshing tooth 201 are tightly engaged. In other words, the second spring 203 keeps the first meshing tooth 121 and the second meshing tooth 201 in a self-locking state during relative rotation, realizing the reciprocating motion of the self-locking sleeve 202 along the axial direction.

[0059] In the free state, the clutch assembly drives the self-locking cylinder 202 to move downward along the axial direction, thereby disengaging the first engagement tooth 121 and the second engagement tooth 201. The output shaft 310 is rotatably connected to the clutch assembly, and in the free state, the output shaft 310 can rotate freely.

[0060] like Figure 7 and Figure 8 As shown, in a specific embodiment of the present invention, the self-locking mechanism 200 further includes an outer cylinder 220. The self-locking positioning cylinder 202, the second spring 203, and the clutch assembly are all placed inside the outer cylinder 220. The outer cylinder 220 is connected to the driving piston 114 body 111 of the stepping mechanism 100 via a positioning pin. A mounting groove 207 along the axial direction is formed on the outer wall of the self-locking positioning cylinder 202, and a self-locking slider 206 is placed in the mounting groove 207. A guide groove along the axial direction is formed on the inner wall of the outer cylinder 220, and the self-locking slider 206 slides in the guide groove, thereby realizing linear movement of the self-locking positioning cylinder 202 along the axial direction of the outer cylinder 220, and radial rotation limitation.

[0061] Furthermore, such as Figure 6 and Figure 7As shown, in some other embodiments of the present invention, the clutch assembly includes a clutch disc 204, a piston assembly 210, and a clutch lead tube 205. The clutch disc 204 and the self-locking cylinder 202 are connected to the piston assembly 210. A second spring 203 is provided between the clutch disc 204 and the self-locking cylinder 202. The clutch lead tube 205 is used to push the piston assembly 210. In the self-locking state, the clutch lead tube 205 fills the piston assembly 210 with a clutch medium, causing the piston assembly 210 to push the clutch disc 204 and the self-locking cylinder 202 upward, so that the self-locking cylinder 202 contacts the drive wheel 120. In the free state, the piston assembly 210 drives the clutch disc 204 and the self-locking cylinder 202 downward, so that the self-locking cylinder 202 disengages from the drive wheel 120.

[0062] Specifically, the clutch lead tube 205 fills the clutch assembly with a clutch medium, thereby pushing the piston assembly 210, causing the piston assembly 210 to move linearly along the axial direction. After the clutch lead tube 205 releases pressure, the piston assembly 210 resets. When the piston assembly 210 moves linearly towards the stepping mechanism 100, it drives the clutch disc 204 and the self-locking cylinder 202 upwards until the second engagement tooth 201 of the self-locking cylinder 202 engages with the first engagement tooth 121, entering a self-locking state. When switching from the self-locking state to the free state, the clutch lead tube 205 releases pressure, the piston assembly 210 resets, and the clutch disc 204 and the self-locking cylinder 202 fall back, leaving a gap between the self-locking cylinder 202 and the drive wheel 120.

[0063] The clutch medium in the clutch lead tube 205 can be a gas or a liquid. For example, the gas can be compressed air, inert gas, etc., and the liquid can be water or hydraulic oil, etc.

[0064] Furthermore, in another specific embodiment of the present invention, the piston assembly 210 includes a clutch piston 213, a third spring 212, and a sealing member 211. The third spring 212 is placed between the sealing member 211 and the clutch piston 213. In the self-locking state, the clutch piston 213 compresses the third spring 212, causing the sealing member 211 to press against the clutch disc 204. In the free state, the third spring 212 resets the clutch piston 213, creating a gap between the clutch piston 213 and the sealing member 211.

[0065] Specifically, the clutch lead tube 205 is filled with clutch medium, which pushes the clutch piston 213 to move linearly along the axial direction. In the self-locking state, the clutch piston 213, pushed by the clutch medium, compresses the third spring 212, causing the clutch piston 213 to push the sealing component 211 to move. The self-locking positioning cylinder 202 contacts the drive wheel 120, achieving self-locking. After the step is completed, the clutch lead tube 205 releases pressure, and the clutch piston 213 falls back to its original position under the restoring force of the third spring 212. A gap is formed between the clutch piston 213 and the sealing component 211, the piston assembly 210 falls back as a whole, a gap is formed between the self-locking positioning cylinder 202 and the drive wheel 120, and the output shaft 310 enters the free state.

[0066] In addition, such as Figure 6 and Figure 8 As shown, in an embodiment of the present invention, the clutch assembly further includes a clutch body 214 and a fixing sleeve 215. The clutch body 214 is disposed between the clutch disc 204 and the piston assembly 210. The upper end of the clutch body 214 is connected to the sealing member 211 and can be secured by an anti-loosening screw, which limits the clutch stroke of the clutch piston 213. A step is provided at the lower end of the clutch body 214, and the outer cylinder 220, the self-locking positioning cylinder 202, and the clutch disc 204 are all placed on the step. In the self-locking state, there is a gap between the self-locking positioning cylinder 202 and the clutch disc 204 and the step of the clutch body 214, and there is a gap between the clutch disc 204 and the sealing member 211. In the free state, the self-locking positioning cylinder 202 and the clutch disc 204 are in contact with the step of the clutch body 214, and the clutch disc 204 is in contact with the sealing member 211.

[0067] Furthermore, a channel 216 is provided on the clutch body 214, which connects the clutch lead tube 205 to the chamber where the clutch piston 213 is located, so that the clutch medium acts on the step of the clutch piston 213, pushing the clutch piston 213 upward. In this invention, upward movement refers to movement along the axial direction of the output shaft 310 towards the pressure plate 301, and downward movement refers to movement along the axial direction of the output shaft 310 towards the base 302.

