JP2017189017A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor capable of suppressing an iron loss.SOLUTION: A linear motor according to one embodiment includes: a stator; a movable element; a base yoke portion; a magnet; a coil; and an opposite portion. The stator and the movable element face each other. The base yoke portion is possessed by a first member of one of the stator and the movable element, and is disposed apart from the other second member. The magnet is possessed by one of the first member and the second member. The coil is possessed by the other of the first member and the second member. The opposite portion is disposed at a second member side of the base yoke section, and supports the magnet or the coil attached to the first member by an opposite surface to the second member. The opposite portion comprises a plurality of magnetic steel sheets.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a linear motor.

  Conventionally, there is a linear motor called a voice coil motor as a motor used in a compressor for a cryogenic refrigerator. In the conventional linear motor, the coil is mounted on the mover and moves. For this reason, it took time and effort to route the wiring connected to the coil. Further, in the movable coil, the wiring was easily fatigued. On the other hand, there is a linear motor in which a magnet is mounted on a mover and moves. However, in the linear motor in which the magnet moves, the magnetic flux acting on the stator is changed to easily generate eddy current, and the iron loss of the stator tends to increase.

JP 2000-205680 A

  The problem to be solved by the present invention is to provide a linear motor capable of suppressing iron loss.

  The linear motor of the embodiment includes a stator and a mover, a base yoke portion, a magnet, a coil, and a facing portion. The stator and the mover face each other. The base yoke portion has one first member of the stator and the mover, and is disposed away from the other second member. One of the first member and the second member has the magnet. The coil has the other of the first member and the second member. The facing portion is disposed on the second member side of the base yoke portion, and supports a magnet or a coil attached to the first member on a surface facing the second member. The facing portion includes a plurality of electromagnetic steel plates.

The sectional side view of the linear motor of 1st Embodiment. II-II sectional view taken on the line of FIG. The perspective view of an opposing part. The sectional side view of the linear motor of 2nd Embodiment. VV sectional view taken on the line of FIG. The side view of the linear motor of 2nd Embodiment.

  Hereinafter, a linear motor according to an embodiment will be described with reference to the drawings. In addition, about the member which is common in each embodiment, a common number is attached | subjected and the description may be abbreviate | omitted.

(First embodiment)
FIG. 1 is a side sectional view of the linear motor according to the first embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG. 1 corresponds to a cross-sectional view taken along line II in FIG. The linear motor 10 is used for a compressor for a cryogenic refrigerator, for example. In this specification, the axial direction, radial direction, and circumferential direction of the linear motor are simply referred to as axial direction, radial direction, and circumferential direction, respectively.
As shown in FIG. 1, the linear motor 10 according to the first embodiment includes a stator (first member, outer member) 20 and a mover (second member) 30. The stator 20 and the mover 30 face each other. Further, the mover 30 is disposed inside the stator 20.
The stator 20 includes an outer yoke (base yoke portion) 21, an inner yoke (opposing portion) 22, a first coil (coil) 23, and a second coil (coil) 24. The mover 30 includes a movable yoke 31, a first permanent magnet (magnet) 32, and a second permanent magnet (magnet) 33. The linear motor 10 is a so-called MM type motor in which a magnet (a first permanent magnet 32 and a second permanent magnet 33) is provided on the mover 30.

The outer yoke 21 has a cylindrical shape. In particular, a cross section cut in a direction perpendicular to the axial direction has a circular cylindrical shape as shown in FIG. The outer yoke 21 is made of steel. However, it may be formed of stainless steel other than steel or other magnetic material. The outer yoke 21 is disposed away from the mover 30.
The inner yoke 22 is disposed along an inner peripheral surface that is a surface of the outer yoke 21 on the movable element 30 side. The inner yoke 22 has a cylindrical shape. The inner yoke 22 supports the first coil 23 and the second coil 24 on the surface facing the mover 30.
As shown in FIG. 3, the inner yoke 22 includes a plurality of disk-like (hollow plate-like ring) ring members 25, 25. The plurality of ring members 25, 25... Are arranged in parallel in the moving direction of the mover 30. The moving direction of the mover 30 is the axial direction. The side surfaces of the adjacent ring members 25 are in contact with each other. The inner yoke 22 is formed in a cylindrical shape by a plurality of ring members 25. The outer yoke 21 and the inner yoke 22 may be integrated.

