JP2020156259A - Cylindrical linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular linear motor capable of improving mass thrust density. SOLUTION: In order to achieve the above object, a tubular linear motor M is arranged on a tubular armature E and an inner circumference of the armature E, and can move in the axial direction with respect to the armature E. It is provided with a field F in which N poles and S poles are alternately arranged in the axial direction, and a radialally magnetized annular main in which the field Fs are arranged alternately in the axial direction in a Halbach arrangement. It has a magnetic pole 8 and an annular sub-magnetic pole 10 magnetized in the axial direction, and an annular joint iron 9 provided on the armature E side of the main magnetic pole 8. [Selection diagram] Fig. 1

Description

The present invention relates to a tubular linear motor.

A tubular linear motor includes, for example, a tubular armature having a winding held on the inner circumference of a tubular yoke, a tubular rod inserted into the armature so as to be movable in the axial direction, and a shaft. Some include a plurality of permanent magnets that are laminated so that S poles and N poles appear alternately in the direction and are housed in the rod.

In the cylindrical linear motor configured in this way, for example, 120-degree energization control is performed in which a sinusoidal voltage shifted by 120 degrees is applied to the U-phase, V-phase, and W-phase windings of the armature. When the permanent magnet is attracted, the rod and the permanent magnet are driven axially with respect to the armature as a mover (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-086613

In a conventional cylindrical linear motor, permanent magnets are magnetized along the axial direction, and adjacent permanent magnets are stacked so that the same poles face each other, efficiently transmitting a magnetic field to the armature side. It is difficult to make it work, and there is a limit to improving the mass thrust density (the value obtained by dividing the maximum thrust of a tubular linear motor by the mass).

On the other hand, if the field is composed of a Halbach arrangement in which a main magnetic pole made of a permanent magnet magnetized in the radial direction and a secondary magnetic pole made of a permanent magnet magnetized in the axial direction are alternately laminated, an armature is used. It seems that the magnetic field can be concentrated on the side to improve the mass thrust density of the tubular linear motor, but if the axial length of the main magnetic pole is short, magnetic saturation occurs at the main magnetic pole and a large magnetic field is generated by the magnet. It is difficult to improve the mass thrust density because it cannot act on the magnet.

On the other hand, if the axial length of the main magnetic pole is sufficiently long enough not to cause magnetic saturation, the magnetic pole pitch becomes long, which not only increases the total length of the field in the axial direction, but also increases the length of the armature. Since the total length in the axial direction is also long, the mass is increased, and it is also difficult to improve the mass thrust density.

Therefore, an object of the present invention is to provide a tubular linear motor capable of improving the mass thrust density.

In order to achieve the above object, the tubular linear motor of the present invention is arranged on a tubular armature and on the inner or outer circumference of the armature and is movable in the axial direction with respect to the armature. It has a field magnet in which N poles and S poles are alternately arranged in the axial direction, and the field magnets are arranged in a Halbach arrangement in the axial direction alternately in the axial direction. It has a magnetized annular secondary magnetic pole and an annular joint iron provided on the armature side of the main magnetic pole.

In the cylindrical linear motor configured in this way, an annular joint iron is mounted on the outer circumference of the main magnetic pole on the armature side, so that the main magnetic pole does not have to be lengthened in the axial direction. Magnetic saturation is relaxed and more magnetic flux can be allowed to pass through. Therefore, even if the field of the Halbach array is used, a large magnetic field can be applied to the armature without lengthening the magnetic pole pitch. Therefore, the thrust can be improved by using the field due to the Halbach array without inviting an increase in the mass of the tubular linear motor.

Further, in the tubular linear motor, the field magnet is inserted on the inner peripheral side of the armature, the main magnetic pole is arranged on the inner peripheral side of the joint iron, and a plurality of magnet pieces divided in the circumferential direction are joined to form. It may have been. In the cylindrical linear motor configured in this way, since the main magnetic poles are formed by joining a plurality of magnet pieces, the main magnetic poles can be easily manufactured and scattered by the repulsion between the magnet pieces due to the joint iron on the outer circumference. Can be prevented. In addition, since the joint iron may be fitted on the outer circumference of the main magnetic pole, no screw fastening or other fastening structure is required to prevent the main magnetic pole from scattering, which simplifies the structure and reduces processing costs and increases mass. Can be suppressed.

According to the tubular linear motor of the present invention, the mass thrust density can be improved.

