JP2002238241A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor having such a pole structure as the flux density can be increased in the gap between the armature and the inductor and the maximum thrust can be enhanced significantly as compared with prior art. SOLUTION: The linear motor comprises an armature 11 having a plurality of poles 16 arranged at the forward end of the tees 13 of an armature core 12 (the length per pole is referred to pole pitch Pm), and an inductor 2 disposed oppositely to the poles 16 through an air gap while having inductor teeth 3 wherein the armature 11 serves as a mover 10 and the inductor 2 serves as a stator 1. When two permanent magnets 17a and 17b are arranged in one pole pitch, magnetizing direction of one permanent magnet 17a is matched with he advancing direction of the mover and magnetizing direction of the other permanent magnet 17b is shifted by 90 deg. from that of the permanent magnet 17a. A relation 0.3<=Wb/Pm<1.0 is set between the pole pitch Pm and the width Wb of the permanent magnet 17b in the pole pitch direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor requiring high speed and high acceleration / deceleration linear motion in the field of factory automation (FA) such as machine tools and semiconductor manufacturing equipment.

[0002]

2. Description of the Related Art Conventionally, in the field of factory automation (FA) such as machine tools and semiconductor manufacturing equipment, linear motors requiring high-speed and high-acceleration linear motion are required to have a large maximum thrust with respect to the motor size. I have. For example, as such a linear motor, there is one disclosed in Japanese Patent Publication No. 5-34901. FIG. 8 shows a conventional linear motor,
(A) is a side sectional view thereof, (b) is (a)
3 shows an enlarged view of the magnetic pole in FIG. The direction of the arrow (↑ ↓) in the figure indicates the magnetization direction of each permanent magnet. In the figure, 1 is a stator, 2 is an inductor, 3 is an inductor tooth, 10 is a mover, 11 is an armature, 12 is an armature core,
13 is a tooth, 14 is a yoke, 15 is an armature winding, 16
Is a magnetic pole, and 18 is a permanent magnet. The stator 1 is composed of an inductor 2 made of a magnetic material having inductor teeth 3 formed at predetermined intervals λ in the traveling direction. For example, the magnetic material is a laminated electromagnetic steel plate. The armature 10 includes an armature core 12 in which three teeth 13 and a yoke 14 connecting them are integrated, and three teeth 13 concentratedly wound around the three teeth 13.
It is composed of an armature winding 15 of a phase (U, V, W) and an armature 11 composed of a magnetic pole 16 provided at the tip of each tooth 13. For example, a laminated electromagnetic steel sheet is used as the material of the armature core 12. One magnetic pole 16 consisting of 6 poles
The six permanent magnets 18 are arranged such that the pitch Pm is λ / 2 and the adjacent magnets have different polarities. That is, the angle difference θ between the magnetization directions of the adjacent permanent magnets 18 is 180 degrees, and the number n of the permanent magnets used for the magnetic pole per pole is one. Adjacent teeth 13
The interval between the teeth 13 is 4 × λ + λ / 3, which is the sum of the width 3 × λ of the teeth 13 and the width λ + λ / 3 between the teeth 13.
The mover 10 is supported by a linear guide (not shown) or the like so as to be movable in the traveling direction. Next, the operation principle will be described. The magnetic flux of the permanent magnet 18 flows through a magnetic circuit constituted by the teeth 13, the yoke 14, the air gap, and the inductor teeth 3. Since the phase difference between the teeth 13 of each phase is 120 degrees in electrical angle, when the mover 10 is moved, magnetic fluxes having an electrical angle difference of 120 degrees interlink with the armature windings 15 in each phase. A three-phase induced voltage is generated. Conversely, when a three-phase sine wave current is applied to the armature winding 15 of each phase, a thrust is generated as a three-phase synchronous motor, and the mover 10 moves linearly on the stator 1.

[0003]

