JP4491759B2 - Permanent magnet type linear motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear motor having a permanent magnet as a magnetic field, and in particular, a permanent magnet type linear motor having a field structure in which the armature is the same and the thrust characteristics are changed by changing the magnetic load within a single-axis stroke. About.
[0002]
[Prior art]
A linear motor is characterized in that a linear thrust can be obtained directly by moving a mover against a stator having magnets or coils arranged on a track. It is used as a driving means.
By the way, when the linear motor is used as a driving means for a machine tool or the like, the moving means on the same axis often includes a section where a large thrust is required and a section where it is not. However, in a normal linear motor, magnets or coils of the same size that uniformly generate the same magnetic force are arranged on the same axis, so it cannot be said that the structure is suitable for such needs.
From this point of view, Japanese Patent Application Laid-Open No. 8-331832 discloses, as a linear motor structure capable of switching thrust on the same axis, a stator having a fixed magnet or a coil constituting a fixed side portion of the linear motor, and A magnetic field which is arranged via a stator and a magnetic gap (gap) and which is guided by a guide mechanism and which forms a moving side portion movable on one axis, does not move on the axis. Disclosed is a generation capacity that is determined for each of a plurality of sections provided along the same axis, and the thrust is switched according to the movement position of the movable side portion on the one axis. ing. Specifically, a permanent magnet fixed on a magnet plate at an equal pitch is shortened from a specified position and the width of the permanent magnet is shortened. Under the same drive power source capacity, the thrust constant (number of flux linkages), that is, thrust It is a field structure of a linear motor that lowers and increases the maximum speed.
[0003]
[Problems to be solved by the invention]
However, in the prior art, first, two types of magnet shapes are required, leading to an increase in the cost of the permanent magnets, and at the joints (thrust switching points) of the two types of permanent magnets due to a sudden change in magnetic loading, Cogging thrust will be generated.
Also, when the gap surface of the armature is single and the field and armature are opposed to each other as in the conventional case, the bending in the mechanical system is large due to the magnetic attractive force, limiting the maximum speed of the linear motor, and sliding There was a problem of deteriorating the performance of the linear motor, such as shortening the life of the part.
Therefore, an object of the present invention is to provide a high-performance linear motor that can suppress the generation of cogging thrust, has a low manufacturing cost, and is high in performance.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the permanent magnet linear motor of the present invention uses a magnet plate in which a plurality of field permanent magnets are arranged in a straight line as a stator, and the permanent magnet along the longitudinal direction of the magnet plate. The armature, which is arranged opposite to the row and the magnetic gap and is wound with an armature coil, is configured as a mover, and the magnet plate has all permanent magnets arranged and fixed at the same pitch on the surface of the magnetic flat plate. The first magnet plate and the second magnet plate in which ferromagnetic blocks and permanent magnets are alternately arranged and fixed at equal pitches on the surface of the magnet flat plate, A magnet plate and the second magnet plate are combined in the longitudinal direction. As a type of this permanent magnet type linear motor, a permanent magnet array is formed on a horizontal plane, and an armature is opposed to the permanent magnet array via a magnetic air gap, or both sides of the armature are magnetized. A configuration in which permanent magnet arrays are arranged via a static air gap can be applied.
[0005]
Further, there are the following embodiments.
(1) The gap magnetic field can be balanced by making the shape and size of the ferromagnetic block the same as that of the permanent magnets arranged alternately.
(2) By changing the shape and size of the permanent magnet of the second magnet plate to be the same as the shape and size of the permanent magnet of the first magnet plate, and further making the shape and size of the ferromagnetic block the same, the magnet switching portion Can be minimized.
(3) The number N _m of magnets to be arranged and fixed in the second magnet plate in which ferromagnetic blocks and permanent magnets are alternately arranged is N _m = 2 · n (n is a natural number)
By doing so, the gap magnetic field in the second magnet plate can be made uniform.
(4) By using a sintered material obtained by baking and solidifying iron powder as the material of the ferromagnetic block of the second magnet plate, the cost of the magnet can be reduced.
(5) When the stroke direction dimension W _b of the ferromagnetic block arranged and fixed on the second magnet plate and the dimension W _{m of the} permanent magnet are the magnetic pole pitch λ _p , W _b = W _m = 3 / 4λ _p By setting it to ˜6 / 7λ _p , third-order, fifth-order, and seventh-order harmonic components included in the gap magnetic field distribution can be reduced, and thrust ripple with respect to the position in the stroke direction due to this harmonic can be reduced.
(6) Protection can be performed by resin molding so as to cover all of the permanent magnet and the ferromagnetic block on the magnet plate.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of a permanent magnet type linear motor showing a first embodiment of the present invention. 2 is a front view of FIG. 1 viewed from the direction of arrow A. FIG. In this example, a description will be given by using an example of a gap-facing linear motor in which a linear motor magnet plate is disposed facing only one side of an armature portion of a linear motor.
