Magnetic coupling and control rod driving mechanism equipped with same

Abstract

This magnetic coupling magnetically couples an output shaft (91) and an input shaft (92) via a partition wall (62) positioned between the output shaft (91) and the input shaft (92), the magnetic coupling comprising magnet groups (95, 96) provided on one shaft-facing surface of facing surfaces (91c, 92a) of the output shaft (91) and the input shaft (92), first magnets (95a, 95b, 96a, 96b) magnetized in the circumferential direction of one shaft, and second magnets (95c, 95d, 96c, 96d) magnetized in the radial direction of one shaft being alternately arranged along the circumferential direction of the one shaft in the magnet groups (95, 96), and the thickness of the first magnets (95a, 95b, 96a, 96b) and the thickness of the second magnets (95c, 95d, 96c, 96d) in the radial direction of the one axis being different.

Description

Magnetic coupling and control rod drive mechanism equipped with the same

[0006] ,

[0005] ,

[0001] The present invention relates to a magnetic coupling and a control rod drive mechanism equipped with the same.

[0002] In order to control the nuclear fission chain reaction of a nuclear reactor, it is necessary to adjust the number of neutrons in the nuclear reactor to control the reactivity. In a stopped nuclear reactor, control rods made of a control material that absorbs neutrons are inserted to absorb the neutrons generated in the nuclear fission reaction so as not to reach a critical state. When starting up the nuclear reactor, the number of neutrons in the nuclear reactor is increased by pulling out the control rods, and the reactivity is increased. In an emergency, the nuclear reactor is stopped by inserting all the control rods.

[0003] As a mechanism for driving the control rods, there is an improved control rod drive mechanism in which the emergency insertion operation is hydraulically driven and the reactivity control during startup and operation is electrically driven. Compared with the conventional drive mechanism using only hydraulic drive, this drive mechanism has improved operability due to miniaturized driving and enhanced nuclear reactor stop function during emergencies due to diversification of drive sources. The electric motor is installed outside the pressure vessel in which the nuclear fuel is stored, while the control rod is installed inside the pressure vessel. Therefore, a non-contact coupling capable of transmitting the torque of the electric motor to the control rod through the pressure vessel is required. That is, as the coupling of the improved control rod drive mechanism, it is preferable to adopt the latter of a direct connection type and a non-contact type (for example, a magnetic coupling using magnetic force).

[0004] In relation to this type of technology, in Patent Document 1, regarding the magnetic coupling of a driving device and a driven device through a partition wall, a plurality of magnets are arranged in a Halbach array on each of the output shaft and the input shaft so as to increase the transmission torque from the output shaft of the driving device to the input shaft of the driven device (that is, magnets with different magnetization directions are arranged in the circumferential direction) is disclosed.

[0005] Japanese Patent Application Laid-Open No. 2019-199891

[0006] In the magnetic coupling described in Patent Document 1, the magnetic coupling portion between the output shaft and the input shaft has groups of magnets arranged in a Halbach array on each of the opposing surfaces (opposing surfaces) of the output shaft and the input shaft. The outer shape of each magnet group in Patent Document 1 is cylindrical, and the outer or inner surface of the cylinder is coupled to the output shaft or input shaft. Therefore, if the coupling between the cylindrical magnet group and the shaft (output shaft or input shaft) weakens, for example, over time, the magnet group may rotate freely relative to the output shaft or input shaft, potentially hindering torque transmission from the output shaft to the input shaft.

[0007] The object of the present invention is to provide a magnetic coupling that can prevent a group of magnets arranged in a Halbach array from free-rotating relative to the output shaft or input shaft, and which is provided in the magnetic coupling portion of the magnetic coupling.

[0008] The present invention includes several means for solving the above problems, but to give one example, a magnetic coupling that magnetically connects an output shaft and an input shaft via a partition wall located between the output shaft and the input shaft, comprising a group of magnets provided on the opposing surface of one of the opposing surfaces of the output shaft and the input shaft, wherein the group of magnets consists of a first magnet magnetized in the circumferential direction of the one shaft and a second magnet magnetized in the radial direction of the one shaft, which are alternately arranged along the circumferential direction of the one shaft, and the thickness of the first magnet and the thickness of the second magnet in the radial direction of the one shaft are different.

[0009] According to the present invention, irregularities are formed in the magnet group by two types of magnets with different thicknesses in the radial direction of one shaft (output shaft or input shaft), and by engaging these irregularities with the one shaft, the occurrence of free rotation of the magnet group relative to the one shaft can be suppressed. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

[0010] This is a partial cross-sectional view of a control rod drive mechanism according to an embodiment of the present invention. This is a cross-sectional view taken along line II-II in Figure 1. This is a cross-sectional view of the cylindrical portion of the outer yoke. This is a cross-sectional view of the inner yoke. This is a schematic diagram showing the flow of magnetic flux in a part of the cross-section of the outer rotor into which a circumferentially magnetized magnet is fitted in a recess of the outer yoke. This is a schematic diagram showing the flow of magnetic flux in a part of the cross-section of the outer rotor into which a radially magnetized magnet is fitted in a recess of the outer yoke.