In the linear motor of the prior art, in the relationship between the current flowing through the armature winding 15 and the thrust, when the current increases, the thrust is not generated in accordance with the increase in the current, and a predetermined maximum value is obtained. As shown in FIG. 2, there is a non-linear region where the thrust is saturated where thrust cannot be obtained. This saturation phenomenon of the thrust is caused by a magnetic flux in which the magnetic flux of the permanent magnet 18 is superimposed on the magnetic flux generated by the armature winding 15 (meaning a magnetic flux proportional to the generated thrust, hereinafter referred to as “main magnetic flux”). Happens to saturate at. If the current is small, the thrust ensures linearity, but if a current corresponding to the main magnetic flux exceeding the saturation magnetic flux density of the inductor teeth 3 flows, the thrust becomes non-linear. Further, when the current is increased, the magnetic flux passing through the inductor teeth 3 is completely saturated, and the thrust does not change at all even if the current is increased. For this reason, in the case of the conventional linear motor, there is a problem that the required acceleration / deceleration performance cannot be obtained due to the above-described thrust saturation phenomenon, and a sufficient maximum thrust cannot be obtained for the motor size. Was. Therefore, in order to improve the linearity of the thrust of the linear motor, either the magnetic saturation of the inductor teeth 3 is suppressed or a magnetic pole structure that increases the magnetic flux density of the air gap between the armature 11 and the inductor 2 is adopted. Measures are needed. In the former case, the tooth width of the inductor teeth 3 for improving the linearity of the thrust is studied, and is already known. The latter is made possible by recent rare earth-based high-performance permanent magnets, but has not seen a dramatic improvement, and there is a need for another improvement. The present invention has been made to solve the above problems, and has a magnetic pole structure capable of increasing the magnetic flux density of the air gap between the armature and the inductor and greatly improving the maximum thrust as compared with the conventional art. An object is to provide a linear motor.

[0004]

In order to solve the above-mentioned problems, the present invention according to claim 1 is directed to an armature winding wound around the teeth of an armature core formed by laminating electromagnetic steel sheets and a tip end of the teeth. An armature having a plurality of arranged magnetic poles (the length per pole is a magnetic pole pitch Pm), and an inductor having an inductor tooth made of a magnetic material and opposed to the magnetic pole via a gap. In a linear motor that performs relative movement with one of the armature and the inductor as a mover and the other as a stator, the magnetic poles per pole are adjacent to each other such that the magnetization directions are alternately different. N (n
Is an integer of 2 or more). According to a second aspect of the present invention, in the linear motor according to the first aspect, the angle difference θ between the magnetization directions of n adjacent permanent magnets arranged in the magnetic pole per pole is set to θ = 1.
It is shifted by 80 ° / n. According to a third aspect of the present invention, in the linear motor according to the first aspect, when two permanent magnets are arranged in the magnetic pole per pole, one of the permanent magnets whose width in the magnetic pole pitch direction is Wa is used. The magnetization direction is made to coincide with the traveling direction of the mover, and the magnetization direction of the other permanent magnet whose width in the magnetic pole pitch direction is Wb is shifted by 90 ° with respect to the magnetization direction of the one permanent magnet. And the width Wb of the other permanent magnet is 0.3 ≦ Wb / Pm <1.0.
According to a fourth aspect of the present invention, in the linear motor according to the first aspect, when two permanent magnets are arranged in the magnetic pole per pole, the magnetization direction η1 of one permanent magnet is changed to the moving direction of the mover. And the magnetization direction η2 of the other permanent magnet is shifted by an angle of η2 = 180 ° −η1 with respect to the magnetization direction η1 of one of the permanent magnets. The width of each of the permanent magnets in the magnetic pole pitch direction is equal. According to a fifth aspect of the present invention, there is provided an armature winding wound around teeth of an armature core formed by laminating electromagnetic steel sheets and a plurality of magnetic poles (the length per pole is defined as a magnetic pole pitch). Pm), and an inductor having an inductor tooth made of a magnetic material and opposed to the magnetic pole with a gap therebetween, and one of the armature and the inductor is a mover. To
In a linear motor that performs relative movement using the other as a stator, the plurality of magnetic poles are constituted by permanent magnets that are multipolarly magnetized so that the magnetization direction becomes an arc toward the moving direction of the mover. .

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B show a linear motor according to a first embodiment of the present invention, wherein FIG. 1A is a side sectional view, and FIG. 1B is an enlarged view of a magnetic pole in FIG. The direction of the arrow (矢 印 ↓, etc.) in the figure indicates the magnetization direction of each permanent magnet.
In addition, the same reference numerals are given to the same components as those of the related art, and the description thereof will be omitted, and only different points will be described. In the figure, reference numeral 17a denotes a permanent magnet whose width in the magnetic pole pitch direction is Wa, and 17b denotes a permanent magnet whose width in the magnetic pole pitch direction is Wb. The differences between the present invention and the prior art are as follows. The number of magnetic poles per pole is n (n is 2 so that the magnetization direction is alternately different).
(The above integers) are disposed adjacent to each other, and the angle difference θ between the magnetization directions of the adjacent permanent magnets is set to θ = 180
This is a point shifted by ° / n. FIG. 1 shows a case where a magnetic pole per pole is composed of n = 2 permanent magnets 17a and 17b, and the angle difference θ in the magnetization direction is set to 90 degrees.
Specifically, the magnetization direction of one permanent magnet 17a is made to coincide with the traveling direction of the mover, and the other permanent magnet 17b
Is 90 ° with respect to the magnetization direction of the permanent magnet 17a.
And the relationship between the magnetic pole pitch Pm and the width Wb of the permanent magnet 17b is set to 0.3 ≦ Wb / Pm <1.0. The operation of the linear motor is basically the same as that of the prior art, and therefore will not be described.