[0068] The fixed sleeve 215 is fitted onto the output shaft 310. The self-locking positioning cylinder 202 and the clutch assembly are both located on the outer wall of the fixed sleeve 215. The clutch piston 213 is threadedly connected to the fixed sleeve 215, and can be secured by an anti-loosening screw. The clutch disc 204 is connected to the fixed sleeve 215, and the self-locking positioning cylinder 202 is connected to the fixed sleeve 215 via a fixing member 217. In the self-locking state, the clutch lead tube 205 is filled with clutch medium, causing the clutch piston 213 to move upward, which in turn moves the fixed sleeve 215 upward. The fixed sleeve 215 then moves the clutch disc 204 and the self-locking positioning cylinder 202 upward. When the clutch piston 213 compresses the third spring 212 and contacts the sealing member 211, the fixed sleeve 215 moves to its upper limit. At this time, the second meshing tooth 201 of the self-locking positioning cylinder 202 meshes with the first meshing tooth 121 of the drive wheel 120. The piston lead tube 112 of the drive piston assembly 110 injects driving medium into the drive piston 114, causing the drive piston 114 to drive the push rod 116 downward. The push rod 116 engages with the first oblique hole 123 or the second oblique hole 122 on the drive wheel 120, and steps in one direction. After the stepping is completed, the clutch lead tube 205 releases pressure, and under the action of the third spring 212, the clutch piston 213 returns to its original position and falls, thereby causing the fixed sleeve 215 to fall, causing the self-locking sleeve 202 to disengage from the drive wheel 120, forming a gap, and the clutch disc 204 falls onto the step of the clutch body 214.

[0069] The present invention also provides a control rod driving system, including the stepper motor of the above embodiment.

[0070] The stepper motor provided by this invention drives the drive wheel 120 to rotate in both directions via the reciprocating motion of the drive piston assembly 110, thereby achieving the rotational stepping of the output shaft 310. The engagement and disengagement of the first meshing tooth 121 and the second meshing tooth 201 switch between the self-locking and free states of the output shaft 310, thus reducing the size of the stepper motor, improving stepping reliability, lowering costs, and meeting the requirements of reactor operation. It satisfies engineering applications in space reactors, research reactors, high-flux reactors, and other reactors, and also provides a reference for the engineering design of rotation drive control in other industrial fields. It solves the problem of gas or liquid-driven stepping rotation, as well as the problem of quantitative drive technology for moving parts in special environments, such as the strong radiation environment of nuclear reactors.

[0071] Furthermore, the control rod drive system provided by the present invention also possesses the various advantages described above due to the presence of the stepper motor as described above.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stepper motor, characterized in that, include: A stepping mechanism, comprising a drive piston assembly and a drive wheel, wherein the drive piston assembly reciprocates to drive the drive wheel to step forward or backward, and the drive wheel includes a first meshing tooth; The self-locking mechanism switches between a self-locking state and a free state. The self-locking mechanism includes a second meshing tooth. In the self-locking state, the second meshing tooth meshes with the first meshing tooth. In the free state, the second meshing tooth disengages from the first meshing tooth. An output shaft passes through the self-locking mechanism and is connected to the drive wheel.

2. The stepper motor according to claim 1, characterized in that, The drive piston assembly includes a first set of drive components and a second set of drive components, wherein the first set of drive components and the second set of drive components are not equidistant from the output shaft.

3. The stepper motor according to claim 2, characterized in that, The drive wheel includes a first oblique hole and a second oblique hole. The first oblique hole forms a first circle with the output shaft as the center at equal intervals. The second oblique hole forms a second circle with the output shaft as the center at equal intervals. The diameters of the first circle and the second circle are not equal. The first set of driving components mates with the first oblique hole, and the second set of driving components mates with the second oblique hole. The first oblique hole and the second oblique hole have opposite inclination directions.

4. The stepper motor according to claim 3, characterized in that, The first set of driving components includes at least two, each of which engages with the first oblique hole and operates alternately.

5. The stepper motor according to claim 2, characterized in that, The first set of driving components and the second set of driving components have the same structure, including a piston guide tube, a driving piston, a first spring and a push rod. The piston guide tube drives the driving piston to move towards the driving wheel through a driving medium. The first spring is used to reset the driving piston. The push rod is connected to the driving piston and is used to push the driving wheel to rotate.

6. The stepper motor according to claim 5, characterized in that, The driving medium inside the piston lead tube is gas or liquid.

7. The stepper motor according to any one of claims 1 to 6, characterized in that, The self-locking mechanism further includes a self-locking cylinder, a second spring, and a clutch assembly. The second engagement tooth is disposed on the self-locking cylinder, and the second spring is placed between the self-locking cylinder and the clutch assembly. The clutch assembly is used to switch between the self-locking state and the free state.

8. The stepper motor according to claim 7, characterized in that, The clutch assembly includes a clutch disc, a piston assembly, and a clutch lead tube. The clutch disc and the self-locking cylinder are connected to the piston assembly. A second spring is provided between the clutch disc and the self-locking cylinder. The clutch lead tube is used to push the piston assembly. In the self-locking state, the clutch lead tube introduces clutch medium into the piston assembly, causing the piston assembly to push the clutch disc and self-locking cylinder upward; in the free state, the piston assembly drives the clutch disc and self-locking cylinder downward.

9. The stepper motor according to claim 8, characterized in that, The piston assembly includes a clutch piston, a third spring, and a sealing element, wherein the third spring is positioned between the sealing element and the clutch piston. In the self-locking state, the clutch piston compresses the third spring, causing the sealing member to press against the clutch disc; in the free state, the third spring resets the clutch piston, creating a gap between the clutch piston and the sealing member.

10. A control rod driving system, characterized in that, The stepper motor includes any one of claims 1 to 9.

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