JP5991841B2 - Cylindrical linear motor - Google Patents

Description

  The present invention relates to a linear motor, and more particularly to a cylindrical linear motor.

In recent years, in electronic component mounting apparatuses, in order to improve mounting speed and accuracy, the combination of a ball screw and a rotary servo motor, which has been conventionally used as an actuator for driving a nozzle, has been replaced with a cylindrical linear motor. .
As a configuration of the cylindrical linear motor, for example, as in Patent Document 1, there is one in which a mover is configured by inserting a plurality of permanent magnets into a pipe.
Moreover, there exists a linear motor of the structure which does not use a permanent magnet for a needle | mover like patent document 2, for example. This is called a cylindrical linear pulse motor, and a plurality of fine teeth are formed on the surface of the mover, and fine teeth with the same pitch are also formed inside the stator.

JP 2008-79358 A JP-A-7-39135

  The thing of the said patent document 1 had a problem that it was necessary to extend a needle | mover when a long stroke was required, and the number of permanent magnets needed to be increased in connection with it, and the cost increased.

Further, the one of Patent Document 2 has a configuration of a stepping motor, and the positioning accuracy of the mover depends on the teeth pitch. Therefore, in order to increase the accuracy, it is necessary to make the teeth pitch fine. In the case of a mounting device in which a nozzle is attached to the tip of a stepping motor, considering productivity, it is necessary to arrange a plurality of units in close proximity, and for this purpose, a cross section of the linear motor (with respect to the axis of the mover) It is important that the cross-sectional shape when cut along the vertical direction is small.
However, in the thing of patent document 2 in which the several fine teeth were formed in the needle | mover surface, there existed a problem that it was difficult to achieve high precision, reducing in size.

  An object of the present invention is to provide a cylindrical linear motor that can solve such problems and is inexpensive, can be miniaturized, and can be highly accurate even with a long stroke. To do.

A cylindrical linear motor according to the present invention is provided so that it can reciprocate along the central axis relative to the armature by the interaction between the cylindrical armature and the central axis of the armature. Field element,
The armature has a plurality of ring-shaped phase coils arranged at intervals along the axial direction, and a permanent magnet portion made of a ring-shaped permanent magnet provided between the phase coils,
The field element has a shaft, and a ring-shaped salient pole made of a magnetic material arranged in a plurality at intervals along the axis of the shaft,
The salient pole has a total number of 5n when n is an integer equal to or greater than 1, and the phase coil facing the salient pole has a total number of 6n.
The three-phase coils are arranged at least once in the order of U + phase, U− phase, V + phase, V− phase, W + phase, and W− phase along the axial direction .
The adjacent permanent magnet portions are magnetized in the axial direction so as to have different polarities .

According to the cylindrical linear motor of the present invention, by arranging both the phase coil and the permanent magnet portion in the armature, when the stroke is increased, the number of salient poles of the field element may be increased. Since the number of permanent magnet parts does not need to be increased, the cost is reduced.
In addition, the control is not a stepping motor system, but the same control as a general linear servo motor is possible, and the positioning accuracy of the field element does not depend on the salient pole pitch, so high accuracy can be achieved even when miniaturized. It is.

It is a sectional side view which shows the cylindrical linear motor in Embodiment 1 of this invention. It is a disassembled perspective view which shows the needle | mover of FIG. It is a coil magnetic flux waveform of the cylindrical linear motor of FIG. It is another coil magnetic flux waveform of the cylindrical linear motor in Embodiment 1 of this invention. It is a winding figure of the Y connection of the cylindrical linear motor in Embodiment 1 of this invention. It is a winding figure of other Y connection of the cylindrical linear motor in Embodiment 1 of this invention. FIG. 3 is a winding diagram of Δ connection of the cylindrical linear motor according to the first embodiment of the present invention. It is a winding figure of other delta connection of the cylindrical linear motor in Embodiment 1 of this invention. It is a sectional side view which shows the modification of the cylindrical linear motor in Embodiment 1 of this invention. It is a sectional side view which shows the other modification of the cylindrical linear motor in Embodiment 1 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 2 of this invention. It is a sectional side view which shows the modification of the cylindrical linear motor in Embodiment 2 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 3 of this invention. It is a perspective view which shows the permanent magnet part and coil in Embodiment 3 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 4 of this invention. It is a sectional side view which shows the modification of the cylindrical linear motor in Embodiment 4 of this invention. It is a sectional side view which shows the cylindrical linear motor which shows the other modification in Embodiment 4 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 5 of this invention. It is a sectional side view which shows the modification of the cylindrical linear motor in Embodiment 5 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 6 of this invention. It is a sectional side view which shows the modification of the cylindrical linear motor in Embodiment 6 of this invention. It is a sectional side view which shows the cylindrical linear motor in Embodiment 7 of this invention. It is a perspective view which shows the needle | mover of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
FIG. 1 is a side sectional view showing a cylindrical linear motor (hereinafter abbreviated as a linear motor) according to Embodiment 1 of the present invention.
The linear motor of this embodiment includes a cylindrical frame 1, a stator 2 that is a cylindrical armature fixed to the inner wall surface of the frame, and a central axis disposed on the central axis of the stator 2. And a mover 3 that is a field element that reciprocates on the wire.