In the figure, 1 is a base, 2 is a permanent magnet, 3 is a first magnet plate, 4a and 4b are second magnet plates, 5 is a ferromagnetic block made of a magnetic material, 6 is a guide rail, and 7 is a slider. , 8 is a table, 9 is an armature, 9A is an armature core, 9B is an armature coil, 10 is a feeder, and 11 is a cable bear.
A first magnet plate 3 having all permanent magnets 2 arranged and fixed at an equal pitch is fixed to the upper surface of the base 1, and second magnet plates 4a and 4b are linearly arranged on both sides thereof. At this time, the joint between the first magnet plate 3 and the second magnet plates 4a and 4b is arranged such that the permanent magnet 2 and the ferromagnetic block 5 are adjacent to each other. The second magnet plates 4a and 4b are configured by reversing the polarity of the permanent magnet 2 and are alternately arranged to have the same polarity. Linear guides composed of guide rails 6 and sliders 7 are fixed in parallel on both sides of the first and second magnet plates 3, 4 a and 4 b.
The movable body portion is fixed to the table 8 with an armature 9 in which an armature coil 9B is wound around an armature core 9A opposed to the field portion via a gap. It is supported dynamically. The power supply line (lead wire) 10 of the armature 9 passes through the cable bear 11 for movement processing during linear movement.
[0007]
FIG. 3 schematically shows the joint between the first magnet plate 3 and the second magnet plate 4a and the magnetic field distribution thereof, and also shows the relationship between the magnet shape and the magnet pitch. The dimension Wb in the stroke direction of the ferromagnetic block 5 and the dimension Wm in the stroke direction of the permanent magnet 2 are determined in the range of 3/4 to 5/6 of the magnetic pole pitch λp. The example in the figure is for 4 / 5λp. Thus, by determining the dimensions of the permanent magnet 2 and the ferromagnetic block 5 in the stroke direction, the third-order, fifth-order, and seventh-order harmonic components included in the gap magnetic field distribution can be reduced. The thrust ripple with respect to the position of can be reduced.
In this embodiment, the armature 9 supported so as to be linearly movable by the linear guide is opposed to the field part through the gap, and the armature is energized so that a relative linear motion is generated between the field part and the armature. Direct motion operation is performed by generating
As described above, in this embodiment, the first magnet plate 3 in which permanent magnets are all arranged and fixed at the same pitch on the surface of the magnetic flat plate is used in the high thrust and low speed movement region. In the second magnet plates 4a and 4b used for the stroke range that requires a region, the ferromagnetic blocks 5 and the permanent magnets 2 are alternately arranged and fixed at an equal pitch so that there is no sudden change in magnetic loading. It is a thing.
Further, by using an iron powder sintered material as the material of the ferromagnetic block 5, the manufacturing cost can be reduced to about 1/10 of the cost of rare earth magnets of the same size, and the magnetic loading can be suppressed to about -20%. It is done.
[0008]
Next, a second embodiment of the present invention will be described.
FIG. 4 is a plan view of a permanent magnet type linear motor showing a second embodiment of the present invention, and FIG. 5 is a front view of FIG.
The second embodiment is different from the first embodiment in that field side magnet plates are arranged on both sides of the armature portion of the linear motor (magnetic flux penetrating structure).
First magnet plates 3 and 3 having all permanent magnets 2 arranged and fixed at an equal pitch are fixed on the upper surface of the base 1, and second magnet plates 4a and 4b are arranged on both sides in the longitudinal direction. Let The second magnet plate 4a is composed of a ferromagnetic block 5 and an N-pole permanent magnet 2, and the second magnet plate 4b is composed of a ferromagnetic block 5 and an S-pole permanent magnet 2. Yes, and the second magnet plates 4a and 4b are a pair. The joints between the first magnet plates 4a and 4b and the second magnet plate 3 are arranged so that the permanent magnet 2 and the ferromagnetic block 5 are adjacent to each other, and the field magnetic flux penetrates through the armature. It has a magnetic circuit structure. Linear guides composed of guide rails 6 and sliders 7 are fixed in parallel on both sides of the magnet plate.
Further, the armature 9 is fixed to the table 8 on the table 8 so as to face the field portion through a gap, and is supported by the linear guide. The power supply line (lead wire) 10 of the armature 9 passes through the cable bear 11 for movement processing during linear movement.
FIG. 6 schematically shows the joint between the first magnet plate 3 and the second magnet plates 4a and 4b and the magnetic field distribution, and also shows the relationship between the magnet shape and the magnet pitch. . The dimension Wb in the stroke direction of the ferromagnetic block 5 and the dimension Wm in the stroke direction of the permanent magnet 2 are determined in the range of 3/4 to 5/6 of the magnetic pole pitch λp. The example in the figure is for 4 / 5λp.
