JP4957891B2 - Synchronous motor - Google Patents

Description

  The present invention relates to a synchronous motor, for example, suitable for rotating a centrifugal impeller of a gas compression device at high speed, and particularly suitable for a motor that requires an output of several tens of kW or more at a rotational speed of about 30000 rpm or more.

  An induction motor is often used as a motor for driving a high-speed rotating body such as a centrifugal impeller of a compression device. However, induction motors generate heat based on resistance loss due to eddy currents generated in the rotor. Since the cooling method of the rotor that rotates at high speed is limited, it has been difficult to realize a high-power induction motor that generates a large amount of heat.

Therefore, it is considered that the high-speed rotating body is driven by a synchronous motor with a built-in permanent magnet (IPM motor). The IPM motor includes a stator having a coil for generating a rotating magnetic field and a rotor incorporating a permanent magnet, and the rotor rotates in synchronization with the rotation of the magnetic field generated by the coil (see Patent Document 1). In an IPM motor, the magnet torque generated by the attraction and repulsion between the magnetic field generated by the stator and the permanent magnet and the reluctance torque generated by the rotor's salient poles being attracted by the magnetic field generated by the stator are superimposed, making it compact and large. Torque can be output. 7A and 7B show a rotor 101 in a different conventional IPM motor, which includes a cylindrical yoke 102 made of a magnetic material and a plurality of permanent magnets 103. The yoke 102 is formed by stacking magnetic thin plates, and a shaft 104 for maintaining rigidity is inserted into a central hole of the yoke 102 so as to rotate along the same axis. A plurality of holes 102a are formed in the yoke 102 so as to be arranged in parallel along the rotation direction, and a permanent magnet 103 is fitted in each of the holes 102a. For example, when the number of poles of the motor is two, the side facing the stator 102 of the permanent magnet 103 arranged at the top in the figure is the N pole, and the side facing the stator 102 of the permanent magnet 103 arranged at the bottom is S. It is considered as a pole. Each permanent magnet 103 shown in FIG. 7A has an arc shape arranged on a circumference concentric with the rotation axis. Each permanent magnet 103 shown in FIG. 7B is not arranged on the circumference concentric with the rotation axis, and the reluctance torque generated by attracting the salient poles is increased.
JP 2006-217741 A

  When driving a high-speed rotating body with an IPM motor, it is desired to increase the generated torque. Therefore, the width of the yoke between the permanent magnets is reduced so that the magnetic torque generated by the permanent magnets passes through the magnetic path components on the stator side without waste, and the magnets between the magnetic poles of the permanent magnets are reduced. It is conceivable to reduce the passage magnetic flux. However, if the yoke width between the permanent magnets is reduced, the strength of the rotor decreases. In particular, the bending rigidity against resonance when passing through the critical speed when the rotational speed of the rotor changes cannot be secured, it is not possible to set a wide range of normal rotational speed, and management when the normal rotational speed exceeds the critical speed becomes difficult There is a problem of becoming. Furthermore, the breakage of the permanent magnet due to the action of a large centrifugal force during high-speed rotation becomes a problem. An object of this invention is to provide the synchronous motor which can solve such a problem.

The present invention includes a stator having a rotating magnetic field generating coil and a rotor incorporating a permanent magnet, wherein the rotor rotates in synchronization with rotation of a magnetic field generated by the coil, and the rotor includes the stator. And a magnetic material N pole yoke connected to the N pole side of the permanent magnet, and a magnetic material S pole yoke facing the stator and connected to the S pole side of the permanent magnet, A holding member made of a non-magnetic material that rotates along with the permanent magnet and the yokes, and the permanent magnet and the yokes are separated from each other by the N pole yoke and the S pole yoke. And is held by the holding member.
According to the present invention, since the N pole side and the S pole side of the permanent magnet are not connected via the yoke, the generated magnetic flux of the permanent magnet is guided to the vicinity of the outer periphery of the rotor via the yoke. It is possible to eliminate the magnetic path between the magnetic poles, reduce the useless magnetic flux, and increase the magnet torque. In addition, the salient pole structure that increases the reluctance torque of the yoke can be achieved.

  It is preferable that the permanent magnet is unevenly distributed in a region near the rotation axis of the rotor. Thereby, the action of the centrifugal force on the permanent magnet having a large specific gravity can be reduced, and the structure for the anti-centrifugal force can be simplified. Moreover, the mounting | wearing becomes easy by using a single permanent magnet.