The stator 2 is a stator core that is an armature core that covers three surfaces excluding the ring-shaped phase coil 4 arranged along the axial direction and the facing surface side of the phase coil 4 facing the mover 3. 5 and a permanent magnet portion 6 made of a plurality of ring-shaped permanent magnets arranged between adjacent stator cores 5 and on both sides.
The stator core 5 is made of a magnetic material such as iron, an electromagnetic steel plate, or a dust core. Adjacent permanent magnet portions 6 are magnetized in the axial direction so as to have different polarities.
The permanent magnet section 6 is preferably a neodymium magnet in order to improve the thrust characteristics as a permanent magnet, and a ferrite magnet is preferably used in order to reduce the cost.
The phase coil 4 may be manufactured by being wound around a jig and integrated with a varnish or a mold and then removed from the jig, or may be manufactured by winding a copper wire around a bobbin-shaped insulator.
About the edge part of the axial direction of the stator core 5, in order to reduce cogging force, another shape may be sufficient.

The mover 3 includes a shaft 9 made of a magnetic material, and a plurality of ring-shaped salient poles 10 arranged on the shaft 9 at intervals in the axial direction.
As shown in FIG. 2, the mover 3 may be formed by processing a plurality of salient poles 10 that are ring-shaped magnetic bodies, and fixing them through a shaft 9 by bonding or welding.
Alternatively, it may be manufactured by a lathe process from a material that is a cylindrical magnetic material.
The tip of the shaft 9 may be made of a non-magnetic material so as not to cause a magnetic problem in order to attach a nozzle and attract electronic components.

The cylindrical stator 2 is fixed in the frame 1 by shrink fitting or adhesion.
The mover 3 is supported by a bearing 11 such as a linear bush fixed to both ends of the frame 1 so as to be linearly movable.
Since the magnetic flux from the permanent magnet portion 6 leaks to the frame 1 and the characteristics are deteriorated, the frame 1 is preferably composed of a nonmagnetic material such as aluminum or SUS.
The axial length of the frame 1 is equal to the axial length of the stator 2 and the stroke length S of the movable element 3 (see FIG. 1) in order to ensure the movement of the movable element 3 in the linear motion direction. More than doubled value is required.

Next, the relationship between the phase coil 4 and the salient pole 10 will be described.
As shown in FIG. 1, for example, six phase coils 4 are opposed to five salient poles 10, and the arrangement of the phase coils 4 of each phase is arranged along the axis of the stator 2 with a U + phase , U When the -phase , V + phase , V-phase , W + phase , and W-phase are selected, the coil magnetic flux waveform shown in FIG. 3 is obtained. In addition, as for + phase of each phase and-phase, the winding of a copper wire shows a reverse direction.
At this time, the electrical angle of 360 ° corresponds to the salient pole pitch. Since the magnetic flux of the three-phase winding is balanced at an electrical angle of 360 ° and the phase is shifted by 120 °, it can be driven by the same control as a general linear servomotor.

Further, the number of salient poles 10 and phase coils 4 is the same as the above with five salient poles 10 and six phase coils 4, and the arrangement of each phase coil 4 of the three-phase winding is the stator. When the U + phase , the V + phase , the W + phase , the U + phase , the V + phase , and the W + phase are set along the axis 2, the coil magnetic flux waveform shown in FIG. 4 is obtained.
Since the magnetic flux of the three-phase windings is balanced and the phase is shifted by 120 °, the arrangement of this phase coil 4 can be controlled in the same manner, but the peak value is increased compared to that of FIG. Therefore, the arrangement of the phase coil 4 in FIG. 4 can obtain a larger thrust with the same current.