The ring member 25 is made of, for example, a silicon steel plate. A silicon steel plate is an iron plate in which magnetic properties are improved by adding silicon to a ferromagnetic material. Examples of the ferromagnetic material include cobalt, nickel, iron and the like, but iron is used in the silicon steel plate. In silicon steel plates, silicon is added to iron to control the alignment of crystal orientation and the width of magnetic domains.
For example, the surface of the ring member 25 is subjected to an insulation process covered with an insulator. The ring member 25 has an insulator on the surface. The ring member 25 is not easily energized by an insulation process.

  Both the first coil 23 and the second coil 24 are supported on the inner surface of the inner yoke 22. Both the first coil 23 and the second coil 24 are wound around the rotating shaft 80 of the outer yoke 21. The first coil 23 and the second coil 24 are spaced apart from each other in the axial direction of the linear motor 10. The winding direction of the first coil 23 is opposite to the winding direction of the second coil 24. The winding direction of the first coil 23 and the winding direction of the second coil 24 may be the same direction. In this case, the direction of the current flowing through the first coil 23 and the second coil 24 may be reversed.

The movable yoke 31 has a cylindrical shape. The movable yoke 31 is disposed coaxially with the outer yoke 21 and the inner yoke 22. The movable yoke 31 has a cylindrical shape in which a hollow portion is formed. By forming the hollow portion, the weight of the mover 30 is reduced while considering the amount of magnetic flux.
The first permanent magnet 32 and the second permanent magnet 33 are attached to the outer peripheral surface of the movable yoke 31. The first permanent magnet 32 and the second permanent magnet 33 are spaced apart from each other in the axial direction of the linear motor 10. The distance between the first permanent magnet 32 and the second permanent magnet 33 is substantially the same as the distance between the first coil 23 and the second coil 24. Further, the separation distance between the first coil 23 and the second coil 24 may be a distance other than the same depending on factors such as the effective stroke, the moving range, and the thrust of the linear motor 1.
Both the first permanent magnet 32 and the second permanent magnet 33 have a ring shape. Moreover, the 1st permanent magnet 32 and the 2nd permanent magnet 33 may be divided into the ring shape, and the division | segmentation part made into the fan shape may be located in a ring shape.

The north pole of the first permanent magnet 32 is disposed on the radially inner side of the outer yoke 21, and the south pole is disposed on the outside. The magnetization direction of the first permanent magnet 32 is the radial direction. The N pole of the second permanent magnet 33 is arranged on the outer side in the radial direction of the outer yoke 21, and the S pole is arranged on the inner side in the radial direction. The magnetization direction of the second permanent magnet 33 is the radial direction. In the first permanent magnet 32 and the second permanent magnet 33, the S pole and the N pole are arranged in the radial direction of the outer yoke 21 so as to be reversed inside and outside. Further, the N pole of the first permanent magnet 32 is arranged on the radially outer side and the S pole of the outer yoke 21, the N pole of the second permanent magnet 33 is arranged on the radially inner side of the outer yoke 21, and the S pole is arranged on the outer side. May be.
As described above, the magnetic poles of the first permanent magnet 32 and the magnetic poles of the second permanent magnet 33 are arranged in a contradictory manner. Moreover, the 1st permanent magnet 32, the 2nd permanent magnet 33, the outer yoke 21, and the needle | mover 30 are arrange | positioned so that a magnetic circuit may be obstruct | occluded.

In the linear motor 10, when a current is passed through the first coil 23 and the second coil 24, Lorentz force is generated between the first coil 23 and the first permanent magnet 32. Similarly, Lorentz force is also generated between the second coil 24 and the second permanent magnet 33. These Lorentz forces act in the axial direction of the linear motor 10. The current passed through the first coil 23 and the second coil 24 may be an alternating current such as a sine wave current or a rectangular wave current. Further, the current flowing through the first coil 23 and the second coil 24 may be a direct current.
The first permanent magnet 32 and the second permanent magnet 33 generate a magnetic flux 90. The first permanent magnet 32 generates a magnetic flux 90 outward in the radial direction. The second permanent magnet 33 generates a magnetic flux 90 toward the radially inner side. The magnetic flux 90 circulates mainly through the first permanent magnet 32, the first coil 23, the inner yoke 22, the outer yoke 21, the inner yoke 22, the second coil 24, the second permanent magnet 33, and the movable yoke 31 in this order. To do.