When an in-plane bending moment including the rotation axis acts on the rotor, tensile stress acting on the outer periphery of the rotor becomes a problem in strength.
Therefore, as one feature of the present invention, the rotor is a non-magnetic reinforcing cylindrical member into which the permanent magnet, each yoke, and the holding member are inserted, and the holding member and the cylindrical member rotate together. A connecting mechanism for connecting to the cylindrical member, and the connecting mechanism applies a compressive force along the rotational axis direction to the cylindrical member so that a tensile stress based on bending acting on the outer periphery of the rotor is offset, and As a reaction of the compressive force, a tensile force along the rotation axis direction is applied to the holding member.
Alternatively, the rotor has a reinforcing cylindrical member made of a non-magnetic material into which the permanent magnet, each yoke, and the holding member are inserted, and a tensile load along the rotation axis direction is applied to the holding member. The holding member and the cylindrical member are welded so as to rotate together in at least one of a state and a state in which a compressive load along the rotation axis direction is applied to the cylindrical member. As a result, the compressive force along the rotation axis direction is applied to the cylindrical member so that the tensile stress due to the bending acting on the outer periphery of the rotor is offset, and as a reaction of the compressive force to the holding member. A tensile force along the rotational axis direction is applied.
Thereby, since the compressive stress is previously given to the cylindrical member which comprises the outer periphery of a rotor, the tensile stress based on the bending is canceled. That is, the tensile stress due to bending increases in proportion to the distance from the rotation axis that is the center of bending, but the maximum value of the tensile stress can be reduced by causing the cylindrical member to have a compressive stress in advance. Therefore, even if the displacement of the rotor increases due to resonance when passing through the critical speed when the rotational speed of the rotor changes, the bending stress at this time is suppressed to a level that does not cause damage, etc. There is no problem even if it can be set and the operating speed range exceeds the critical speed.

  When the holding member and the cylindrical member are connected by a connection mechanism, the holding member has one end located on one end side in the rotation axis direction, the other end located on the other end side in the rotation axis direction, and the one end portion. A connecting portion connecting the other end portion, a first screw portion formed concentrically with the rotation shaft at the one end portion, and a second screw portion formed concentrically with the rotation shaft at the other end portion. The permanent magnet is disposed in a space surrounded by the one end, the other end, and the connecting portion, and the connecting portion is disposed between the rotation directions of the N pole yoke and the S pole yoke. The connection mechanism includes a third screw portion that is screwed to the first screw portion, a fourth screw portion that is screwed to the second screw portion, and a third screw portion that is screwed to the first screw portion. A first pressing portion that presses one end of the cylindrical member by moving in the rotational axis direction; A fourth screw part to be screwed into the second screw part and a second pressing part that presses the other end of the cylindrical member by moving in the direction of the rotation axis, and the cylindrical member is pressed by both pressing parts. It is preferable that a compression force along the rotation axis direction is applied to the holding member, and a tensile force along the rotation axis direction is applied to the holding member as a reaction of the compression force. As a result, bending rigidity can be ensured by a structure that is easy to assemble.

  Furthermore, it is preferable that reinforcing fibers are wound in the circumferential direction on the outer periphery of the cylindrical member. As a result, the circumferential strength against hoop stress acting during high-speed rotation of the rotor can be improved.

  According to the present invention, it is possible to provide a high-speed, high-output synchronous motor capable of setting a wide range of normal rotation speeds.

  A pair of centrifugal impellers 2 a and 2 b in the centrifugal compressor 1 that compresses the process gas and the like shown in FIG. 1 is rotationally driven about a coaxial center by a synchronous motor 10 with a built-in permanent magnet. The motor 10 includes a rotor 11 and a stator 12 having a rotating magnetic field generating coil 12 a that covers the rotor 11. The rotary shafts 3 a and 3 b of the centrifugal impellers 2 a and 2 b are integrated with the rotor 11, and the scrolls 4 a and 4 b covering the centrifugal impellers 2 a and 2 b are integrated with the casing 5 covering the motor 10. The stator 12 is integrated. The motor 10 has three phases in this embodiment, and the coil 12a is connected to the drive inverter 13 of the motor 10 via a lead wire 12b. Labyrinth seals 7a and 7b are provided between the ceramic ball bearings 6a and 6b that support the rotating shafts 3a and 3b in the casing 5 and the centrifugal impellers 2a and 2b. When electric power is supplied to the motor 10 from an unillustrated power source via the inverter 13, the rotor 11 rotates in synchronization with the rotation of the magnetic field generated by the coil 12a. As a result, the gas introduced into the scrolls 4a and 4b by the centrifugal impellers 2a and 2b rotating at high speed is discharged from the scrolls 4a and 4b after being compressed and used by the process device.