[0011] The configuration and operation of a magnetic coupling and a control rod drive mechanism equipped therewith, according to an embodiment of the present invention, will be described below with reference to the drawings. In each figure, the same reference numerals indicate the same part.

[0012] Figure 1 is a partial cross-sectional view of a control rod drive mechanism 1 according to an embodiment of the present invention.

[0013] The control rod drive mechanism 1 is a device for moving the control rod 3, which is protected by the control rod guide tube 2, in and out of the space between the fuel rods of the fuel assembly inside the reactor pressure vessel 4, which is filled with reactor water 4a.

[0014] The control rod drive mechanism 1 comprises a drive mechanism body 5 housed within the housing 4b of the control rod drive mechanism 1, and a lower component 6 attached to the lower part of the drive mechanism body 5. The drive mechanism body 5 and the lower component 6 are flange-fastened to the lower part of the housing 4b by bolts 4c.

[0015] The drive mechanism body 5 is a component that moves the control rod 3 up and down, and includes a hollow piston 51 connected to the control rod 3, a ball nut 52 that supports the hollow piston 51, a ball screw 53 that engages with the ball nut 52, and an outer tube 54 that covers them.

[0016] The drive mechanism body 5 rotates the ball screw 53 to cause the ball nut 52 to move vertically up and down, and moves the control rod 3 connected to the hollow piston 51 supported by the ball nut 52 up and down.

[0017] The lower component 6 is a component that rotates the electric motor 7, which is the drive source, and transmits rotational force to the ball screw 53 of the drive mechanism body 5. It comprises the electric motor 7, a retaining brake 8, and a magnetic coupling 9.

[0018] The electric motor 7 is a power source for moving the control rod 3 up and down, and is located at the lower end of the lower component 6.

[0019] The holding brake 8 is a device that grips the rotating shaft of the electric motor 7 when the electric motor 7 is stopped, preventing the control rod 3 from descending due to the rotation of the ball screw 53 caused by the weight of the control rod 3. It is positioned and mounted above the electric motor 7.

[0020] A magnetic coupling 9 is provided between the holding brake 8 and the drive mechanism body 5.

[0021] The magnetic coupling 9 is a device that magnetically connects the output shaft 91 and the input shaft 92 via a partition wall 62 located between the output shaft 91 and the input shaft 92.

[0022] The magnetic coupling 9 preferably has a double cylindrical structure at the magnetic coupling portion between the output shaft 91 and the input shaft 92, and comprises an outer rotor 91 that forms the output shaft and an inner rotor 92 that forms the input shaft.

[0023] The outer rotor 91 is a cylindrical component attached to the outer tube 54 and covers the lower cylindrical portion 62 of the spool piece 61, which forms part of the reactor pressure vessel 4.

[0024] The bottom plate portion 91a of the outer rotor 91 is attached to a shaft 93 that is connected to the output shaft of the electric motor 7 via a retaining brake 8, and it is preferable that the outer rotor 91 forms the output shaft of the magnetic coupling 9.

[0025] The inner rotor 92 is a cylindrical component located within the cylindrical body portion 62, and is attached to a shaft 94 that connects to the ball screw 53 and rotates the ball screw 53, preferably forming the input shaft of the magnetic coupling 9.

[0026] Preferably, the ball screw 53 is assembled with the ball nut 52, and by rotating the ball screw 53, the ball nut 52 is moved in a linear motion, thereby moving the control rod 3, which is connected to the hollow piston 51 supported by the ball nut 52, up and down. Therefore, it is preferable that the input shaft 92 is the driven shaft of the control rod 3.

[0027] Furthermore, the inner circumferential surface 91c of the cylindrical portion 91b of the outer rotor 91 and the outer circumferential surface 92a of the inner rotor 92 face each other via the lower cylindrical portion 62 of the spool piece 61. That is, the outer rotor 91 is formed to surround the lower cylindrical portion 62 of the spool piece 61, and the inner rotor 92 is positioned within the lower cylindrical portion 62 of the spool piece 61.

[0028] Therefore, the lower cylindrical portion 62 of the spool piece 61 is positioned as a partition between the outer rotor 91 and the inner rotor 92. Thus, the magnetic coupling 9 magnetically connects the output shaft (outer rotor 91) and the input shaft (inner rotor 92) via the partition (cylindrical portion 62 of the spool piece 61) located between the output shaft (outer rotor 91) and the input shaft (inner rotor 92).

[0029] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. In Figure 2, the arrows shown on the cross-sections of magnets 95a-95d and 96a-96d indicate the direction of magnetization of magnets 95a-95d and 96a-96d.