It is a vertical cross-sectional view of the cylindrical linear motor in one Embodiment. It is a top view of the main magnetic pole and the joint iron in one embodiment. It is a figure explaining the process of obtaining a magnet piece from a base material. (A) is a figure explaining a process of adhering four magnet pieces to the outer circumference of a rod. (B) is a figure explaining a process of adhering the remaining four magnet pieces to the outer periphery of a rod to form a main magnetic pole. It is a vertical cross-sectional view of the tubular linear motor in the 1st modification of one Embodiment.

Hereinafter, the present invention will be described based on the embodiments shown in the figure. As shown in FIG. 1, the tubular linear motor M in one embodiment is arranged on the inner circumference of the tubular armature E and the armature E, and can move in the axial direction with respect to the armature E. It is configured to include a field F in which north poles and south poles are alternately arranged in the axial direction.

Hereinafter, each part of the tubular linear motor M will be described in detail. The armature E is configured to include a tubular core 1 and a winding 2. The core 1 is configured to include a cylindrical core body 1a and a plurality of teeth 1b that are annular and are provided on the inner circumference of the core body 1a at intervals in the axial direction, and are fixed in the present embodiment. It is said to be a child.

As described above, the core 1 has a tubular shape, and as shown in FIG. 1, includes 10 teeth 1b provided on the inner circumference of the core main body 1a at equal intervals in the axial direction. A slot 3 formed by a gap in which the winding 2 is mounted is formed between 1b.

Further, in the present embodiment, a total of nine slots 3 formed as gaps are provided between the adjacent teeth 1b and 1b in FIG. 1. A winding 2 is wound around and mounted in the slot 3. The winding 2 is a U-phase, V-phase, and W-phase three-phase winding. In the nine slots 3, in order from the left side in FIG. 1, W phase, W phase, W phase and V phase, V phase, V phase, V phase and U phase, U phase, U phase and U phase and W phase. Winding 2 is attached. The arrangement of the phases of the winding 2 can be appropriately changed in relation to the number of magnetic poles on the field F side.

The armature E configured in this way is fixed to the inner circumference of the tubular case 4 and housed in the case 4. Further, the left end of the case 4 in FIG. 1 is connected to a tubular base 5 provided with a pair of trunnion pins 5a. The left end of the base 5 in FIG. 1 is connected to the open end of the bottomed tubular guide cylinder 6, and the case 4, the base 5, and the guide cylinder 6 form the outer shell of the tubular linear motor M. There is.

Further, the trunnion pins 5a and 5a in the base 5 have a tubular shape, and the inside and outside of the base 5 are communicated with each other through the inside of the trunnion pin 5a. Then, the winding 2 of each phase in the armature E is connected to a cord C1 which is inserted into one trunnion pin 5a and connected to a drive circuit (not shown) installed outside the tubular linear motor M. It receives power from the drive circuit. Further, a magnetic sensor S is provided in the base 5 to detect the magnetism of the field F, which will be described later, and detect the position (electrical angle) of the field F. The magnetic sensor S is connected to a signal line C2 that is inserted into the other trunnion pin 5a and connected to a controller that controls the drive circuit, detects the position of the field F, and signals a voltage to the controller. Is output. Since the cords C1 and C2 are led out of the tubular linear motor M from the hole provided in the center of the trunnion pin 5a, even if the tubular linear motor M swings around the trunnion pin 5a, the cords C1 and C1 C2 is not shaken, and the load on the codes C1 and C2 is reduced.

The field F has a main magnetic pole 8 made of an annular permanent magnet magnetized in the radial direction, an annular joint iron 9 mounted on the outer periphery of the main magnetic pole 8, and an annular magnetized in the axial direction. It is provided with an auxiliary magnetic pole 10 made of a permanent magnet of the above, and is formed by alternately laminating the main magnetic pole 8 and the auxiliary magnetic pole 10 so as to form a Halbach arrangement. The field F configured in this way is housed in an annular gap between the columnar rod 11 made of a non-magnetic material and the tubular cover 12 made of a non-magnetic material arranged on the outer circumference. ing. Specifically, the field F is adhered and fixed to the outer circumference of the rod 11.

