JP3791082B2 - Linear motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stepping motor, a servo motor, or a direct drive motor that is driven at a low speed and moves linearly.
[0002]
[Prior art]
Conventionally, it has been known that if a field of a pulse motor is given by a permanent magnet, high thrust can be obtained with a compact configuration, and various structures are considered. Among them, Japanese Patent Application Laid-Open No. Sho 63-310361 discloses an improvement in the responsiveness and damping characteristics of the mover, which can simplify lead wire processing and can be manufactured at low cost. The structure of the linear motor is described in detail in the publication, but is generally as follows.
A linear stator with a U-shaped cross-section and opened upward has two U-shaped yokes with the same cross-section arranged in parallel on the inside, and the coils are arranged in the longitudinal direction at the bottom of the yoke. It is wound. The two yokes each have two magnetic poles extending upward. A magnetic pole plate is fixed to the top surface of each magnetic pole. Protruding pole teeth extend at equal intervals toward the other magnetic pole plate. Opposing pole teeth are staggered to form a claw pole type magnetic pole surface. There is no. The movable element supported so as to be movable in the longitudinal direction of the stator is provided with two sets of permanent magnets parallel to each other so as to face the magnetic pole surface through an air gap, and is the same as the protrusion of the magnetic pole plate. It is magnetized so that the polarity is reversed at intervals. In such a configuration, when a two-phase sine wave current having a phase difference of 90 degrees is supplied to the coils wound around the two yokes, the mover moves over the stator by a widely known linear motor mechanism. It can move in the longitudinal direction.
[0003]
[Problems to be solved by the invention]
However, according to the above prior art, there are the following problems. That is, since the two yokes and the magnetic pole plate provided on the stator have the structure as described above, the yoke must be formed of a massive iron core, and the magnetic pole plate must be formed of a thin soft magnetic steel plate. Increasing the excitation current flowing through the coil causes magnetic saturation and suppresses the peak thrust of the motor, and increasing the moving speed of the mover increases the iron loss of the magnetic pole plate. In addition, since the leakage of magnetic flux passing through the gap between the pole teeth of the pole plates that are staggered extending from the upper surfaces of the two yokes is large as a whole, the motor thrust is small with respect to the excitation current, that is, the motor constant is small. There were drawbacks. Further, since a magnetic attractive force is generated between the stator and the mover, there is a drawback that a large load is applied to the support mechanism of the mover, and the structure is distorted to cause various adverse effects.
[0004]
[Means for Solving the Problems]
The present invention has been made to solve these drawbacks, and an object of the present invention is to provide a motor that is reliable and can provide high thrust.
Accordingly, the present invention provides a rod-shaped permanent magnet having a rectangular cross-section with different polarities at a pitch P, a table having the permanent magnet fixed thereto, and a support means for movably supporting them, and the magnetic poles having an air gap. In an m-phase linear motor that moves the mover by alternating current excitation of the stator, an upper portion of one side of the rectangle is formed. C-shaped iron cores having the same shape and formed with magnetic poles having parallel magnetic pole faces facing each other are arranged at a pitch of 2P with the permanent magnets sandwiched between the magnetic poles, and one coil is wound around the iron core in common. A single-side magnet unit is formed, and the two single-side magnet units are opposed to each other, and the magnetic poles are arranged so as to be aligned in a line at a pitch P from each other to form a stator unit. Pitch of adjacent iron cores (P + P / m) (m = 2,3,4, ···) and arranged plurality so that it had a linear motor of m phases form a stator.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In this way, the stator iron core can be laminated with silicon steel sheets and the magnetic path cross section can be made larger than before, so that magnetic saturation is less likely to occur and the peak thrust of the motor is increased. can do. In addition, since the magnetic attractive force acting between the mover and the stator is offset, the burden on the support mechanism is reduced, and the reliability can be improved and the mechanism can be simplified.