[0030] As shown in Figure 2, a magnet group 95 is provided on the outer circumferential surface 92a of the input shaft (inner rotor 92) and on the inner circumferential surface 91c of the cylindrical portion 91b of the output shaft (outer rotor 91), which is opposed via a cylindrical portion 62. In addition, a magnet group 96 is provided on the outer circumferential surface 92a of the input shaft (inner rotor 92), which is opposed via a cylindrical portion 62 that is opposed to the inner circumferential surface 91c of the cylindrical portion 91b of the output shaft (outer rotor 91).

[0031] Specifically, the outer rotor 91 has a cylindrical outer yoke 97 and a group of magnets 95 that engage with the inner circumferential surface of the outer yoke 97. The inner rotor 92 has a cylindrical inner yoke 98 and a group of magnets 96 that engage with the outer circumferential surface of the inner yoke 98.

[0032] In the magnet group 95 provided on the inner circumferential surface 91c of the cylindrical portion 91b of the output shaft (outer rotor 91), first magnets (circumferentially magnetized magnets 95a, 95b) magnetized in the circumferential direction of the output shaft of the magnetic coupling 9 and second magnets (radially magnetized magnets 95c, 95d) magnetized in the radial direction of the output shaft of the magnetic coupling 9 are alternately arranged along the circumferential direction of the output shaft of the magnetic coupling 9.

[0033] Furthermore, in the magnet group 96 provided on the outer circumferential surface 92a of the input shaft (inner rotor 92), first magnets (circumferentially magnetized magnets 96a, 96b) magnetized in the circumferential direction of the input shaft of the magnetic coupling 9 and second magnets (radially magnetized magnets 96c, 96d) magnetized in the radial direction of the output shaft of the magnetic coupling 9 are alternately arranged along the circumferential direction of the input shaft of the magnetic coupling 9.

[0034] Furthermore, in the radial direction of the output shaft of the magnetic coupling 9, the thickness of the first magnets (circumferentially magnetized magnets 95a, 95b) and the thickness of the second magnets (radially magnetized magnets 95c, 95d) of the magnet group 95 on the inner circumferential surface of the cylindrical portion 91b of the output shaft (outer rotor 91) are different.

[0035] Furthermore, in the radial direction of the input shaft of the magnetic coupling 9, the thickness of the first magnets (circumferentially magnetized magnets 96a, 96b) and the thickness of the second magnets (radially magnetized magnets 96c, 96d) of the magnet group 96 on the outer surface of the input shaft (inner rotor 92) are different.

[0036] The magnet group 95 of the output shaft of the magnetic coupling 9, which has different thicknesses in the radial direction, engages with the outer yoke 97 of the output shaft (outer rotor 91) by means of an adhesive, for example. Similarly, the magnet group 96 of the input shaft of the magnetic coupling 9, which has different thicknesses in the radial direction, engages with the inner yoke 98 of the input shaft (inner rotor 92) by means of an adhesive, for example.

[0037] As shown in Figure 1, the outer yoke 97 is a cylindrical magnetic material (for example, magnetic stainless steel) that surrounds the lower cylindrical portion 62 of the spool piece 61, and comprises a bottom plate portion 91a of the outer rotor 91 and an outer peripheral portion 97a that forms the outer circumference of the cylindrical portion 91b of the outer rotor 91.

[0038] Figure 3 is a cross-sectional view of the outer peripheral portion 97a of the outer yoke 97. As shown in Figure 3, it is preferable that the coupling portion 91d (see Figure 2) between the output shaft (outer rotor 91) of the magnetic coupling 9 and the magnet group 95 is provided with a plurality of recesses 97b into which the thicker magnets among the magnet group 95, which have different thicknesses in the radial direction of the output shaft of the magnetic coupling 9, are fitted. Furthermore, it is preferable that the surface 91c of the magnet group 95 located on the opposite side of the coupling portion 91d between the outer rotor 91 and the magnet group 95 in the radial direction of the output shaft of the magnetic coupling 9, forms the inner surface of a cylinder, as shown in Figure 2.

[0039] Figure 4 is a cross-sectional view of the inner yoke 98. As shown in Figure 4, it is preferable that the coupling portion 92b (see Figure 2) between the input shaft (inner rotor 92) of the magnetic coupling 9 and the magnet group 96 is provided with a plurality of recesses 98a into which the thicker magnets among the magnet group 96, which have different thicknesses in the radial direction of the input shaft of the magnetic coupling 9, are fitted. Furthermore, it is preferable that the surface 92a of the magnet group 96 located on the opposite side of the coupling portion 92b between the inner rotor 92 and the magnet group 96 in the radial direction of the input shaft of the magnetic coupling 9 forms a cylindrical outer surface, as shown in Figure 2.

[0040] Furthermore, in the radial direction of the output shaft of the magnetic coupling 9, it is preferable that the thickness of the first magnet (circumferentially magnetized magnets 95a, 95b) of the magnet group 95 on the inner circumferential surface 91c of the cylindrical portion 91b of the outer rotor 91 is greater than the thickness of the second magnet (radially magnetized magnets 95c, 95d).