The arrangement of each phase coil 4 and the connection method may be Y connection or Δ connection.
Fig. 5 shows the winding diagram of the three-phase winding when the arrangement of the phase coil 4 is U + phase , U- phase , V + phase , V-phase , W + phase , W + phase and Y connection. FIG. 6 shows a winding diagram of a three-phase winding when the arrangement of 4 is a U + phase , a V + phase , a W + phase , a U + phase , a V + phase , and a W + phase and a Y connection.
Further, FIG. 7 shows a winding diagram of a three-phase winding when the phase coil 4 is arranged in the U + phase , U− phase , V + phase , V− phase , W + phase , W− phase and Δ connection. FIG. 8 shows a winding diagram of a three-phase winding when the phase arrangement of the phase coil 4 is U + phase , V + phase , W + phase , U + phase , V + phase , W + phase and Δ connection.
In the case of the one shown in FIG. 7, the winding direction is changed alternately for each phase coil 4 so that the copper wire is continuously wound and the lead wire is connected between the phase coils 4. .
In the case of the one shown in FIG. 8, all six phase coils 4 are continuously wound with copper wires in the same direction, and lead wires are connected between the phase coils 4 so that the connection work of the copper wires is simplified. .

According to the linear motor having the above configuration, both the phase coil 4 and the permanent magnet portion 6 are arranged on the stator 2, and the number of salient poles 10 of the mover 3 may be increased even when the stroke is increased. Therefore, it is not necessary to increase the number of permanent magnet portions 6, and thus the cost of the linear motor is reduced.
Further, the control is the same as that of a general linear servo motor, and the positioning accuracy of the mover 3 does not depend on the pitch of the salient poles 10, so that high accuracy can be achieved even when the size is reduced.

  In addition, in the case of a conventional mover in which a plurality of permanent magnet parts are inserted into a pipe and the structure is such that the permanent magnet part enters and exits from the frame, there is a problem of magnetic interference with an adjacent linear motor. In this embodiment, the permanent magnet part 6 is not used for the mover 3 and the permanent magnet part does not enter and exit from the frame 1, so that magnetic interference with the adjacent linear motor is reduced.

FIG. 9 is a side sectional view showing a modification of the linear motor in the first embodiment.
In this example, each stator core 5 is divided into a core back portion 7 and a ring-shaped tooth portion 8.

FIG. 10 is a side sectional view showing another modification of the linear motor in the first embodiment.
Also in this example, each stator core 5 is divided into a core back portion 7 and a ring-shaped tooth portion 8 as in FIG. 9, but the outer peripheral surface of the teeth portion 8 faces the frame 1. Compared with the thing of FIG. 9, the dimension of the radial direction of the teeth part 8 is large, and the length of the axial direction of the core back part 7 is short compared with the thing of FIG.
In any case, the stator core 5 shown in FIG. 1 has a ring shape in which a concave portion is formed on the inner diameter side and is difficult to process. However, in the stator core 5 shown in FIGS. The core back portion 7 and the ring-shaped tooth portion 8 are divided, and the stator core 5 can be easily manufactured.

Embodiment 2. FIG.
FIG. 11 is a side sectional view showing a linear motor according to Embodiment 2 of the present invention.
In this linear motor, the stator core 5 is constituted only by the teeth portion 8 and there is no core back portion 7.
FIG. 12 is a modification of FIG. 11. In this example, the stator core 5 is composed only of the core back portion 7, and there is no tooth portion 8. Permanent magnet portions 6 are interposed between the phase coils 4, and the permanent magnet portions 6 are defined between the phase coils 4.
Other configurations are the same as those of the linear motor of the first embodiment.

The stator core 5 according to the first embodiment surrounds three surfaces of the phase coil 4, of which the stator core 4 shown in FIG. 1 is difficult to process, and the stator core shown in FIGS. 9 and 10 is the stator. The core 5 is divided into the core back part 7 and the teeth part 8, and the number of parts is large.
On the other hand, in this embodiment, the core back part 7 or the teeth part 8 of the stator core 5 is deleted, the number of parts is reduced, the assembly cost is reduced, and the deleted part is the phase coil 4. By occupying, the cross-sectional area of the phase coil 4 can be increased.