At this time, the Lorentz force generated between the first coil 23 and the first permanent magnet 32 works in the same direction as the Lorentz force generated between the second coil 24 and the second permanent magnet 33. The mover 30 moves in the axial direction by this Lorentz force. The moving range of the first permanent magnet 32 and the second permanent magnet 33 in the mover 30 is shorter than the length of the outer yoke 21 in the moving direction of the mover 30.
The inner yoke 22 is formed by arranging a plurality of ring members 25 formed of silicon steel plates in parallel. The magnetic flux 90 flows mainly in the radial direction through the inner yoke 22 and reaches the outer yoke 21. The outer yoke 21 has a cylindrical shape, and the magnetic flux 90 flows mainly through the outer yoke 21 in the axial direction.

A case where the direction of the current supplied to the first coil 23 and the second coil 24 is reversed will be considered. In this case, the Lorentz force between the first coil 23 and the second coil 24 and the first permanent magnet 32 and the second permanent magnet 33 also acts in the axial direction. Further, when the direction of the current supplied to the first coil 23 and the second coil 24 is reversed, the direction in which the Lorentz force acts is reversed to the opposite side of the axial direction.
The mover 30 reciprocates by reversing the direction of the current supplied to the first coil 23 and the second coil 24. Although the range of the reciprocating motion of the mover 30 can be determined as appropriate, it is within a range slightly shorter than the width (length in the axial direction) of the outer yoke 21, for example. The range of the reciprocating motion of the mover 30 may be within the range of the width of the outer yoke 21 or may be the range beyond the range of the width of the outer yoke 21.

In the linear motor 10 described above, the stator 20 is provided with an inner yoke 22 in which a plurality of ring members 25 made of silicon steel plates are arranged in parallel.
Assume that the inner yoke 22 is not provided on the stator 20 of the linear motor 10. At this time, an eddy current may be generated between the first coil 23 and the outer yoke 21 through which the magnetic flux 90 passes and between the outer yoke 21 and the second coil 24. This eddy current may be generated by a change in the magnetic flux flowing in the outer yoke 21 in the radial direction. This eddy current may cause eddy current loss and increase iron loss.
In this regard, in the linear motor 10, the inner yoke 22 is provided between the first coil 23 and the outer yoke 21 and between the outer yoke 21 and the second coil 24. The inner yoke 22 is formed by arranging a plurality of ring members 25 made of silicon steel plates. For this reason, it is considered that the eddy current generated in the inner yoke 22 can be completed by an eddy current having a diameter approximately equal to the thickness of the ring member 25. Therefore, eddy current loss can be reduced.
Similarly, the generation of eddy currents can be suppressed between the inner yoke 22 and the second coil 24. Therefore, eddy current loss can be reduced. Therefore, iron loss in the linear motor 10 can be suppressed.

In addition to the inner yoke 22, the linear motor 10 is provided with an outer yoke 21. For this reason, since the inner yoke 22 can be reinforced by the outer yoke 21, the rigidity of the linear motor 10 can be increased. Furthermore, since the outer yoke 21 is steel, the rigidity of the linear motor 10 can be further increased.
Moreover, since a magnet is arrange | positioned at the outer periphery of the needle | mover 30, a big magnetic flux acts on the inner peripheral side of the stator 20 near a magnet. Therefore, a large eddy current is generated on the inner peripheral side of the stator 20 as compared with the outer peripheral side of the stator 20 far from the magnet. On the other hand, in this embodiment, since the inner yoke 22 formed of a silicon steel plate is disposed on the inner peripheral side of the stator 20, eddy current loss can be effectively suppressed.

  The linear motor 10 has a cylindrical shape. For this reason, gas etc. can be easily enclosed with the linear motor 10 by obstruct | occluding the both ends of an axial direction. Therefore, the linear motor 10 can be suitably used as a compressor for a cryogenic refrigerator. The linear motor 10 has a cylindrical shape. For this reason, it is possible to easily equalize the pressure in the linear motor 10. Therefore, the linear motor 10 can be more suitably used as a compressor for a cryogenic refrigerator.

In the linear motor 10, the moving range of the first permanent magnet 32 and the second permanent magnet 33 in the mover 30 is shorter than the length of the outer yoke 21 in the moving direction of the mover 30. Thereby, even when the needle | mover 30 moves to the edge part vicinity of the outer yoke 21, the reduction | decrease of the magnetic flux amount which acts on the stator 20 can be suppressed. Cogging of the linear motor 10 can be suppressed by suppressing the decrease in the amount of magnetic flux.
An MM motor in which a magnet is provided on a mover generally has a long life and is excellent in maintenance-free. Furthermore, in the linear motor 10 described above, since cogging can be suppressed, the life extension and the maintenance-free property are further enhanced.