The triangular marks on the main magnetic pole 8 and the sub magnetic pole 10 in FIG. 1 indicate the magnetizing direction, and as described above, the magnetizing direction of the main magnetic pole 8 is from the inner circumference to the outer circumference or from the outer circumference to the inner circumference. The direction of facing, that is, the radial direction, and the magnetizing direction of the sub-magnetic pole 10 is the axial direction. The magnetic poles of the main magnetic pole 8 and the sub magnetic pole 10 are arranged in a Halbach array, S poles and N poles appear alternately in the axial direction of the field F, and the magnetic field is an armature E on the outer periphery of the field F. It is arranged so that it works in a concentrated manner on the side.

An annular joint iron 9 is mounted on the outer circumference of the main magnetic pole 8 on the armature E side. That is, the main magnetic pole 8 is arranged on the inner peripheral side of the joint iron 9. The magnetic fluxes from the main magnetic pole 8 and the auxiliary magnetic pole 10 are focused on the joint iron 9, but the saturation magnetic flux density of the joint iron 9 is higher than the residual magnetic flux density of the main magnetic pole 8 and the auxiliary magnetic pole 10 which are permanent magnets. Therefore, a larger amount of magnetic flux can be passed to the magnet E side as compared with the case where the main magnetic pole 8 is arranged on the gap surface.

The inner diameters of the main magnetic pole 8 and the sub-magnetic pole 10 are the same, but the outer diameter of the main magnetic pole 8 is smaller than the outer diameter of the sub-magnetic pole 10. The outer diameter of the joint iron 9 is equal to the outer diameter of the secondary magnetic pole 10. Further, the axial length of the main magnetic pole 8 and the axial length of the joint iron 9 are made equal. Therefore, when the main magnetic pole 8 and the sub-magnetic pole 10 on which the joint iron 9 is mounted are laminated, the inner circumferences of the main magnetic pole 8 and the sub-magnetic pole 10 are flush with each other in the axial direction, and the outer circumference of the joint iron 9 and the sub-magnetic pole 10 Are flush with each other in the axial direction, and a cylindrical field F is formed. Further, the axial length of the main magnetic pole 8 is shorter than the axial length of the sub magnetic pole 10.

The rod 11 is a non-magnetic material and is made of a material having a specific gravity smaller than that of the main magnetic pole 8 and the sub magnetic pole 10 such as aluminum, and is inserted into the field F. The field F is fixed to the outer circumference of the rod 11 by adhesion and is held by the rod 11. Further, one end of the rod 11 is attached with a tip plug 14 to which an eye-shaped bracket 13 is connected, and the other end of the rod 11 is a terminal plug 16 that holds an annular slider 15 that is in sliding contact with the inner circumference of the guide cylinder 6. Is attached. The field F is sandwiched between the tip plug 14 and the end plug 16 to prevent misalignment with respect to the rod 11. Further, the cover 12 arranged on the outer circumference of the field F is sandwiched between the tip plug 14 and the end plug 16 and held by the rod 11. Further, an outer tube 17 that is in sliding contact with the outer periphery of the case 4 is attached to the tip plug 14. Therefore, the case 4, the outer tube 17, the guide cylinder 6, and the slider 15 guide the movement of the field F with respect to the armature E in the axial direction, and the field F is not eccentric with respect to the armature E. Can move smoothly in the direction.

The rod 11 protects the field F from the bending moment against the bending moment due to the external input. The cover 12 protects the field F by preventing the field F from interfering with the armature E when the field F is inserted into the armature E, but gives strength to the field F. It may have a function of protecting F from a bending moment. Further, one of the cover 12 and the rod 11 may be used as a strength member, and the other may be omitted.

Subsequently, in the present embodiment, the main magnetic pole 8 is formed by joining a plurality of arc-shaped magnet pieces MP in an annular shape as shown in FIG. Specifically, the main magnetic pole 8 is formed by joining eight arc-shaped magnet pieces MP. That is, in the present embodiment, the main magnetic pole 8 is composed of magnet pieces MP that are evenly divided into eight in the circumferential direction, and eight arc-shaped magnet pieces MP having the same shape are combined in an annular shape to form each. Both ends of the magnet piece MP in the circumferential direction are bonded to each other with an adhesive, and these are joined to form an integral body. In FIG. 2, the ▲ mark indicates the direction of magnetism. Further, FIG. 2 shows an example in which the magnetizing direction is inward in the radial direction, the outer peripheral side is the S pole and the inner peripheral side is the N pole, but when the outer peripheral side is the N pole and the inner peripheral side is the S pole. The magnetizing direction may be outward in the radial direction.