Embodiment 3 FIG.
13 is a side sectional view showing a linear motor according to Embodiment 3 of the present invention, and FIG. 14 is an exploded perspective view of the stator 2 of FIG.
In this linear motor, the stator 2 is configured by alternately arranging ring-shaped phase coils 4 and ring-shaped permanent magnet portions 6, and the stator core 5 shown in the first and second embodiments is configured as follows. No.
Other configurations are the same as those of the linear motor of the first embodiment.

  In the stator 2 of this embodiment, since there is no stator core 5, the number of parts is further reduced as compared with that of the embodiment 2, the assembly cost is reduced, and the portion where the stator core 5 is deleted In addition, by occupying the phase coil 4, the cross-sectional area of the phase coil 4 can be greatly increased.

Embodiment 4 FIG.
FIG. 15 is a side sectional view showing a linear motor according to Embodiment 4 of the present invention.
In this linear motor, the stator core 5 is composed of only the core back portion.
On both sides of the phase coil 4 in the axial direction, permanent magnet portions 6 magnetized in the axial direction so as to have different polarities are arranged, and on the outer side in the radial direction of the phase coil 4, it is magnetized in the radial direction. A stator core 5 made of permanent magnets is arranged. In addition, the magnetization directions of the permanent magnet portion 6 and the stator core 5 surrounding the three surfaces of the phase coil 4 are all concentrated with respect to each phase coil 4 or in the axial direction so as to be in the opposite direction (diffusion). Are arranged alternately.
Other configurations are the same as those of the linear motor of the first embodiment.

In the linear motor according to the third embodiment, since there is no stator core 5, the permeance of the permanent magnet portion 6 is reduced and the thrust characteristics are reduced as compared with the case where the stator core 5 is arranged.
On the other hand, in this embodiment, the stator core 5 is composed of a core back portion made of a permanent magnet magnetized in the ring-shaped axial direction, and linear using the stator core 5 made of a magnetic material. Compared with the motor, the total amount of magnetic flux is increased and the thrust characteristics are improved.

FIG. 16 is a side sectional view showing a modification of the linear motor according to the fourth embodiment.
In this modification, the stator core 5 composed only of the core back portion is a first permanent magnet 12 that is a permanent magnet that is magnetized in the axial direction so as to have different polarities, and a permanent magnet. The second permanent magnet 13 is constituted. The first permanent magnet element 12 and the second permanent magnet element 13 are magnetized so as to have the same polarity as the adjacent permanent magnet portions 6.

FIG. 17 is a side sectional view showing another modification of the linear motor according to the fourth embodiment.
In this modification, the stator core 5 constituted only by the core back portion is constituted by permanent magnets magnetized in the axial direction so as to have different polarities. Inside the stator core 5, permanent magnet portions 6 and phase coils 4 having the same outer diameter are alternately arranged. The stator core 5 and the permanent magnet portion 6 disposed inside thereof are magnetized to the same polarity.

Embodiment 5 FIG.
FIG. 18 is a side sectional view of a linear motor according to Embodiment 5 of the present invention.
In this linear motor, the permanent magnet portion 6 magnetized in the axial direction is in contact with the inner peripheral wall surface of the stator core 5, and the permanent magnet portion 6 is in contact with the inner peripheral wall surface of the frame 1 as shown in FIG. The contact object of the permanent magnet unit 6 is different from that of the fourth embodiment.
Further, the frame 1 is made of a magnetic material, which is different from that of FIG. 15 in which the frame 1 is made of a non-magnetic material.

In this embodiment, similarly to the linear motor shown in FIG. 15, the phase coil 4 is magnetized in the radial direction and the magnetic flux of the stator core 5 composed only of the core back portion and in the axial direction. The magnetized permanent magnet portions 6 are alternately arranged along the axial direction so that the magnetization directions are all concentrated or all the opposite directions (diffusion).
In such a linear motor, the magnetic flux line coming out of the outer peripheral portion of the stator core 5 becomes a magnetic circuit that returns to the adjacent stator core 5.
In the linear motors according to the first to fourth embodiments, the frame 1 is made of a non-magnetic material, and the magnetic flux lines that have passed through the frame 1 and have come out of the outer peripheral portion pass through the frame 1 again and are adjacent to the stator. The magnetic circuit returns to the core 5.
On the other hand, in this embodiment, the frame 1 is made of a magnetic material, and the leakage of magnetic flux from the outer periphery of the frame 1 to the outside is reduced, while the permeance of the magnetic circuit is improved and the thrust characteristic is raised. Is possible.