The second embodiment described above also has the same operation as the first embodiment.
[0009]
【The invention's effect】
As described above, according to the present invention, in the high-thrust, low-speed movement region, the first magnet plate in which permanent magnets are all arranged and fixed at the same pitch on the surface of the magnetic flat plate is used. The second magnet plate used in the stroke range that requires the high-speed movement area is mechanically deformed so that there is no sudden change in magnetic loading by fixing the ferromagnetic block 5 and the permanent magnet 2 alternately at equal pitches. The magnetic attraction force that causes the problem is canceled, and smooth movement with reduced cogging becomes possible.
Further, by using an iron powder sintered material as the material of the ferromagnetic block, the manufacturing cost can be reduced to about 1/10 of the cost of the rare-earth magnet of the same dimension, and the magnetic loading can be suppressed to about −20%. . Incidentally, in the conventional structure, in order to achieve the same cost, the width of the magnet has to be halved. In this case, the magnetic loading is reduced to -50%, the efficiency is reduced, and heat is generated. Will increase.
Further, by setting the stroke size of the permanent magnet and the ferromagnetic block within the range of 3/4 to 5/6 of the magnetic pole pitch λp, the third, fifth and seventh harmonic components included in the gap magnetic field distribution are reduced. It is possible to reduce the thrust ripple with respect to the position in the stroke direction due to the higher harmonics, and thus the speed ripple, which is an important characteristic of the linear motor, can be suppressed to a low level, and a high-performance linear motor can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view of a permanent magnet type linear motor showing a first embodiment of the present invention.
FIG. 2 is a front view of FIG. 1 viewed from the direction of arrow A. FIG.
FIG. 3 is a diagram schematically showing a joint portion between a first magnet plate and a second magnet plate and a magnetic field distribution thereof according to the first embodiment of the present invention.
FIG. 4 is a plan view of a permanent magnet type linear motor showing a second embodiment of the present invention.
5 is a front view of FIG. 4 viewed from the direction of arrow A. FIG.
FIG. 6 is a diagram schematically showing a joint portion between a first magnet plate and a second magnet plate and a magnetic field distribution thereof according to a second embodiment of the present invention.
[Explanation of symbols]
1: base, 2: permanent magnet, 3: first magnet plate, 4, 4a, 4b: second magnet plate, 5: ferromagnetic block, 6: rail, 7: guide, 8: table, 9: Armature, 9A: Armature core, 9B: Armature coil, 10: Feed line, 11: Cable bear

Claims (9)

A magnet plate in which a plurality of field permanent magnets are arranged in a straight line is used as a stator, and the permanent magnet array is disposed opposite to the permanent magnet array along a magnetic gap along the longitudinal direction of the magnet plate. A wound armature is configured as a mover,
The magnet plate includes a first magnet plate in which permanent magnets are arranged and fixed on the surface of the magnetic flat plate at an equal pitch, and a ferromagnetic block and permanent magnets alternately on the surface of the magnetic flat plate at an equal pitch. It is composed of a fixed second magnet plate,
A permanent magnet type linear motor, wherein the first magnet plate and the second magnet plate are coupled in the longitudinal direction.   2. The permanent magnet linear motor according to claim 1, wherein the permanent magnet array is formed on a horizontal plane, and the armature is opposed to the permanent magnet array via a magnetic gap.   The permanent magnet linear motor according to claim 1, wherein the permanent magnet rows are arranged on both sides of the armature via a magnetic gap.   The permanent magnet type linear motor according to any one of claims 1 to 3, wherein the ferromagnetic block has the same shape and shape as the permanent magnets arranged alternately. 5. The shape of the permanent magnet of the second magnet plate is the same as the shape of the permanent magnet of the first magnet plate, and the shape of the ferromagnetic block is made the same. A permanent magnet type linear motor according to any one of the above items. The number N _m of magnets arranged and fixed in the second magnet plate in which the ferromagnetic block and the permanent magnet are alternately arranged is N _m = 2 · n (n is a natural number).
The permanent magnet linear motor according to any one of claims 1 to 5, wherein   7. The permanent magnet linear motor according to claim 1, wherein a sintered material obtained by baking and solidifying iron powder is used as a material for the ferromagnetic block of the second magnet plate. The size W _m of the stroke dimension W _b and the permanent magnets arranged fixed ferromagnetic blocks in the second magnet plate, if the magnetic pole pitch is _{λ p, W b = W m} = 3 / 4λ p ~6 permanent magnet type linear motor according to any one of claims 1 7, / 7λ _p and the possible features.   9. The permanent magnet linear motor according to claim 1, wherein the permanent magnet linear motor is resin-molded so as to cover all of the permanent magnet and the ferromagnetic block on the magnet plate.

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