As shown in FIG. 2, each magnet piece MP is magnetized in a parallel orientation, and is magnetized with a magnetic pole pattern in which different magnetic poles appear on the inner circumference and the outer circumference. In this case, the main magnetic pole 8 has a magnetic pole pattern in which one of the N pole and the S pole appears on the inner peripheral side and the other of the N pole and the S pole appears on the outer peripheral side. Although each magnet piece MP is magnetized in parallel orientation, since the magnetic orientation directions of the plurality of magnet pieces MP are joined so as to face the center of the main magnetic pole 8, the main magnetic pole 8 has a pseudo radial orientation. Can function as a magnet.

Since the main magnetic pole 8 is formed by joining the magnet pieces MP, the center of curvature O on the inner and outer circumferences of the magnet piece MP when viewed in the axial direction is the main magnetic pole 8 if dimensional errors and processing errors are ignored. It becomes the same point as the center of.

In order to manufacture such a main magnetic pole 8, first, as shown in FIG. 3, a rectangular parallelepiped is used as a base material B, and the base material B is magnetized in a parallel orientation with the lateral direction as the magnetic orientation direction. The arrow indicated by the alternate long and short dash line in FIG. 3 indicates the magnetic orientation direction. The base material B is obtained, for example, by molding a raw material suitable for a magnet into a rectangular parallelepiped by sintering or casting. The base material B magnetized in parallel orientation is processed into an arc shape by cutting off a portion other than the portion required as the magnet piece MP shown by the broken line in FIG. 3 by cutting or the like to create the magnet piece MP.

In the process of creating the magnet piece MP from the base material B, the center of curvature O on the inner and outer circumferences of the magnet piece MP to be obtained is arranged on a line extending from an arbitrary point of the base material B in the magnetic orientation direction. Is machined to form the inner and outer circumferences. When the cutting process is performed in this way, the magnetic orientation direction at the center of the completed magnet piece MP is toward the center of the main magnetic pole 8, which is advantageous in terms of magnetic strength. As described above, in the present embodiment, the line connecting the center of the magnet piece MP and the center of curvature O of the magnet piece MP corresponding to the center of the main magnetic pole 8 (two-point chain line in FIG. 3) and the circumferential direction of the magnet piece MP It matches the direction of magnetic orientation in the center of. In this way, if the line connecting the center of the magnet piece MP in the circumferential direction and the center of the main magnetic pole 8 and the magnetic orientation direction of the center of the magnet piece MP are matched, the magnetic strength can be efficiently increased. That is, when each magnet piece MP is magnetized with the direction connecting the center of the circumferential direction of each magnet piece MP and the center of curvature O of the inner and outer circumferences of the magnet piece as the magnetic orientation direction, the magnetic strength can be efficiently increased. .. It is preferable that the line connecting the center of the magnet piece MP in the circumferential direction and the center of the main magnetic pole 8 and the magnetic orientation direction of the center of the magnet piece MP match, but the inner circumference and the outer circumference of the magnet piece MP differ from each other. It suffices if it is magnetized so that

In order to form the main magnetic pole 8 by joining the magnet pieces MP produced in this manner in an annular shape, the magnet pieces MP are processed as follows in the present embodiment. First, as shown in FIG. 4A, the four magnet pieces MP are bonded to the outer periphery of the rod 11 so as to be arranged at equal intervals in the circumferential direction (first step). Then, after the adhesive is sufficiently dried and the four magnet piece MPs are fixed to the rod 11, as shown in FIG. 4 (b), the remaining four magnet pieces MP are already roded while interposing the adhesive. It is fitted between the magnet pieces MP fixed to No. 11 and adhered (second step). When the rod 11 is used as the core material in this way, the magnet piece MP can be easily joined in an annular shape, the processing for manufacturing the main magnetic pole 8 can be simplified, and the magnet piece MP can be fixed to the rod 11 at the same time. Therefore, if the main magnetic pole 8 is formed and then bonded to the rod 11, a bonding step between the main magnetic pole 8 and the rod 11 is required. However, if the magnet piece MP is bonded to the rod 11 to form the main magnetic pole 8, the bonding step is required. The processing cost is reduced because it can be omitted.