FIG. 19 is a side sectional view showing a modification of the linear motor according to the fifth embodiment.
In this modification, the permanent magnet portion 6 magnetized in the axial direction shown in FIG. 18 is removed, and a fixed magnet composed of a permanent magnet magnetized in each radial direction is formed. The phase coil 4 is arranged on the inner side corresponding to the child core 5, and in this example, the same effect as that of FIG. 18 can be obtained.

Embodiment 6 FIG.
FIG. 20 is a side sectional view showing a linear motor according to the sixth embodiment of the present invention.
In this embodiment, the mover 3 is provided on a shaft 9, a plurality of salient poles 10 fixed to the shaft 9 at a predetermined interval, between adjacent salient poles 10, and at both ends of the shaft 9. The outer diameter dimension is the same in the entire region in the axial direction.
The configuration relating to the stator 2 is the same as that of the linear motor shown in FIG.

In the first to fifth embodiments, the outer diameter of the salient pole 10 is larger than the outer diameter of the shaft 9, and in order to ensure the stroke length S in the axial direction of the shaft 9 (see FIG. 1), the overall length of the frame 1 is , “The length of the stator 2 in the axial direction” + “2S” or more.
On the other hand, in this embodiment, the mover 3 is provided with a non-magnetic material 14 between the salient poles 10 and has the same outer diameter dimension in the entire area in the axial direction. It suffices if the length of the child 2 is the same, and the length of the frame 1 in the axial direction can be made shorter than those of the first to fifth embodiments.

FIG. 21 is a side sectional view showing a modification of the linear motor of FIG.
In this example, the mover 3 in FIG. 20 is covered with a nonmagnetic tube 15.
By using this nonmagnetic tube 15, the nonmagnetic tube 15 slides smoothly with respect to the bearing 11, the mover 3 can move smoothly and the bearing 11 also has a long life.

Embodiment 7 FIG.
FIG. 22 is a side sectional view showing a linear motor according to Embodiment 7 of the present invention, and FIG. 23 is a perspective view showing the mover 3 of FIG.
In this embodiment, a plurality of concave portions are formed in a shaft 9 made of a magnetic material, and a resin is melted and solidified in the concave portions to form the nonmagnetic material 14. A salient pole 10 is formed between the non-magnetic bodies 14. Examples of the method for dissolving the resin include a laser and a beam.
The nonmagnetic material may be made of aluminum, stainless steel or the like in addition to the resin.
Other configurations are the same as those of the linear motor of the sixth embodiment.

  In this embodiment, the same effect as that of the linear motor shown in FIG. 20 can be obtained, and in the mover 3, a part of the shaft 9 also serves as the salient pole 10, and the number of parts can be reduced. it can.

In each of the above-described embodiments, the case has been described in which the mover 3 that is a field element moves linearly with respect to the stator 2 that is an armature. The present invention can be applied even to a linear motor.
In each of the above embodiments, the total number of salient poles 10 is 5 and the total number of phase coils 4 opposed to the salient poles 10 is 6. However, the salient poles 10 are assumed to be an integer of 2 or more. It is possible to increase the thrust accordingly by setting the number of phase coils 5n and the number of phase coils 4 to 6n.
In each of the above embodiments, the shaft 9 is made of a magnetic material. However, the present invention can be applied to a non-magnetic material.
In addition, for the mover 3 of the linear motor according to the seventh embodiment, the entire circumference of the mover 3 may be covered with the nonmagnetic tube 15 shown in FIG.

  1 frame, 2 stator (armature), 3 mover (field element), 4 phase coil, 5 stator core (armature core), 6 permanent magnet part, 7 core back part, 8 teeth part, 9 shaft DESCRIPTION OF SYMBOLS 10 Salient pole, 11 Bearing, 12 1st permanent magnet child, 13 2nd permanent magnet child, 14 Nonmagnetic material, 15 Nonmagnetic tube.