  2 to 4B show the structure of the motor 10. The stator 12 may be formed by winding a coil 12 a around a thin laminate of magnetic materials, and may employ a known structure having a teeth portion 12 c that faces the rotor 11.

  The motor 10 of this embodiment has two poles, and the permanent magnet 20 built in the rotor 11 is single. The permanent magnet 20 of the present embodiment has a flat rectangular parallelepiped shape, and its long side is arranged along the rotation axis of the rotor 11 so that the rotation axis of the rotor 11 passes through the center of gravity. Thereby, the permanent magnet 20 is unevenly distributed in the region near the rotation axis of the rotor 11, and the N pole surface 20 a and the S pole surface 20 b of the permanent magnet 20 are parallel to the rotation axis of the rotor 11.

  The rotor 11 includes an N pole yoke 21a facing the stator 12 and connected to the N pole face 20a, an S pole yoke 21b facing the stator 12 and connected to the S pole face 20b, the permanent magnet 20 and Each of the yokes 21a and 21b has a holding member 22 that rotates together. Each yoke 21a, 21b is formed by laminating thin plates made of magnetic material, the connecting surface with the permanent magnet 20 and both end surfaces are flat surfaces, and the facing surface with the stator 12 is concentric with the rotation center of the rotor 11. The arc surface along the circle.

  The holding member 22 is made of a material that is non-magnetic, such as titanium, has a very high specific strength, and has a high electric resistance value among metals, and is one end located on one end side in the rotation axis direction. 22a, the other end portion 22b positioned on the other end side in the rotation axis direction, a connecting portion 22c connecting the one end portion 22a and the other end portion 22b, and a first screw formed concentrically with the rotation shaft at the one end portion 22a. The second end portion 22b has a second screw portion 22e formed concentrically with the rotating shaft and protruding outward in the axial direction. In the present embodiment, the one end 22a and the other end 22b are cylindrical, and the connecting portion 22c is composed of two portions 22c 'extending along the rotation axis direction, and both portions 22c' are arranged at equal intervals in the rotation direction. Is done. The outer peripheral surfaces of both end portions 22a and 22b and the connecting portion 22c are along a cylindrical surface centered on the rotation axis. In the present embodiment, the first screw portion 22d is a male screw and protrudes axially outward from the one end portion 22a, and the second screw portion 22e is a male screw and protrudes axially outward from the other end portion 22b. In the present embodiment, the first screw portion 22d is formed with a connecting female screw portion 22d 'for connection with the rotating shaft 3a, and the second screw portion 22e is formed with a connecting female screw portion 22e' for connection with the rotating shaft 3b.

  The permanent magnet 20 is disposed in a space surrounded by one end portion 22a, the other end portion 22b of the holding member 22 and the two portions 22c ′ of the connecting portion 22c, and is bonded to the holding member 22 with an adhesive, for example. The N pole yoke 21a and the S pole yoke 21b are connected to the permanent magnet 20 bonded to the holding member 22, and the yokes 21a and 21b are bonded to the holding member 22 with, for example, an adhesive. The outer peripheral surfaces of the yokes 21a and 21b and the outer peripheral surface of the holding member 22 form one cylindrical surface, and the connecting portion 22c is disposed between the rotation directions of the N pole yoke 21a and the S pole yoke 21b. Thereby, the permanent magnet 20 and each yoke 21a, 21b are hold | maintained by the holding member 22 in the state from which the yoke 21a for N poles and the yoke 21b for S poles were separated from each other.