  In the linear motor 10 described above, the outer yoke 21 is provided in addition to the inner yoke 22 in which a plurality of ring members 25 made of silicon steel plates are arranged in parallel in the axial direction. Since the silicon steel plate is a hard and brittle material, it is difficult to process such as tapping the inner yoke 22 for assembly. For this reason, there is a concern about a decrease in assemblability. In this respect, in the linear motor 10 described above, the outer yoke 21 can be easily processed such as tapping. Therefore, it is possible to suppress a decrease in assemblability.

By the way, as a supporting member, it is also conceivable to use a powdered iron core formed in a cylindrical shape. The dust core is an iron core formed by pressing a magnetic material, covering the surface with an insulating film, and mixing with a binder.
However, since the powder iron core is manufactured by sintering, it is the same as the silicon steel plate in that it is difficult to cut taps. Moreover, since a powder iron core is manufactured using a large-sized type | mold, it takes time to manufacture. In this respect, the silicon steel sheet can be manufactured with a simple mold. Moreover, in the linear motor 10 described above, the inner yoke 22 is formed by a plurality of ring members 25 made of a silicon steel plate. For this reason, since the ring member 25 can be made small, the manufacture of the ring member 25 can be simpler.
Thus, since the inner yoke 22 can be manufactured with a simple mold or the like, the linear motor 10 can be easily manufactured as compared with the case where the support member is provided by the dust core.

It is also conceivable to arrange a plurality of plate-like silicon steel plates that are continuous in the axial direction in the circumferential direction along the radial direction. Thus, it is considered that the generation of eddy current can be suppressed even when a plurality of silicon steel plates are provided.
However, when the silicon steel plates are arranged side by side in the circumferential direction as described above, a gap is generated between the silicon steel plates, which may cause a decrease in rigidity. Moreover, since a silicon steel plate is a hard and brittle material, it is difficult to process such as cutting taps, which may cause a decrease in assemblability. In this regard, in the linear motor 10 described above, the outer yoke 21 is provided, and the first coil 23 and the second coil 24 are supported by the inner yoke 22 provided on the inner side surface of the outer yoke 21.
Since the gap can be reduced between the inner yoke 22 and the outer yoke 21, a reduction in rigidity can be suppressed. In addition, since the outer yoke 21 can be processed such as tapping, it is possible to suppress a decrease in assembling property.

(Second Embodiment)
4 is a side sectional view of the linear motor according to the second embodiment, FIG. 5 is a sectional view taken along the line VV in FIG. 6, and FIG. 6 is a side view of the linear motor according to the second embodiment. 4 corresponds to a cross-sectional view taken along line IV-IV in FIG. The linear motor of the second embodiment is different from the first embodiment in that a slit is provided in the outer yoke. Regarding the linear motor of the second embodiment, description of the same parts as those of the first embodiment may be omitted.
As shown in FIG. 4, the linear motor 40 according to the second embodiment includes a stator 50 and a mover 30. The mover 30 has a configuration common to the first embodiment. The stator 50 and the mover 30 face each other. Further, the mover 30 is disposed inside the stator 50.
The stator 50 includes an outer yoke 51, an inner yoke 22, and a first coil 23 and a second coil 24. The inner yoke 22, the first coil 23, and the second coil 24 have the same configuration as that of the first embodiment.

The outer yoke 51 has a cylindrical shape or a cylindrical shape. This point is common to the first embodiment. The outer yoke 51 includes a plurality of slits 52, 52. The plurality of slits 52, 52... Are provided along the axial direction as shown in FIGS.
The plurality of slits 52, 52,... Are spaced apart at substantially equal intervals in the circumferential direction. For this reason, the distance between the adjacent slits 52 and 52 is constant. Further, the slits 52, 52... Are shorter than the length of the outer yoke 51 in the axial direction. For this reason, a part of the outer yoke 51 is left at both ends of the slit 52.

  In the above linear motor 40, the stator 20 is provided with an inner yoke 22 in which a plurality of ring members 25 made of silicon steel plates are arranged in parallel. For this reason, generation of a large eddy current in the inner yoke 22 can be suppressed. Therefore, since eddy current loss can be reduced, iron loss in the linear motor 40 can be suppressed.