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a two-phase linear motor showing a first embodiment of the present invention, and FIG. 2 is a plan view with a part thereof omitted. In the figure, reference numeral 1 denotes a base, on which stator units 21 and 22 are mounted to form a stator 2. Each of the stator units 21 and 22 includes two one-side magnet units 31A and 31B and 32A and 32B having the same configuration, and the one-side magnet unit 31A includes two C-shaped iron cores 41 and 43 having the same shape. The C-shaped iron core 41 is formed by laminating silicon steel plates, and cuts the upper part of one side of a rectangle to form magnetic poles 511 and 512 having parallel magnetic pole faces facing each other. The shaped C-shaped iron cores 43 are arranged in parallel so that the distance between the centers of the iron cores is 2P. A coil 61 is wound in common on the lower sides of both iron cores, and laid sideways so that the magnetic pole surface is on the upper side and fixed to the base 1 to form a one-side magnet unit 31A. The magnet unit 31B is configured in the same manner, and the magnetic pole surfaces of the magnetic poles 511, 522, 531, and 542 of the C-shaped iron cores 41, 42, 43, and 44 and the magnetic pole surfaces of the magnetic poles 512, 521, 532, and 541 are linearly arranged. They face each other in parallel. The stator unit 21 and the stator unit 22 having the same configuration have a center-to-center distance of 4.5 P, and the center-to-center distance between adjacent C-shaped iron cores is 1.5 P, and the magnetic pole surfaces are the same. They are placed on a flat surface. Between the magnetic poles 511, 522, 531, 542 and 512, 521, 532, 541 of the C-shaped iron cores 41, 42, 43, 44, a rod-shaped permanent magnet 7 having a square cross section is arranged and fixed to a table (not shown). ing. The table is supported by a support mechanism (not shown) so as to be movable in the left and right movement directions to form a movable element 8. The permanent magnet 7 is magnetized in the direction toward each magnetic pole surface of the C-shaped iron core, and the direction of magnetization is reversed at a pitch P in the longitudinal direction.
[0006]
In the above configuration, the situation when the current is supplied to the coils 61 and 62 of the stator unit 21 in the direction shown in FIG. As shown in FIGS. 3A and 3B, the magnetic flux passing through the C-shaped iron cores 41 and 42 is added in accordance with the magnetization direction of the permanent magnet 7. Since the polarity of the permanent magnet 7 and the polarity of the magnetic pole of the C-shaped iron core facing each other through the air gap are different and magnetic attractive force is generated, the moving direction position of the mover 8 is stably held in the state of FIG. The sum of the magnetic attractive forces is canceled and becomes zero because the attractive forces of the two magnetic poles of the two C-shaped iron cores are equal and in opposite directions.
Next, the operation when switching the excitation of the stator units 21 and 22 will be described with reference to FIG. FIG. 4 shows the state of excitation of the stator 1 divided into four steps, and the state of the magnetic pole being excited is viewed from above. (A) is in the same excitation state as described with reference to FIGS. 2 and 3, and the stator magnetic poles and the mover magnetic poles facing each other have different polarities and are stably held by the magnetic attractive force. (B) shows the state when a current is supplied to the stator unit 22 in the same manner as the current supplied to the stator unit 21 in (a). For the same reason as (a), (a) On the other hand, the mover 8 is stably held at a position moved 0.5P to the right. (C) shows a state in which a current having a direction opposite to that in the case of (a) is supplied, and is stably held at a position moved to the right by 0.5P with respect to (b). (D) has shown the state which supplied the electric current of the reverse direction to the case of (b), and is stably hold | maintained in the position which moved 0.5P right with respect to (c). By switching the current for one cycle, which returns to (a) after going through the four steps from (a) to (d), the mover 8 can move to the right by 2P. It can be moved continuously to the right. Needless to say, if the current is switched in the reverse order, the movable element 8 can be moved to the left by the same mechanism.