Claims (13)

A cylindrical armature;
A field element provided on the central axis of the armature so as to reciprocate along the central axis relative to the armature by interaction with the armature;
The armature has a plurality of ring-shaped phase coils arranged at intervals along the axial direction, and a permanent magnet portion made of a ring-shaped permanent magnet provided between the phase coils,
The field element has a shaft, and a ring-shaped salient pole made of a magnetic material arranged in a plurality at intervals along the axis of the shaft,
The salient pole has a total number of 5n when n is an integer equal to or greater than 1, and the phase coil facing the salient pole has a total number of 6n.
The three-phase coils are arranged at least once in the order of U + phase, U− phase, V + phase, V− phase, W + phase, and W− phase along the axial direction .
A cylindrical linear motor characterized in that the adjacent permanent magnet portions are magnetized in the axial direction so as to have different polarities . A cylindrical armature;
A field element provided on the central axis of the armature so as to reciprocate along the central axis relative to the armature by interaction with the armature;
The armature has a plurality of ring-shaped phase coils arranged at intervals along the axial direction, and a permanent magnet portion made of a ring-shaped permanent magnet provided between the phase coils,
The field element has a shaft, and a ring-shaped salient pole made of a magnetic material arranged in a plurality at intervals along the axis of the shaft,
The salient pole has a total number of 5n when n is an integer equal to or greater than 1, and the phase coil facing the salient pole has a total number of 6n.
The three-phase coils are arranged at least once in the order of U + phase, V + phase, W + phase, U + phase, V + phase, and W + phase along the axial direction .
A cylindrical linear motor characterized in that the adjacent permanent magnet portions are magnetized in the axial direction so as to have different polarities . The cylindrical linear motor according to claim 1, wherein the permanent magnet portions are arranged at both ends in the axial direction. The cylindrical linear motor according to any one of claims 1 to 3, wherein an armature core made of a magnetic material is provided between the permanent magnet portions. The armature core is composed of at least one of a pair of teeth portions in surface contact with the permanent magnet portion and a core back portion connecting ends of the teeth portions on the opposite side of the salient poles. The cylindrical linear motor according to claim 4 , characterized in that: The cylinder according to claim 5 , wherein the armature core is configured by the teeth portion and the core back portion, and the teeth portion and the core back portion are configured by being divided. Type linear motor. It further comprises a cylindrical frame made of magnetic material,
The cylindrical linear motor according to claim 1, wherein the armature is fixed to an inner periphery of the frame. A cylindrical armature;
A field element provided on the central axis of the armature so as to reciprocate along the central axis relative to the armature by interaction with the armature;
The armature includes a plurality of ring-shaped phase coils arranged at intervals along the axial direction; A permanent magnet portion made of a ring-shaped permanent magnet provided between the phase coils,
The field element has a shaft, and a ring-shaped salient pole made of a magnetic material arranged in a plurality at intervals along the axis of the shaft,
The salient pole has a total number of 5n when n is an integer equal to or greater than 1, and the phase coil facing the salient pole has a total number of 6n.
The three-phase coils are arranged at least once in the order of U + phase, U− phase, V + phase, V− phase, W + phase, and W− phase along the axial direction.
  Between each permanent magnet part, an armature core made of a magnetic material is provided,
  The armature core is composed only of a core back portion made of a permanent magnet, and the adjacent armature cores are magnetized so that the magnetization directions are different from each other. Type linear motor. A cylindrical armature;
  A field element provided on the central axis of the armature so as to reciprocate along the central axis relative to the armature by interaction with the armature;
  The armature has a plurality of ring-shaped phase coils arranged at intervals along the axial direction, and a permanent magnet portion made of a ring-shaped permanent magnet provided between the phase coils,
  The field element has a shaft, and a ring-shaped salient pole made of a magnetic material arranged in a plurality at intervals along the axis of the shaft,
  The salient pole has a total number of 5n when n is an integer equal to or greater than 1, and the phase coil facing the salient pole has a total number of 6n.
  The three-phase coils are arranged at least once in the order of U + phase, V + phase, W + phase, U + phase, V + phase, and W + phase along the axial direction.
  Between each permanent magnet part, an armature core made of a magnetic material is provided,
  The armature core is composed only of a core back portion made of a permanent magnet, and the adjacent armature cores are magnetized so that the magnetization directions are different from each other. Type linear motor. The cylindrical linear device according to any one of claims 1 to 9 , wherein the field element is provided with a nonmagnetic material between the salient poles and has the same outer diameter in the entire axial direction. motor. The field element is composed of a magnetic body, and is composed of a shaft in which a plurality of ring-shaped recesses are formed at intervals along the axial direction, and the non-magnetic body made of resin disposed in the recesses. The cylindrical linear motor according to claim 10 , wherein the shaft and the salient pole between the recesses are integrated. The cylindrical linear motor according to claim 10 or 11 , wherein the field element is entirely covered with a nonmagnetic tube. The armature is a stator, a cylindrical linear motor according to any one of claim 1 to 12, wherein the field element is a movable element.

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