After the magnet piece MP is attached to the outer periphery of the rod 11 to form the main magnetic pole 8 in this way, the joint iron 9 is fitted and adhered to the outer periphery of the main magnetic pole 8 (third step). Then, when the main magnetic pole 8 and the joint iron 9 are integrated, the sub magnetic pole 10 is subsequently laminated on the main magnetic pole 8 and the joint iron 9 and bonded to each other (fourth step). When the auxiliary magnetic pole 10 is sufficiently fixed, the steps of the first step to the fourth step described above are repeated. This process is repeated until the number of magnetic poles required for the tubular linear motor M is satisfied, and the field F is formed.

The main magnetic pole 8 manufactured in this manner behaves as a magnet magnetized in a radial orientation, although the magnet piece MP is aligned in parallel. As shown in FIG. 2, assuming that the angle α formed by the magnetic orientation direction at an arbitrary point of each magnet piece MP with the diameter direction of the main magnetic pole 8 when viewed in the axial direction is 25 degrees or less, each magnet piece MP is aligned in parallel. Although magnetized with, the main magnetic pole 8 approaches the radial orientation, and the field strength on the inner peripheral side can be secured. According to the main magnetic pole 8, the decrease in field strength is kept low as compared with the annular magnet having a perfect radial orientation, so that the field strength comparable to that of the annular magnet having a perfect radial orientation can be secured. The number of magnet pieces MP forming the main magnetic pole 8, that is, the number of divisions of the main magnetic pole 8 is eight in the present embodiment, but is not limited to eight.

The shape of the magnet pieces MP does not have to be the same, but in the present embodiment, all the magnet pieces MP have the same shape. When the shape of the magnet piece MP is the same as described above, there is no concern that a portion of the main magnetic pole 8 having a particularly low magnetic strength will be randomly formed. Further, if the circumferential lengths of the magnet pieces MP are not uniform, a beautiful annular ring can be formed when joining them, which makes the joining process troublesome. However, if the magnet pieces MP have the same shape, they are joined. Processing is also easy.

Although the main magnetic pole 8 is mounted on the outer circumference of the rod 11 in the present embodiment, the rod 11 can be abolished. In that case, the main magnetic pole 8 and the sub magnetic pole 10 may be formed in a disk shape instead of an annular shape, and the cover 12 may be provided with strength to protect the field F so that the force for bending the field F does not act. Good. Further, although the main magnetic pole 8 is formed by a plurality of magnet pieces MP divided in the circumferential direction, it may be a single disk-shaped or annular permanent magnet. In the present embodiment, the main magnetic pole 8 is made of a material containing neodymium, iron, and boron as main components and has a high residual magnetic flux density, and the auxiliary magnetic pole 10 is an amount of a heavy rare earth element such as dysprosium or teribium added to the material. It is composed of magnets that are difficult to demagnetize.

In the cylindrical linear motor M configured in this way, the position of the field F with respect to the armature E is detected by the magnetic sensor S, the current-carrying phase is switched based on the electric angle, and each winding 2 is controlled by PWM. The amount of current can be controlled to control the thrust and the moving direction of the field F with respect to the armature E. The above-mentioned control method is an example and is not limited to this. As described above, in the tubular linear motor M of the present embodiment, the armature E is a stator and the field F behaves as a mover. Further, in the tubular linear motor M, when an external force that relatively displaces the armature E and the field F in the axial direction acts, the winding 2 is energized or the induced electromotive force generated in the winding 2 causes the tubular linear motor M. It is possible to generate a thrust that suppresses the relative displacement, suppress the relative displacement between the armature E and the field F, and regenerate energy that generates electric power from an external force.

As described above, the tubular linear motor M of the present embodiment is arranged on the inner circumference of the tubular armature E and the armature E, and is movable in the axial direction with respect to the armature E. An annular main magnetic pole 8 provided with a field F in which N poles and S poles are alternately arranged in the axial direction, and the field Fs are arranged alternately in the axial direction in a Halbach arrangement. It also has an annular sub-magnetic pole 10 magnetized in the axial direction and an annular joint iron 9 provided on the armature E side of the main magnetic pole 8.

In the tubular linear motor M configured in this way, an annular joint iron 9 is mounted on the outer periphery of the main magnetic pole 8 on the armature E side, so that the axial length of the main magnetic pole 8 is increased. Even if this is not done, the magnetic flux from the secondary magnetic pole 10 is focused, and more magnetic flux can be allowed to pass through. Therefore, even if the field F of the Halbach array is used, a large magnetic field can be applied to the armature E without lengthening the magnetic pole pitch. Therefore, the thrust can be improved by using the field F in the Halbach array without inviting an increase in the mass of the tubular linear motor M. From the above, according to the tubular linear motor M of the present embodiment, the mass thrust density can be improved.