Next, confirmation of the effect of the thrust characteristics according to the embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a diagram showing the relationship between the current flowing through the armature winding of the linear motor of the present invention and the prior art and the thrust. 3A and 3B are explanatory diagrams showing the flow of a main magnetic flux between a magnetic pole and an inductor tooth according to an embodiment of the present invention. FIG. 3A shows the first embodiment, and FIG. 3B shows the case of the prior art. As shown in FIG. 3B, the main magnetic flux in the prior art flows into the side and tip of the inductor tooth 3 separately. Due to the magnetic pole structure of the main magnetic flux flowing into the tip of the inductor tooth 3, the distribution of the main magnetic flux flowing in the moving direction of the mover is sparse. That is, the thrust is small. On the other hand, in the first embodiment, as shown in FIG. 3A, the distribution of the main magnetic flux flowing into the side surface and the tip of the inductor tooth 3 is controlled by the permanent magnet 17a whose magnetization direction is the traveling direction of the mover. Is dense. That is, it means that a larger thrust is obtained than in the prior art. Therefore, the first embodiment of the present invention employs the above-described magnetic pole structure to reduce the magnetic flux density of the air gap formed by the permanent magnets 17a and 17b, as shown in FIG. The maximum thrust can be greatly improved.

Next, the confirmation of the effect in the relationship between the width of the permanent magnet and the maximum thrust will be described. FIG. 4 shows the ratio (Wb / Wb / Wb) of the permanent magnet 17b to the magnetic pole pitch Pm.
6 is a graph showing the relationship between Pm) and the maximum thrust ratio of the present invention with respect to the prior art. In the figure, Wb / Pm <
At 0.3, it is lower than the prior art, and 0.3 ≦ Wb / Pm
In the range of <1.0, it can be confirmed that a maximum thrust greater than that of the related art is obtained. In particular, Wb / Pm =
Near 0.6, the maximum thrust increases by 10%.

Next, a second embodiment will be described. FIG.
FIG. 5 is an enlarged view of a magnetic pole according to the second embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
The direction of the arrow in the drawing indicates the magnetization direction of each permanent magnet, as in the first embodiment. The second embodiment is different from the first embodiment in that when two permanent magnets 17c and 17d are arranged in one magnetic pole, one permanent magnet 1c is disposed.
7c with respect to the moving direction of the mover at 0 ° <
While shifting by an angle of η1 <90 °, the magnetization direction η2 of the other permanent magnet 17d is shifted by an angle of η2 = 180 ° −η1 with respect to the magnetization direction η1 of one of the permanent magnets 17c. The point is that the widths Wc and Wd in the magnetic pole pitch direction are made equal. A second embodiment is:
Since the magnetic flux density in the air gap between the armature and the inductor increases as in the first embodiment, the maximum thrust can be improved as compared with the prior art. The permanent magnet used in the first embodiment has one permanent magnet 17a having the same magnetization direction as the moving direction of the mover, and the permanent magnet 17a has a magnetization direction of 9 mm.
Whereas two types of the other permanent magnet 17b shifted by 0 ° are required, the second embodiment can be constituted by one type of permanent magnet whose magnetization direction is symmetric with respect to the moving direction of the mover. The number of parts can be reduced, and the assembly of the magnetic pole can be facilitated. The operation of the linear motor is the same as that of the conventional example, and the reason for the improvement of the thrust is basically the same as that of the first embodiment.

Next, a third embodiment will be described. FIG.
FIG. 6 is an enlarged view of a magnetic pole according to the third embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
The direction of the arrow in the figure indicates the magnetization direction of each permanent magnet, as in the first and second embodiments. The third embodiment is different from the first and second embodiments in that the magnetic poles per pole have four permanent magnets 17e, 1e,
7f, 17g, and 17h are arranged adjacent to each other. In the third embodiment, as in the first and second embodiments, the magnetic flux density in the air gap between the armature and the inductor is increased, so that the maximum thrust can be improved as compared with the related art. Further, the third embodiment has a magnetic pole structure in which there is no irreversible demagnetizing effect due to a reverse magnetic field which easily occurs between the permanent magnets 17a and 17b having the orthogonal magnetization directions in the first embodiment. In the first embodiment, since the magnetization directions of the adjacent permanent magnets 17a and 17b are 90 degrees, the permanent magnet 17a serves as a source of a reverse magnetic field magnetomotive force, and partially applies a reverse magnetic field to the permanent magnet 17b. Therefore, in the third embodiment, a permanent magnet 17f whose magnetization direction is a 45 ° tilt direction is inserted between the permanent magnets 17e and 17g. As a result, the magnetization direction of the adjacent permanent magnet changes smoothly, and a magnetic pole structure without irreversible demagnetization can be formed. The operation of the linear motor is the same as that of the conventional example, and the reason for the improvement of the thrust is basically the same as that of the first embodiment.