  The rotor 11 includes a reinforcing cylindrical member 25 into which the permanent magnet 20, the yokes 21a and 21b, and the holding member 22 are inserted, and a connection mechanism 30 that connects the holding member 22 and the cylindrical member 25 so as to rotate together. The cylindrical member 25 is made of a nonmagnetic material having a high strength such as a titanium material. The connecting mechanism 30 applies a compressive force along the rotational axis direction to the cylindrical member 25, and a tensile force along the rotational axis direction is applied to the holding member 22 as a reaction of the compressive force.

  That is, the connection mechanism 30 includes a nut-like third screw portion 30a screwed to the first screw portion 22d, a fourth screw portion 30b screwed to the second screw portion 22e, a first pressing portion 30c, and a second It has a pressing part 30d. The first pressing portion 30c of the present embodiment is an annular shape having a center hole, a flange 30c ″ is formed on the outer periphery thereof, the first screw portion 22d is inserted in the center hole, and the outer periphery is an open end of the cylindrical member 25. The flange 30 c ″ is in contact with one end surface of the cylindrical member 25. The second pressing portion 30d of the present embodiment has an annular shape having a center hole, a flange 30d ″ is formed on the outer periphery thereof, the second screw portion 22e is inserted in the center hole, and the outer periphery is the other end of the cylindrical member 25. The flange 30 d ″ is inserted into the opening and is in contact with the other end surface of the cylindrical member 25. The first pressing portion 30c is disposed between the third screw portion 30a and the holding member 22 in the axial direction, and moves in the same direction as the third screw portion 30a to be screwed into the first screw portion 22d in the rotational axis direction. Press one end of 25. The second pressing portion 30d is disposed between the fourth screw portion 30b and the holding member 22 in the axial direction, and moves in the same direction as the fourth screw portion 30b to be screwed into the second screw portion 22e in the rotational axis direction. Press the other end of 25. By being pressed by both pressing portions 30c and 30d, a compressive force along the rotation axis direction is applied to the cylindrical member 25, and a tensile force along the rotation axis direction is applied to the holding member 22 as a reaction of the compression force. A reinforcing fiber 40 is wound around the outer periphery of the cylindrical member 25 in the circumferential direction. The reinforcing fiber 40 can be composed of, for example, high-strength fibers such as glass fiber, carbon fiber, and Tyranno fiber, and is preferably formed into an FRP layer by solidifying the reinforcing fiber 40 with a resin.

  According to the above embodiment, since the N pole side and the S pole side of the permanent magnet 20 are not connected via the yokes 21a and 21b, the magnetic flux generated by the permanent magnet 20 is transferred to the rotor via the yokes 21a and 21b. 11, the magnetic path between the magnetic poles of the permanent magnet 20 can be eliminated, the useless magnetic flux can be reduced, and the magnet torque can be increased. Further, the yokes 21a and 21b can have a salient pole structure that increases the reluctance torque. Since the permanent magnet 20 is unevenly distributed in the region near the rotation axis of the rotor 11, the action of the centrifugal force on the permanent magnet 20 having a large specific gravity can be reduced, and the structure for anti-centrifugal force can be simplified. Moreover, the mounting | wearing becomes easy by making the permanent magnet 20 into a single. Further, even if an in-plane bending moment including the rotation axis acts on the rotor 11, a compressive stress is applied in advance to the cylindrical member 25 constituting the outer periphery of the rotor 11, so that the tensile stress based on the bending is offset. The Therefore, when the rotation speed of the rotor 11 is changed, a wide range of normal rotation speeds can be ensured by ensuring that no excessive tensile stress acts even if the rotor 11 is bent due to resonance when passing through the critical speed. The area can be set, and there is no problem if the normal rotation speed exceeds the critical speed. In this case, it is possible to apply a compressive stress to the cylindrical member 25 in advance by simply screwing the third screw portion 30a with the first screw portion 22d and screwing the fourth screw portion 30b with the second screw portion 22e. Therefore, bending rigidity can be secured. Furthermore, the reinforcing fiber 40 is wound around the outer periphery of the cylindrical member 25 in the circumferential direction, so that the strength in the circumferential direction against hoop stress acting when the rotor 11 rotates at high speed can be improved.

  The present invention is not limited to the above embodiment. For example, the third screw portion and the first pressing portion in the above embodiment may be integrated, or the fourth screw portion and the second pressing portion may be integrated. Further, the first screw portion may be a female screw and the third screw portion may be a male screw, the second screw portion may be a female screw and the fourth screw portion may be a male screw.