In the tubular linear motor M of the present embodiment, the armature E is arranged on the outer periphery of the field F, but like the tubular linear motor MA shown in FIG. 5, the tubular field FA The armature EA may be arranged on the inner circumference of the armature. The directions of the magnetic poles of the main magnetic pole 8A and the sub magnetic pole 10A in the field FA may be arranged so that the magnetic field acts concentrated on the armature EA side of the inner circumference. In that case, a joint iron 9A is provided on the inner circumference of the main magnetic pole 8A on the armature EA side, and the secondary magnetic poles 10A are alternately laminated on the integrated main magnetic pole 8A and the joint iron 9A to form a field FA. do it. As for the armature EA, a lot 3A may be provided on the outer periphery of the core 1A, and windings 2A of each phase may be mounted in the slot 3A. Even in the tubular linear motor MA in which the armature EA is inserted in the inner circumference of the field FA so as to be movable in the axial direction, the length in the axial direction is long because the joint iron 9A is provided in the inner circumference of the main magnetic pole 8A. Since the magnetic flux from the secondary magnetic pole 10 is focused without increasing the length, the thrust can be secured without increasing the mass, and the mass thrust density can be improved.

Further, in the tubular linear motor M of the present embodiment, the field F is inserted on the inner peripheral side of the armature E, and the main magnetic pole 8 is formed by joining a plurality of magnet pieces MP divided in the circumferential direction. Has been done. In the tubular linear motor M configured in this way, the main magnetic pole 8 is arranged on the inner peripheral side of the joint iron 9 and is formed by joining a plurality of magnet pieces MP, so that the main magnetic pole 8 can be easily manufactured. At the same time, it is possible to prevent scattering due to repulsion between the magnet pieces MP by the joint iron 9 on the outer circumference. Further, since the joint iron 9 may be fitted to the outer periphery of the main magnetic pole 8, no screw fastening or other fastening structure is required to prevent the main magnetic pole 8 from scattering, so that the structure is simplified and the processing cost is reduced. The mass increase can be suppressed.

Further, in the tubular linear motor M of the present embodiment, since the main magnetic pole 8 and the sub magnetic pole 10 are annular, the weight is lighter than that of using the main magnetic pole 8 and the sub magnetic pole 10 as a disk-shaped magnet, and the tubular linear motor is linear. The mass thrust density of the motor M can be further improved.

Further, in the tubular linear motor M of the present embodiment, the field F is mounted on the outer periphery of the rod 11 made of a material having a specific gravity smaller than that of the main magnetic pole 8 and the sub magnetic pole 10. In the tubular linear motor M configured in this way, the rod 11 can be used as a core material when a plurality of magnet pieces MP are joined to form the main magnetic pole 8, so that the magnet pieces MP are joined in an annular shape. The increase in mass of the tubular linear motor M can be suppressed even if the rod 11 is provided. Although the rod 11 has a solid columnar shape, it may have a tubular shape.

Although the preferred embodiments of the present invention have been described in detail above, modifications, modifications, and changes can be made without departing from the scope of the claims.

8,8A ... Main magnetic pole, 9,9A ... Joint iron, 10,10A ... Secondary magnetic pole, 11 ... Rod, E, EA ... Armature, F, FA ... Field , M, MA ・ ・ ・ Cylindrical linear motor, MP ・ ・ ・ Magnet piece

Claims (2)

With a tubular armature
It is provided with a field that is arranged on the inner circumference or the outer circumference of the armature, is movable in the axial direction with respect to the armature, and has N poles and S poles alternately arranged in the axial direction.
The fields are arranged on the axially magnetized annular main magnetic poles and the axially magnetized annular secondary magnetic poles arranged alternately in the axial direction in a Halbach array, and on the armature side of the main magnetic poles. A tubular linear motor characterized by having an annular joint iron provided. The field is inserted into the inner peripheral side of the armature.
The tubular linear motor according to claim 1, wherein the main magnetic pole is arranged on the inner peripheral side of the joint iron and is formed by joining a plurality of magnet pieces divided in the circumferential direction.

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