[0041] Furthermore, in the radial direction of the input shaft of the magnetic coupling 9, it is preferable that the thickness of the first magnet (circumferentially magnetized magnets 96a, 96b) of the magnet group 96 on the outer circumferential surface 92a of the inner rotor 92 is greater than the thickness of the second magnet (radially magnetized magnets 96c, 96d).

[0042] Further, each of the first magnets (circumferentially magnetized magnets 95a and 95b) and the second magnets (radially magnetized magnets 95c and 95d) of the magnet group 95 on the inner peripheral surface of the cylindrical portion 91b of the outer rotor 91 preferably extends along the output shaft and has an annular fan-shaped cross-sectional shape with respect to the output shaft.

[0043] Further, each of the first magnets (circumferentially magnetized magnets 96a and 96b) and the second magnets (radially magnetized magnets 96c and 96d) of the magnet group 96 on the outer peripheral surface of the inner rotor 92 preferably extends along the input shaft and has an annular fan-shaped cross-sectional shape with respect to the output shaft.

[0044] Further, each of the plurality of recesses 97b provided on the inner peripheral surface of the outer yoke 97 preferably extends along the output shaft of the magnetic coupling 9, and has a fan-shaped groove cross-sectional shape with respect to the output shaft of the magnetic coupling 9.

[0045] Further, each of the plurality of recesses 98a provided on the outer peripheral surface 92a of the inner yoke 98 preferably extends along the input shaft of the magnetic coupling 9, and has a fan-shaped groove cross-sectional shape with respect to the input shaft of the magnetic coupling 9.

[0046] The radially magnetized magnets (second magnets) of the magnet group 95 on the inner peripheral surface of the cylindrical portion 91b of the outer rotor 91 preferably include a third magnet (radially magnetized magnet 95c) magnetized in the direction toward the opposing surface 92a between the output shaft 91 and the input shaft 92, and a (radially magnetized magnet 95d) magnetized in the direction away from the opposing surface 92a between the output shaft 91 and the input shaft 92.

[0047] Specifically, the third magnet of the magnet group 95 is a radially magnetized magnet 95c magnetized in the radially inner diameter side direction of the outer rotor 91, which is the direction toward the outer peripheral surface 92a of the inner rotor 92 facing the inner peripheral surface 91c of the cylindrical portion 91b of the outer rotor 91.

[0048] Further, the fourth magnet of the magnet group 95 is a radially magnetized magnet 95d magnetized in the radially outer diameter side direction of the outer rotor 91, which is the direction away from the outer peripheral surface 92a of the inner rotor 92 facing the inner peripheral surface 91c of the cylindrical portion 91b of the outer rotor 91.

[0049] Preferably, the circumferentially magnetized magnet (first magnet) of the magnet group 95 on the inner circumferential surface of the cylindrical portion 91b of the outer rotor 91 is formed by a fifth magnet magnetized toward the third magnet 95c in the circumferential direction of the outer rotor 91, and a sixth magnet magnetized toward the fourth magnet 95d in the circumferential direction of the outer rotor 91.

[0050] In detail, the circumferentially magnetized magnets (first magnets) of the magnet group 95 on the inner circumferential surface of the cylindrical portion 91b of the outer rotor 91 are formed by a circumferentially magnetized magnet 95a that is magnetized in one direction of the outer rotor 91, for example clockwise, and a circumferentially magnetized magnet 95b that is magnetized in the other direction of the outer rotor 91, for example counterclockwise.

[0051] The fifth magnet is a magnet in which a circumferentially magnetized magnet 95a magnetized clockwise and a circumferentially magnetized magnet 95b magnetized counterclockwise are arranged such that their magnetization directions are directed toward the third magnet 95c in the circumferential direction of the outer rotor 91.

[0052] Furthermore, the sixth magnet is a magnet in which a circumferentially magnetized magnet 95a magnetized clockwise and a circumferentially magnetized magnet 95b magnetized counterclockwise are arranged such that their magnetization directions are oriented away from the fourth magnet 95d in the circumferential direction of the outer rotor 91.

[0053] It is preferable that the circumferentially magnetized magnets 95a, 95b and the radially magnetized magnets 95c, 95d are arranged alternately in the circumferential direction in a predetermined arrangement on the inner surface of the outer yoke 97.

[0054] The predetermined arrangement is a Halbach arrangement that concentrates the magnetic force radially inward of the outer yoke 97, and it is preferable that the third magnet, fifth magnet, fourth magnet 95d, and sixth magnet are repeatedly arranged in this order in the circumferential direction of the axis of the outer yoke 97.

[0055] More specifically, as shown in Figure 2, a radially magnetized magnet 95c, which is magnetized in the inner diameter direction, is flanked by a circumferentially magnetized magnet 95a, which is magnetized clockwise, and a circumferentially magnetized magnet 95b, which is magnetized counterclockwise, both arranged with their magnetization directions directed toward the radially magnetized magnet 95c.

[0056] Furthermore, on either side of the radially magnetized magnet 95d, which is magnetized in the outer diameter direction, a circumferentially magnetized magnet 95a, which is magnetized clockwise, and a circumferentially magnetized magnet 95b, which is magnetized counterclockwise, are arranged with their magnetization directions directed away from the radially magnetized magnet 95d.