  Moreover, it may replace with a connection mechanism like the said embodiment, and may weld so that a holding member and a cylindrical member may rotate together. That is, in the holding member 22 of the modified example shown in FIG. 5, the first screw portion 22d and the second screw portion 22e in the above-described embodiment are not formed, but instead from the one end portion 22a and the other end portion 22b. Projecting conical portions 22g and 22h are provided. The tips of the conical portions 22g and 22h are cylindrical portions 22g ′ and 22h ′, and internal thread portions for connecting to the rotating shafts 3a and 3b are formed on the inner circumferences of the cylindrical portions 22g ′ and 22h ′. The holding member 22 holding the permanent magnet 20 and the yokes 21a and 21b is inserted into the cylindrical member 25. In this inserted state, a tensile load is applied to the holding member 22 along the rotation axis direction, and the holding member 22 is held in a state in which this load is applied. The outer peripheral edge 22a 'of the one end 22a of the member 22 is welded to the inner peripheral edge 25' of the one end of the cylindrical member 25, and the outer peripheral edge 22b 'of the other end 22b is connected to the inner peripheral end of the other end of the cylindrical member 25 outside the figure. For example, welding is performed by electron beam welding. By removing the tensile load applied to the holding member 22 after the welding, a compressive force is applied to the cylindrical member 25 along the rotational axis direction, and the holding member 22 is reacted in the rotational axis direction as a reaction of the compressive force. A pulling force is applied. In addition, instead of or simultaneously with applying a tensile load along the rotation axis direction to the holding member 22 during welding, a compressive load along the rotation axis direction may be applied to the cylindrical member 25. The rest is the same as in the above embodiment.

  Further, the number of poles of the motor is not particularly limited, and may be four poles, for example. In this case, as shown in the modified examples of FIGS. 6A and 6B, the permanent magnet 20 has a rectangular parallelepiped shape when viewed in the rotation axis direction, and the N pole surface 20a and the S pole surface 20b are alternately arranged in the rotation direction. A pair of N pole yokes 21a and a pair of S pole yokes 21b are provided. Each of the yokes 21a and 21b has a flat surface facing the connection surface and both end surfaces of the permanent magnet 20 and the connecting portion 22c, and an arc along a circle whose concentric surface with the stator 12 is concentric with the rotation center of the rotor 11. It is considered as a surface. The connecting portion 22c of the holding member 22 includes four portions 22c ″ extending along the rotation axis direction, and the permanent magnet 20 is composed of one end portion 22a and the other end portion 22b of the holding member 22 and four portions 22c ″ of the connecting portion 22c. Arranged in the enclosed space. The rest is the same as in the above embodiment.

Structure explanatory drawing of the centrifugal compression apparatus provided with the synchronous motor of embodiment of this invention The partial exploded perspective view of the synchronous motor of the embodiment of the present invention The partial exploded perspective view of the rotor in the synchronous motor of the embodiment of the present invention Cross section of rotor in synchronous motor of embodiment of the present invention The longitudinal cross-sectional view of the rotor in the synchronous motor of embodiment of this invention The partial exploded perspective view of the rotor in the synchronous motor of the modification of this invention The partial exploded perspective view of the rotor in the synchronous motor of the other modification of this invention Cross-sectional view of a rotor in a synchronous motor of another modification of the present invention Cross section of rotor in conventional synchronous motor Cross section of different rotors in a conventional synchronous motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Synchronous motor 11 ... Rotor 12 ... Stator 12a ... Coil 20 ... Permanent magnet 21a ... N pole yoke 21b ... S pole yoke 22 ... Holding member 22a ... One end part 22b ... Other end part 22c ... Connection part 22d ... First Screw portion 22e ... Second screw portion 25 ... Cylindrical member 30 ... Connection mechanism 30a ... Third screw portion 30b ... Fourth screw portion 30c ... First pressing portion 30d ... Second pressing portion 40 ... Reinforcing fiber

Claims (5)