Next, a fourth embodiment will be described. FIG.
FIG. 4 is an enlarged view of a magnetic pole according to a fourth embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.
The direction of the arrow in the drawing indicates the magnetization direction of each permanent magnet as in the first to third embodiments. The fourth embodiment is different from the first to third embodiments in that permanent magnets arranged in a plurality of magnetic poles are arranged so that the magnetization direction becomes an arc toward the moving direction of the mover. Polarized, 6
The point is that it is constituted by one pole-magnetized permanent magnet 17i. In the fourth embodiment, the maximum thrust can be improved with respect to the prior art as in the first to third embodiments. Further, in the fourth embodiment, since the plurality of magnetic poles are constituted by one permanent magnet, the number of parts can be significantly reduced, and the assembling of the magnetic poles is facilitated, and the mechanical strength of the magnetic poles is increased. I have. Note that the operation of the linear motor is the same as that of the conventional example, and the reason for the improvement of the thrust is basically the same as that of the first embodiment, and therefore will not be described.

In the above embodiment, the armature is arranged on the mover. However, the effect of the present invention can also be obtained by adopting a structure in which the armature is arranged on the stator side and the inductor is arranged on the mover. Needless to say, it can be demonstrated. Further, although the armature constituted by three teeth is shown, a similar effect can be obtained by connecting a plurality of them or a single armature having a plurality of teeth.

[0012]

According to the above configuration, the following effects can be obtained. (1) According to the first embodiment, the angle difference θ between the magnetization directions of n adjacent permanent magnets arranged in one magnetic pole is shifted from each other by θ = 180 ° / n. .
When two permanent magnets are arranged in the magnetic pole per pole, the width in the magnetic pole pitch direction is set to Wa, and the magnetization direction of one permanent magnet is made to coincide with the moving direction of the mover, and the width in the magnetic pole pitch direction is set. Is set to Wb, the magnetization direction of the other permanent magnet is shifted by an angle of 90 ° with respect to the magnetization direction of the one permanent magnet, and the relationship between the magnetic pole pitch Pm and the width Wb of the other permanent magnet is 0.3 ≦ Wb / Pm <1.0, so that the magnetization direction is 90 degrees with respect to the moving direction of the mover.
° The inverted permanent magnet increases the main magnetic flux that flows into the side and tip of the inductor teeth, thus increasing the magnetic flux density in the air gap between the armature and the inductor, increasing the thrust and maximum force at each current value compared to the conventional technology. Thrust can be improved.
In particular, when the width Wb of the other permanent magnet is 0.6 times the magnetic pole pitch, the maximum thrust can be improved by 10% as compared with the related art. (2) According to the second embodiment, the number of magnetic poles per pole is 2
When the permanent magnets are arranged, the magnetization direction η1 of one permanent magnet is set to 0 ° <η1 <90 with respect to the moving direction of the mover.
In addition to shifting the magnetization direction η2 of the other permanent magnet with respect to the magnetization direction η1 of one permanent magnet,
Because the widths Wc and Wd of the two permanent magnets in the magnetic pole pitch direction were made equal by shifting by 180 ° -η1,
Since the magnetic flux density in the air gap between the armature and the inductor increases as in the first embodiment, the maximum thrust can be improved as compared with the prior art. Furthermore, since all of them can be constituted by the same permanent magnet, the number of parts can be reduced and the assembly of the magnetic pole can be facilitated. (3) According to the third embodiment, the magnetic poles per pole are arranged adjacent to each other by using four permanent magnets having different magnetization directions from each other. Therefore, similar to the first and second embodiments, Since the magnetic flux density in the air gap between the armature and the inductor increases, the maximum thrust can be improved as compared with the related art. further,
This has the effect of preventing irreversible demagnetization between the permanent magnets whose magnetization direction is the traveling direction and the perpendicular direction. (4) According to the fourth embodiment, the permanent magnets arranged in the plurality of magnetic poles are multipolar magnetized so that the magnetization direction becomes an arc toward the moving direction of the mover. Because
Like the first to third embodiments, the maximum thrust can be improved with respect to the prior art. Furthermore, since the plurality of magnetic poles are constituted by one permanent magnet, the number of parts can be significantly reduced, the assembling of the magnetic poles is facilitated, and the mechanical strength of the magnetic poles can be increased.