In the linear motor 40, the outer yoke 51 is provided with a plurality of slits 52, 52. For this reason, since the eddy current due to the flow of magnetic flux can be further reduced in the outer yoke 51 in addition to the inner yoke 22, further iron loss can be suppressed.
The outer yoke 51 is provided with slits 52, 52, but a part of the outer yoke 51 made of steel is left at both ends in the axial direction. For this reason, the fall of the rigidity of the outer yoke 51 is suppressed. Therefore, it is possible to suitably suppress the iron loss due to the eddy current while ensuring the rigidity of the linear motor 10.

In the linear motor 10 described above, a permanent magnet is provided on the mover, and a coil is provided on the stator. On the other hand, the mover may be provided with a coil, and the stator may be provided with a permanent magnet. In this case, a coil may be provided on the stator side of the movable yoke of the mover, and a permanent magnet may be provided on the mover side of the outer yoke of the stator. Further, the support member is provided on the movable element, and may be provided between the movable yoke and the coil.
Moreover, you may provide the support member formed with the electromagnetic steel plate in a needle | mover. In this case, the support member is disposed on the outer peripheral side of the mover, the movable yoke is disposed on the inner peripheral side of the mover, and the support member is reinforced by the movable yoke. One stator is formed only by the outer yoke. In this case, a coil may be provided on the stator and a permanent magnet may be provided on the mover, or a permanent magnet may be provided on the stator and a coil may be provided on the mover.
In the linear motor 10 described above, the mover 30 is disposed inside the stator 20, but the stator may be disposed inside the mover. In this case, the stator may be provided with a coil, the mover may be provided with a permanent magnet, the stator may be provided with a permanent magnet, and the mover may be provided with a coil.
Further, in the linear motor 10 described above, the stator 20 serving as the outer member is cylindrical, but may be another cylindrical shape. For example, the outer member may have a rectangular tube shape with a polygonal cross section, or may have an elliptic tube shape with an elliptical cross section. Further, the outer member may have a U-shape other than the cylindrical shape.

  Moreover, although the ring member 25 which comprises the inner yoke 22 is formed with the silicon steel plate, you may be formed with electromagnetic steel plates other than a silicon steel plate. Further, the ring member 25 is subjected to an insulation process covered with an insulator, but may not be subjected to an insulation process. Moreover, what is necessary is just to make a ring member into the shape according to the cross-sectional shape of the outer member, when an outer member is cylindrical shapes other than cylindrical shape. For example, in the case where the outer member is a rectangular tube shape, a rectangular hollow plate material may be used.

  According to at least one embodiment described above, iron loss can be suppressed by having a support member including a plurality of electromagnetic steel sheets. Moreover, the rigidity of the linear motor can be ensured by arranging the support member together with the outer yoke.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Linear motor, 20 ... Stator (1st member, outer member), 21 ... Outer yoke (base yoke part), 22 ... Inner yoke (opposing part), 23 ... 1st coil (coil), 24 ... 2nd coil ( Coil), 25 ... ring member (magnetic steel plate), 30 ... mover (second member), 31 ... movable yoke, 32 ... first permanent magnet (magnet), 33 ... second permanent magnet (magnet), 40 ... linear Motor: 50 ... Stator, 51 ... Outer yoke, 52 ... Slit, 80 ... Rotating shaft, 90 ... Magnetic flux

Claims (9)

A stator and a mover facing each other;
A first yoke member of one of the stator and the mover, and a base yoke portion disposed away from the other second member;
One of the first member and the second member has a magnet;
A coil that the other of the first member and the second member has;
An opposing portion that is disposed on the second member side of the base yoke portion and supports a magnet or coil of the first member on a surface facing the second member;
The facing portion includes a plurality of electromagnetic steel plates.
Linear motor. The mover has the magnet,
The stator has the coil;
The linear motor according to claim 1. The outer member disposed outside of the first member and the second member has a cylindrical shape.
The linear motor according to claim 1 or 2. The cylindrical shape is a cylindrical shape,
The linear motor according to claim 3. The plurality of electromagnetic steel plates are juxtaposed in the moving direction of the mover,
The linear motor according to any one of claims 1 to 4. The electromagnetic steel sheet has a hollow plate-like ring shape,
The linear motor according to any one of claims 1 to 4. The electromagnetic steel sheet has an insulator on the surface,
The linear motor as described in any one of Claims 1-6. The mover has the magnet,
The stator has the base yoke portion,
The moving range of the magnet in the mover is shorter than the length of the base yoke part in the moving direction of the mover.
The linear motor as described in any one of Claims 1-7.   The linear motor according to any one of claims 1 to 8, wherein the mover moves by a Lorentz force generated between a current flowing through the coil and a magnetic flux of the magnet.

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