In a synchronous motor comprising a stator having a rotating magnetic field generating coil and a rotor containing a permanent magnet, the rotor rotating in synchronization with the rotation of the magnetic field generated by the coil,
The rotor is made of a magnetic material that is opposed to the stator and is connected to the N pole side of the permanent magnet, and a magnetic material N pole yoke that is opposed to the stator and is connected to the S pole side of the permanent magnet. An S pole yoke, and a permanent magnet and a holding member made of a non-magnetic material that rotates together with each yoke;
The permanent magnet and each yoke are held by the holding member in a state in which the north pole yoke and the south pole yoke are separated from each other,
The rotor includes a reinforcing cylindrical member made of a non-magnetic material into which the permanent magnet, each yoke, and the holding member are inserted, and a connection mechanism that connects the holding member and the cylindrical member so as to rotate together. Have
The connecting mechanism applies a compressive force along the rotational axis direction to the cylindrical member so that a tensile stress based on bending acting on the outer periphery of the rotor is offset, and as a reaction of the compressive force to the holding member in the rotational axis direction. A synchronous motor characterized by being given a tensile force along the axis. In a synchronous motor comprising a stator having a rotating magnetic field generating coil and a rotor containing a permanent magnet, the rotor rotating in synchronization with the rotation of the magnetic field generated by the coil,
The rotor is made of a magnetic material that is opposed to the stator and is connected to the N pole side of the permanent magnet, and a magnetic material N pole yoke that is opposed to the stator and is connected to the S pole side of the permanent magnet. An S pole yoke, and a permanent magnet and a holding member made of a non-magnetic material that rotates together with each yoke;
The permanent magnet and each yoke are held by the holding member in a state in which the north pole yoke and the south pole yoke are separated from each other,
The rotor has a reinforcing cylindrical member made of a nonmagnetic material into which the permanent magnet, each yoke, and the holding member are inserted,
The holding member and the cylinder in at least one of a state in which a tensile load along the rotation axis direction is applied to the holding member and a state in which a compression load along the rotation axis direction is applied to the cylindrical member The members are welded to rotate together,
When the load is removed after the welding, a compressive force along the rotation axis direction is applied to the cylindrical member so that a tensile stress based on bending acting on the outer periphery of the rotor is offset, and a reaction of the compressive force is performed. A pulling force along the rotational axis direction is applied to the holding member as a synchronous motor. In a synchronous motor comprising a stator having a rotating magnetic field generating coil and a rotor containing a permanent magnet, the rotor rotating in synchronization with the rotation of the magnetic field generated by the coil,
The rotor is made of a magnetic material that is opposed to the stator and is connected to the N pole side of the permanent magnet, and a magnetic material N pole yoke that is opposed to the stator and is connected to the S pole side of the permanent magnet. An S pole yoke, and a permanent magnet and a holding member made of a non-magnetic material that rotates together with each yoke;
The permanent magnet and each yoke are held by the holding member in a state in which the north pole yoke and the south pole yoke are separated from each other,
The rotor includes a reinforcing cylindrical member made of a non-magnetic material into which the permanent magnet, each yoke, and the holding member are inserted, and a connection mechanism that connects the holding member and the cylindrical member so as to rotate together. Have
A compression force along the rotation axis direction is applied to the cylindrical member by the connection mechanism, and a tensile force along the rotation axis direction is applied to the holding member as a reaction of the compression force,
The holding member has one end located on one end side in the rotation axis direction, the other end located on the other end side in the rotation axis direction, a connecting portion connecting the one end and the other end, and the one end A first screw portion formed concentrically with the rotating shaft, and a second screw portion formed concentrically with the rotating shaft at the other end portion,
The permanent magnet is disposed in a space surrounded by the one end portion, the other end portion, and the connecting portion,
The connecting portion is disposed between the rotation directions of the N pole yoke and the S pole yoke,
The connection mechanism includes a third screw portion screwed to the first screw portion, a fourth screw portion screwed to the second screw portion, a third screw portion screwed into the first screw portion, and a rotating shaft. The first pressing portion that presses one end of the cylindrical member by moving together in the direction and the fourth screw portion screwed into the second screw portion and the other end of the cylindrical member by pressing in the rotational axis direction A second pressing part,
By being pressed by both pressing portions, a compressive force along the rotation axis direction is applied to the cylindrical member, and a tensile force along the rotation axis direction is applied to the holding member as a reaction of the compression force. Synchronous motor. The synchronous motor according to claim 1, wherein the permanent magnet is unevenly distributed in a region near the rotation axis of the rotor. The synchronous motor according to any one of claims 1 to 4, wherein a reinforcing fiber is wound in a circumferential direction on an outer periphery of the cylindrical member.

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