[0057] This allows the outer rotor 91 to concentrate the magnetic force radially inward toward the outer yoke 97.

[0058] Furthermore, it is preferable that the radially magnetized magnet (second magnet) of the magnet group 96 on the outer circumferential surface 92a of the inner rotor 92 has a third magnet (radially magnetized magnet 96c) magnetized in the direction toward the opposing surface 92a between the output shaft 91 and the input shaft 92, and a fourth magnet (radially magnetized magnet 96d) magnetized in the direction away from the opposing surface 92a between the output shaft 91 and the input shaft 92.

[0059] In detail, the third magnet of the magnet group 96 is a radially magnetized magnet 96c that is magnetized on the radially outer diameter side of the inner rotor 92, in the direction toward the inner circumferential surface 91c of the cylindrical portion 91b of the outer rotor 91 that faces the outer circumferential surface 92a of the inner rotor 92.

[0060] Furthermore, the fourth magnet of the magnet group 96 is a radially magnetized magnet 96d that is magnetized on the radially inner diameter side of the inner rotor 92, in a direction away from the inner circumferential surface 91c of the cylindrical portion 91b of the outer rotor 91 that faces the outer circumferential surface 92a of the inner rotor 92.

[0061] Preferably, the circumferentially magnetized magnet (first magnet) of the magnet group 96 on the inner circumferential surface of the inner rotor 92 is formed by a fifth magnet magnetized toward the third magnet 96c in the circumferential direction of the inner rotor 92, and a sixth magnet magnetized toward the fourth magnet 96d in the circumferential direction of the inner rotor 92.

[0062] In detail, the circumferentially magnetized magnets (first magnets) of the magnet group 96 on the inner circumferential surface of the inner rotor 92 are formed by a circumferentially magnetized magnet 96a that is magnetized in one direction of the inner rotor 92, for example clockwise, and a circumferentially magnetized magnet 96b that is magnetized in the other direction of the inner rotor 92, for example counterclockwise.

[0063] The fifth magnet is a magnet in which a circumferentially magnetized magnet 96a magnetized clockwise and a circumferentially magnetized magnet 96b magnetized counterclockwise are arranged such that their magnetization directions face toward the third magnet 96c in the circumferential direction of the inner rotor 92.

[0064] Furthermore, the sixth magnet is a magnet in which a circumferentially magnetized magnet 96a magnetized clockwise and a circumferentially magnetized magnet 96b magnetized counterclockwise are arranged such that their magnetization directions are oriented away from the fourth magnet 96d in the circumferential direction of the inner rotor 92.

[0065] It is preferable that the circumferentially magnetized magnets 96a, 96b and the radially magnetized magnets 96c, 96d are arranged alternately in the circumferential direction in a predetermined arrangement on the outer surface of the inner yoke 98.

[0066] The predetermined arrangement is a Halbach arrangement that concentrates the magnetic force radially outward from the inner yoke 98, and it is preferable that the third magnet, fifth magnet, fourth magnet 95d, and sixth magnet are repeatedly arranged in this order in the circumferential direction of the axis of the inner yoke 98.

[0067] More specifically, as shown in Figure 2, next to the radially magnetized magnet 96c, which is magnetized in the outer diameter direction, a circumferentially magnetized magnet 96a, which is magnetized clockwise, and a circumferentially magnetized magnet 96b, which is magnetized counterclockwise, are arranged with their magnetization directions directed toward the radially magnetized magnet 96c.

[0068] Furthermore, next to the radially magnetized magnet 96d, which is magnetized in the inner diameter direction, a circumferentially magnetized magnet 96a, which is magnetized clockwise, and a circumferentially magnetized magnet 96b, which is magnetized counterclockwise, are arranged so that the direction of magnetization is away from the radially magnetized magnet 96d.

[0069] This allows the inner rotor 92 to concentrate the magnetic force radially outward from the inner yoke 98.

[0070] In this way, the outer rotor 91 concentrates its magnetic force radially inward toward the outer yoke 97, and the inner rotor 92 concentrates its magnetic force radially outward toward the inner yoke 98, so the magnetic coupling 9 can increase the transmitted torque.

[0071] Furthermore, in the magnet group 95 arranged in the Halbach arrangement as described above, it is preferable that the circumferentially magnetized magnets 95a and 95b, which are magnetized in the circumferential direction of the outer rotor 91, are fitted into the recess 98a of the outer yoke 97.

[0072] Furthermore, in the magnet group 96 arranged in the Halbach arrangement as described above, it is preferable that the circumferentially magnetized magnets 96a and 96b, which are magnetized in the circumferential direction of the inner rotor 92, are fitted into the recess 98a of the inner yoke 98.

[0073] Furthermore, in the magnet group 95 arranged in the Halbach arrangement as described above, it is preferable that the ratio of the circumferential width of the outer yoke 97 of the circumferential magnetized magnets 95a and 95b, which are magnetized in the circumferential direction of the outer rotor 91, to the radially magnetized magnets 95c and 95d, which are magnetized in the radial direction of the outer rotor 91, is 1 / 2.