[0007]
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5A is a plan view of the linear motor of the second embodiment with a part thereof omitted, and FIG. 5B is a cross-sectional view taken along line AA ′ of FIG. The second embodiment is similar to the first embodiment except for a part, and only different points will be described. One of the changes is that the C-shaped iron core 41 of the first embodiment is divided into a C-shaped iron core 451 and an I-shaped iron core 461, and two sets of magnetic pole surfaces 551 and 552 facing each other are parallel to each other. It is rigidly fixed to the base 1 so that it becomes. Another change is in the mover 8, and permanent magnets 72 and 71 are directly or indirectly fixed to a table (not shown) with a nonmagnetic material 73 in between so as to be positioned between the two sets of magnetic pole surfaces. Yes. The permanent magnets 71 and 72 and the C-shaped iron core and the I-shaped iron core form a closed magnetic circuit. The C-shaped iron cores 452, 453, and 454 are the same as the C-shaped iron core 451, the I-shaped iron cores 462, 463, and 464 are the same as the I-shaped iron core 461, and the one-side magnetic pole units 33A and 33B constituted by them are the first embodiment. This corresponds to the one-side units 31A and 31B in the example. The operation of the linear motor of the second embodiment having such a configuration is the same as that of the first embodiment because the magnetic flux generation state of the stator 2 is the same as that of the first embodiment. Compared to the first embodiment, the area of the opposing magnetic pole surfaces of the stator 2 and the mover 8 is approximately doubled, so that the thrust is doubled.
In the two embodiments described above, the case where there are two one-side magnet units has been described, but three or more magnet units may be used. The two embodiments are two-phase linear motors, but three stator units are provided and the center-to-center distance is 16 P / 3, that is, the center-to-center distance between adjacent iron cores is 4 P / 3. Phase linear motor. Similarly, if m stator units are provided and the distance between the centers is (P + P / m), an m-phase motor can be obtained. In both cases, the current is switched in both directions as in the case of the two-phase motor. Can be moved.
[0008]
【The invention's effect】
As described above, according to the present invention, since the silicon steel plates are laminated to form the C-shaped iron core or I-shaped iron core of the stator, the area of the magnetic path can be increased compared to the conventional one, Magnetic saturation hardly occurs and high thrust can be obtained. Moreover, since the silicon steel plates are laminated in the direction in which the iron cores are arranged, the leakage magnetic flux between the iron cores is small, and the reduction in thrust is minimized. If the permanent magnet of the mover is thinned, the magnetic field modulation factor increases, and thus a high thrust can be obtained. Furthermore, since the magnetic attractive force acting between the stator and the mover is canceled by both side surfaces of the permanent magnet, the burden on the support mechanism of the mover is small, and there is an effect that the reliability of the linear motor is improved.
[0009]
[Brief description of the drawings]
FIG. 1 is a perspective view of a linear motor showing a first embodiment of the present invention. FIG. 2 is a plan view of the first embodiment. FIG. 3 is an explanatory view of the first embodiment. [Fig. 5] Structural diagram of the second embodiment [Explanation of symbols]
1 Base 2 Stator 21, 22, 23, 24 Stator unit 31A, 31B, 32A, 32B, 33A, 33B, 34A, 34B One side magnet unit 41, 42, 43, 44, 451, 452, 453, 454 C type Iron cores 461, 462, 463, 464 I-type iron cores 511, 512, 521, 522, 531, 532, 541, 542, 551, 552 Magnetic poles 61, 62 Coils 7, 71, 72 Permanent magnet 73 Non-magnetic material 8 Movable element

Claims (1)

A mover comprising a rod-shaped permanent magnet having a rectangular cross section with different polarities at a pitch P, a table to which the permanent magnet is fixed, and a supporting means for movably supporting these;
The magnetic pole comprises a stator having a plurality of electromagnets sandwiching the permanent magnet through an air gap,
In an m-phase linear motor that moves the mover by AC excitation of the stator,
C-shaped iron cores having the same shape and formed with magnetic poles having parallel magnetic pole faces facing each other by cutting out the upper part of one side of the rectangle are arranged at a pitch of 2P with the permanent magnet sandwiched between the magnetic poles,
One coil is wound around the iron core to form a one-side magnet unit,
The two magnetic units on one side are opposed to each other, and the magnetic poles are arranged so as to be aligned in a row with a pitch P shift from each other.
M-phase linear, characterized in that a plurality of the stator units are arranged side by side so that the pitch of the adjacent iron cores is (P + P / m) (m = 2, 3, 4,...). motor.

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