[Brief description of the drawings]

FIG. 1 is a linear motor showing a first embodiment of the present invention, wherein (a) is a side sectional view and (b) is an enlarged view of a magnetic pole in (a).

FIG. 2 is a diagram showing a relationship between a current flowing through an armature winding of a linear motor according to the present invention and a prior art and a thrust.

FIGS. 3A and 3B are explanatory diagrams showing a flow of a main magnetic flux between a magnetic pole and an inductor tooth according to an embodiment of the present invention, wherein FIG. 3A shows the embodiment and FIG.

FIG. 4 shows a magnetic pole pitch Pm in the first embodiment of the present invention.
4 is a graph showing the relationship between the ratio of Wb of the permanent magnet 17b to the conventional technology (Wb / Pm) and the maximum thrust ratio of the present invention with respect to the prior art.

FIG. 5 is an enlarged view of a magnetic pole according to the second embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.

FIG. 6 is an enlarged view of a magnetic pole according to a third embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.

FIG. 7 is an enlarged view of a magnetic pole according to a fourth embodiment of the present invention, and corresponds to FIG. 1B of the first embodiment.

8 (a) is a side sectional view of a conventional linear motor, and FIG. 8 (b) is an enlarged view of a magnetic pole in FIG. 8 (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Stator 2 Inductor 3 Inductor tooth 10 Mover 11 Armature 12 Armature core 13 Teeth 14 Yoke 15 Armature winding 16 Magnetic pole 17a, 17b, 17c, 17d, 17e, 17f, 1
7g, 17h, 17i permanent magnet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H641 BB10 GG02 GG03 GG04 GG08 HH02 HH03 HH05 HH08 HH10 HH12 HH14 HH16 HH20 JA09

Claims (5)

[Claims] An armature winding wound around teeth of an armature core formed by laminating electromagnetic steel sheets and a plurality of magnetic poles (the length per pole is defined as a magnetic pole pitch P)
m), and an inductor having an inductor tooth made of a magnetic material and opposed to the magnetic pole with a gap therebetween, and one of the armature and the inductor is a mover. In a linear motor that performs relative movement using the other as a stator, n (n is an integer of 2 or more) permanent magnets are arranged such that the magnetic poles per pole are alternately arranged adjacently so as to have different magnetization directions. A linear motor characterized by comprising: 2. n arranged in the magnetic pole per pole
2. The linear motor according to claim 1, wherein angular differences θ between the magnetization directions of two adjacent permanent magnets are shifted from each other by θ = 180 ° / n. 3. When two permanent magnets are arranged in the magnetic pole per pole, the magnetization direction of one of the permanent magnets whose width in the magnetic pole pitch direction is Wa is made to coincide with the traveling direction of the mover. The magnetization direction of the other permanent magnet whose width in the magnetic pole pitch direction is Wb is shifted by 90 ° with respect to the magnetization direction of the one permanent magnet, and the relationship between the magnetic pole pitch and the width Wb of the other permanent magnet. 2. The linear motor according to claim 1, wherein 0.3 ≦ Wb / Pm <1.0. 3. 4. When two permanent magnets are arranged in the magnetic pole per pole, the magnetization direction η1 of one of the permanent magnets
Is shifted by an angle of 0 ° <η1 <90 ° with respect to the traveling direction of the mover, and the magnetization direction η2 of the other permanent magnet is set to η2 = 180 ° with respect to the magnetization direction η1 of one permanent magnet.
2. The linear motor according to claim 1, wherein the two permanent magnets are shifted by an angle of [eta] 1, and the widths of the two permanent magnets in the magnetic pole pitch direction are made equal. 5. An armature winding wound around teeth of an armature core formed by laminating electromagnetic steel sheets and a plurality of magnetic poles (the length per pole is defined as a magnetic pole pitch P).
m), and an inductor having an inductor tooth made of a magnetic material and opposed to the magnetic pole with a gap therebetween, and one of the armature and the inductor is a mover. In the linear motor performing relative movement with the other being a stator, the plurality of magnetic poles are constituted by multi-pole magnetized permanent magnets such that a magnetization direction becomes an arc shape toward a moving direction of the mover. A linear motor characterized by the following.