[0074] Furthermore, in the magnet group 96 arranged by the Halbach arrangement as described above, it is preferable that the ratio of the circumferential width of the outer yoke 97 of the circumferential magnetized magnets 96a and 96b, which are magnetized in the circumferential direction of the inner rotor 92, and the radially magnetized magnets 96c and 96d, which are magnetized in the radial direction of the inner rotor 92, is 1 / 2.

[0075] [Effect] The magnetic coupling 9 of this embodiment is a magnetic coupling that magnetically connects the output shaft 91 and the input shaft 92 via a partition wall 62 located between the output shaft 91 and the input shaft 92. The magnetic coupling includes magnet groups 95 and 96 provided on the opposing surface of one of the opposing surfaces 91c and 92a of the output shaft 91 and the input shaft 92. In the magnet groups 95 and 96, first magnets 95a, 95b, 96a, and 96b, which are magnetized in the circumferential direction of one of the shafts 91 and 92, and second magnets 95c, 95d, 96c, and 96d, which are magnetized in the radial direction of one of the shafts 91 and 92, are alternately arranged along the circumferential direction of one of the shafts 91 and 92. The thickness of the first magnets 95a, 95b, 96a, and 96b and the thickness of the second magnets 95c, 95d, 96c, and 96d are different in the radial direction of one of the shafts 91 and 92.

[0076] As a result, irregularities are formed in the magnet group by two types of magnets with different thicknesses in the radial direction of one of the shafts (output shaft 91 or input shaft 92). By engaging these irregularities with the one shaft, the occurrence of free rotation of the magnet group relative to the one shaft can be suppressed.

[0077] Furthermore, in this embodiment, the magnetic coupling 9 has a plurality of recesses 97b and 98a along the circumferential direction of one of the shafts 91 and 92, where the thicker magnets among the first magnets 95a, 95b, 96a, 96b and the second magnets 95c, 95d, 96c, 96d are fitted into the coupling portions 91d and 92b between one of the shafts 91 and 92 and the magnet groups 95 and 96, and it is preferable that the surfaces 91c and 92a formed by the magnet groups 95 and 96 that are located on the opposite side of the coupling portions 91d and 92b in the radial direction of one of the shafts form cylindrical sides.

[0078] As a result, the thicker magnets of the magnet groups 95 and 96 fit into the multiple recesses 97b and 98a, and by increasing the size of the magnets, the occurrence of free rotation of the magnet groups 95 and 96 relative to one of the shafts 91 and 92 can be suppressed. Therefore, compared to the case in which grooves or the like are provided on the magnets to suppress free rotation, the occurrence of free rotation of the magnet groups 95 and 96 relative to one of the shafts 91 and 92 can be suppressed without reducing the magnetic force or decreasing the transmitted torque. In addition, since the surfaces 91c and 92a located on the opposite side of the coupling portions 91d and 92b in the radial direction of one of the shafts form the cylindrical side surface, no irregularities are formed on the surfaces 91c and 92a, and the magnetic balance between the output shaft 91 and the input shaft 92 can be made uniform.

[0079] Furthermore, in this embodiment, the magnetic coupling 9 comprises first magnets 95a, 95b, 96a, 96b magnetized in the circumferential direction of one of the shafts 91, 92, and second magnets 95c, 95d, 96c, 96d magnetized in the radial direction of one of the shafts 91, 92. In this configuration, it is preferable that the magnets with greater thickness in the radial direction of one of the shafts 91, 92 are the first magnets 95a, 95b, 96a, 96b. This allows the magnetic flux to flow in the circumferential direction of one of the shafts 91, 92, thereby suppressing leakage flux.

[0080] Furthermore, in this embodiment, it is preferable that the magnetic coupling 9 has a double cylindrical structure at the magnetic coupling portion between the output shaft 91 and the input shaft 92. This allows the magnetic coupling 9 to be a coaxial magnetic coupling, and the magnetic poles are arranged concentrically, increasing the magnetic flux area and enabling efficient transmission of rotational torque.

[0081] Furthermore, in this embodiment, it is preferable that the magnetic coupling 9 has an output shaft 91 which is the output shaft of the electric motor 7, an input shaft 92 which is the driven shaft of the control rod 3, and a bulkhead 62 which is the reactor pressure vessel 4. This allows the control rod 3 to be moved up and down by the electric motor 7 outside the reactor pressure vessel 4, thereby ensuring high safety and coupling durability.

[0082] Furthermore, the magnetic coupling 9 in this embodiment is preferably a ball screw 53 whose driven shaft causes a ball nut 52 supporting the control rod 3 to move in a linear motion. This converts the rotation of the electric motor 7 into linear motion, allowing the control rod 3 to move up and down efficiently.

[0083] Furthermore, in this embodiment, the magnetic coupling 9 preferably has an annular fan shape for the cross-sectional shape of one axis 91, 92 of the first magnets 95a, 95b, 96a, 96b and the second magnets 95c, 95d, 96c, 96d, and a fan-shaped groove for the cross-sectional shape of one axis 91, 92 of the plurality of recesses 97b, 98a. As a result, it is not necessary to provide protrusions or the like for fitting into the recesses 97b, 98a of the first magnets 95a, 95b, 96a, 96b and the second magnets 95c, 95d, 96c, 96d, so the risk of the magnets being partially chipped can be suppressed.

[0084] Furthermore, in this embodiment, the magnetic coupling 9 preferably has first magnets 95a, 95b, 96a, 96b and second magnets 95c, 95d, 96c, 96d arranged in a Halbach arrangement, with the first magnets 95a, 95b, 96a fitted into recesses 97b, 98a.

[0085] Furthermore, the magnetic coupling 9 of this embodiment preferably has a second magnet 95c, 95d, 96c, 96d which includes a third magnet 95c, 96c magnetized toward the opposing surfaces 91c, 92a of the output shaft 91 and the input shaft 92, and a fourth magnet 95d, 96d magnetized toward the opposing surfaces 91c, 92a of the output shaft 91 and the input shaft 92, and a first magnet 95a, 95b, 96a, 96db, a fifth magnet magnetized toward the third magnet 95c, 96c in the circumferential direction of one of the shafts 91, 92, and a sixth magnet magnetized toward the fourth magnet 95d, 96d in the circumferential direction of one of the shafts 91, 92.

[0086] Furthermore, it is preferable that the Halbach arrangement consists of the third magnets 95c, 96c, the fifth magnets 95a, 95b, 96a, 96b, the fourth magnets 95d, 96d, and the sixth magnets 95a, 95b, 96a, 96b, repeated in this order on one axis 91, 92.

[0087] The effect of the magnetic coupling 9 with this configuration will be explained below with reference to the diagram.

[0088] Figure 5 is a schematic diagram showing the flow of magnetic flux in a part of the cross-section of the outer rotor 91 in which the circumferentially magnetized magnets 95a and 95b are fitted into the recess 97b of the outer yoke 97. Figure 6 is a schematic diagram showing the flow of magnetic flux in a part of the cross-section of the outer rotor 91 in which the radially magnetized magnet 95d is fitted into the recess 97b of the outer yoke 97.

[0089] As shown in Figure 5, when the circumferential magnetized magnets 95a and 95b, which are magnetized in the circumferential direction of the outer rotor 91, are fitted into the recess 97b of the outer yoke 97, the circumferential magnetized magnets 95a and 95b protrude radially outward from the outer yoke 97 more than the radial magnetized magnet 95d, which is magnetized radially outward from the outer rotor 91. Therefore, the magnetic flux flowing out radially outward from the circumferential end of the radial magnetized magnet 95d is absorbed by the protruding portions of the circumferential magnetized magnets 95a and 95b, as shown in Figure 5.

[0090] On the other hand, as shown in Figure 6, when the radially magnetized magnet 95d, which is magnetized on the radially outer side of the outer rotor 91, is fitted into the recess 97b of the outer yoke 97, the radially magnetized magnet 95d protrudes radially outward from the outer yoke 97 more than the circumferentially magnetized magnets 95a and 95b. Therefore, as shown in Figure 6, the magnetic flux flowing out radially from the circumferential end of the radially magnetized magnet 95d to the radially outer side of the outer yoke 97 is not absorbed by the circumferentially magnetized magnets 95a and 95b, but leaks out into the outer yoke 97.

[0091] Therefore, by increasing the radial thickness of the outer rotor 91 and fitting the circumferentially magnetized magnets 95a and 95b, which are magnetized in the circumferential direction of the outer rotor 91, into the recess 97b of the outer yoke 97, leakage magnetic flux can be suppressed.

[0092] This also applies to the inner rotor 92; an inner rotor 92 in which circumferentially magnetized magnets 96a and 96b are fitted into the recess 98a can reduce leakage flux more effectively than an inner rotor 92 in which circumferentially magnetized magnets 96c and 96d are fitted into the recess 98a.

[0093] Therefore, among the first magnets 95a, 95b, 96a, 96b and the second magnets 95c, 95d, 96c, 96d, which are arranged in a Halbach array, the first magnets 95a, 95b, 96a, 96b are fitted into the recesses 97b, 98a, thereby suppressing leakage flux and increasing the transmitted torque.

[0094] Furthermore, in this embodiment, it is preferable that the ratio of the circumferential width of one axis 91, 92 of the first magnets 95a, 95b, 96a, 96b and the second magnets 95c, 95d, 96c, 96d is 1 / 2. This allows the magnetic flux emitted from the clockwise-magnetized circumferential magnet 95a and the counterclockwise-magnetized circumferential magnet 95b toward the radially magnetized magnet 95c magnetized radially inward of the outer rotor 91 to be efficiently absorbed by the radially magnetized magnet 95c magnetized radially inward of the outer rotor 91.

[0095] Furthermore, in the inner rotor 92, the magnetic flux emitted from the clockwise-magnetized circumferential magnet 96a and the counterclockwise-magnetized circumferential magnet 96b toward the radial magnet 96c magnetized on the radially outer side of the inner rotor 92 can be efficiently absorbed by the radial magnet 96c magnetized on the radially outer side of the outer rotor 91. This further suppresses leakage flux and increases the transmitted torque.

[0096] Furthermore, in the control rod drive mechanism 1 using the magnetic coupling 9 of this embodiment, it is preferable that the output shaft 91 is the output shaft of the electric motor 7, the input shaft 92 is the driven shaft of the control rod 3, and the partition wall 62 is the reactor pressure vessel 4. As a result, the control rod drive mechanism 1 connects the output shaft of the electric motor 7 and the driven shaft of the control rod 3 via the partition wall 62, which is the reactor pressure vessel 4, using the magnetic coupling 9 of this embodiment, thereby ensuring high safety and coupling durability.

[0097] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0098] The embodiments of the present invention may also be as follows. For example, an embodiment in which the magnetic coupling 9 according to the present invention is used in a control rod drive mechanism 1 has been shown above. However, the invention is not limited to this and may be used in other industrial machines such as compressors.

[0099] 1...Control rod drive mechanism, 3...Control rod, 4...Reactor pressure vessel, 51...Hollow piston, 52...Ball nut, 53...Ball screw, 62...Bulkhead, 7...Electric motor, 9...Magnetic coupling, 91...Output shaft, 92...Input shaft, 91c, 92a...Opposite surfaces, 91d, 92b...Coupling parts, 95, 96...Magnet groups, 95a, 95b, 96a, 96b...First magnet, circumferentially magnetized magnet, fifth magnet, sixth magnet, 95c, 95d, 96c, 96d...Second magnet, radially magnetized magnet, 95c, 96c...Third magnet, 95d, 96d...Fourth magnet, 97b, 98a...Recess

Claims

1. A magnetic coupling that magnetically connects an output shaft and an input shaft via a partition wall located between the output shaft and the input shaft, comprising a group of magnets provided on the opposing surface of one of the opposing surfaces of the output shaft and the input shaft, wherein the group of magnets consists of a first magnet magnetized in the circumferential direction of the one shaft and a second magnet magnetized in the radial direction of the one shaft, which are alternately arranged along the circumferential direction of the one shaft, and the thickness of the first magnet and the thickness of the second magnet in the radial direction of the one shaft are different.

2. A magnetic coupling according to claim 1, wherein the coupling portion between the one shaft and the magnet group is provided along the circumferential direction of the one shaft, and the coupling portion between the one shaft and the magnet group is provided with a plurality of recesses into which the thicker of the first magnet and the second magnet is fitted, and the surface formed by the magnet group that is located on the opposite side of the coupling portion in the radial direction of the one shaft forms the side surface of a cylinder.

3. A magnetic coupling according to claim 1, characterized in that the magnet with the greater thickness in the radial direction of one of the first and second magnets is the first magnet.

4. A magnetic coupling according to claim 1, characterized in that the output shaft and the input shaft have a double cylindrical structure at the magnetic coupling portion.

5. A magnetic coupling according to claim 1, wherein the output shaft is the output shaft of an electric motor, the input shaft is the driven shaft of a control rod, and the partition is a reactor pressure vessel.

6. A magnetic coupling according to claim 5, characterized in that the driven shaft is a ball screw that causes a ball nut supporting the control rod to move in a linear motion.

7. A magnetic coupling according to claim 2, characterized in that the cross-sectional shape of the first magnet and the second magnet with respect to one axis is an annular fan shape, and the cross-sectional shape of the plurality of recesses with respect to one axis is a fan-shaped groove.

8. A magnetic coupling according to claim 2, characterized in that the first magnet and the second magnet are arranged in a Halbach arrangement, and the first magnet is fitted into the recess.

9. A magnetic coupling according to claim 8, wherein the second magnet has a third magnet magnetized in a direction toward the opposing surfaces of the output shaft and the input shaft, and a fourth magnet magnetized in a direction away from the opposing surfaces of the output shaft and the input shaft, the first magnet has a fifth magnet magnetized in a direction toward the third magnet in the circumferential direction of the one shaft, and a sixth magnet magnetized in a direction away from the fourth magnet in the circumferential direction of the one shaft, and the Halbach arrangement is characterized in that the third magnet, the fifth magnet, the fourth magnet, and the sixth magnet are repeatedly arranged in this order in the circumferential direction of the one shaft.

10. A magnetic coupling according to claim 8, characterized in that the ratio of the circumferential widths of one axis of the first magnet and the second magnet is 1 / 2.

11. A control rod drive mechanism using a magnetic coupling according to claim 1, characterized in that the output shaft is the output shaft of an electric motor, the input shaft is the driven shaft of a control rod, and the partition wall is a reactor pressure vessel.

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