JP2003164135A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inexpensively a linear motor having small magnetic loss and good volume efficiency. <P>SOLUTION: A cylindrical outer yoke 3 comprising the outer yoke section 1 is provided with 8 columns of equidistant through-holes 3a placed circumferentially. A winding 4a and a winding 4a wound separately in two sections are secured on the surface of the inner perimeter of each through-hole 3a and contained in a holding frame 8. The inner yoke section 2 is provided with 8 inner yokes 5, each penetrating a through-hole 3a of the outer yoke 3 and having each end integrated with a connecting plate 7. An axis 7a of the connection plate 7 is supported by a sleeve 9a of the side plate 9 installed on the opening at each end of the holding frame 8 to allow relative movement. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil type linear motor most suitable for industrial use.

[0002]

2. Description of the Related Art The applicant of the present invention has a voice coil type in which magnets adjacent to each other are made to have different single poles, and currents of different directions are applied to coils of linear motors adjacent to each other to move relative to each other. The application of the linear motor is filed first, and an example thereof will be described.

In FIG. 4, 41 is an inner yoke, 42 is a coil, 43 is an outer yoke, 44 is a magnet, and 45 is a magnetic path of the magnet 44.

The coil 42a and the coil 42b are wound around a cylindrical inner yoke 41a, and the coil 4 is wound on the adjacent inner yoke 41b.
2b and a coil 42a, which are adjacent to each other
It is arranged so that the directions of the electric currents flowing in a and the coil 42b are opposite to each other, and the fixed side is provided.

On the other hand, in the hollow portion of the outer yoke 43a, a magnet 44a whose inner peripheral surface is magnetized as an N pole, on the other side is a magnet 44b whose inner peripheral surface is magnetized as an S pole, and a magnet 44b is provided on an adjacent outer yoke 43b. The magnets 44a are adhered to each other so that the inner peripheral surface or the outer peripheral surface of the magnets adjacent to each other are formed into different single poles so as to be movable.

The outer yokes 43a and 43b are slidably supported by the inner yokes 41a and 41b with a constant air gap (not shown).

The magnetic fluxes of the magnetized magnets 44a and 44b are the inner yokes 41a and 41b and the outer yokes 43a and 43b.
The closed magnetic circuit 45 is formed via the space.

When the coils 42a and 42b are energized, the outer yoke moves in the direction determined by the direction of the coil current and the direction of the magnetic flux of the magnet that links the coil (arrow J direction). At this time, since the mutual magnetomotive forces are offset from each other, the magnetic flux density of the inner yoke 41 can be reduced.

However, as shown in FIG. 5, magnetic saturation is likely to occur in the thin portion A of the outer yoke, and magnetic saturation is difficult to occur in the thin portion B.

[0010]

As described above, in the above-described conventional structure, the magnetic flux density of the inner yoke is improved and a large thrust can be obtained, but local magnetic saturation is likely to occur in the outer yoke.

As a countermeasure against this, it is sufficient to increase the thickness of the outer yoke, but on the contrary, there is a problem that the weight of the linear motor becomes heavy and the volume efficiency decreases.

Further, if the thickness of the magnet other than the thin-walled magnet is increased, the volumetric efficiency can be prevented from lowering, but there is a problem that the amount of magnet used increases and the linear motor becomes expensive.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a linear motor having a small magnetic loss and a high volume efficiency at a low cost.

[0014]

In order to solve the above problems, the linear motor of the present invention has a columnar linear motor portion in which windings and magnets are opposed to each other at their circumferential surfaces, and the linear motor portions are adjacent to each other. The magnet inner peripheral surface or outer peripheral surface is made to have different single poles, and electric currents of different directions are caused to flow through the windings of the linear motor portions adjacent to each other to obtain thrust in the same direction and relatively move.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above-mentioned problems, the linear motor according to claim 1 is arranged such that a columnar linear motor portion in which a winding and a magnet are opposed to each other on a circumferential surface is annularly arranged and relatively moved. It is possible to suppress local magnetic saturation of the annularly arranged outer yoke, and to obtain a large thrust.

In the linear motor according to the second aspect of the present invention, a columnar linear motor portion in which a winding and a magnet are opposed to each other on the peripheral surface is annularly arranged, and the magnet inner peripheral surface or outer peripheral surface of adjacent linear motor portions is arranged. With different single poles, currents in different directions are made to flow through the windings of the linear motor parts that are adjacent to each other to obtain thrust in the same direction and move relative to each other.
It is possible to suppress local magnetic saturation of the annularly arranged outer yoke, and to obtain a large thrust.

According to a third aspect of the present invention, the linear motor has a magnet arranged on the movable side of the linear motor portion.
It is possible to prevent disconnection in power supply to the winding.

According to a fourth aspect of the present invention, in the linear motor, the outer yoke portion having a through hole through which a plurality of inner yoke portions penetrate is configured in multiple stages and is divided for each stage. After forming a plurality of the above, the outer yoke portion having a multi-stage structure can be obtained by simply arranging the through holes one by one and combining them.

Further, in the linear motor according to the fifth aspect, the outer yoke having the through-holes through which the plurality of inner yoke portions penetrate is formed by laminating electric iron plates, so that the reduction of magnetic loss can be prevented. Further, even if the through hole has a polygonal shape, it can be easily formed.

A linear motor according to a sixth aspect of the present invention is a cylinder driving device driven by the linear motor and a resin molding machine equipped with the cylinder driving device, and has a small magnetic loss, a small size and a light weight, and a large thrust. Obtainable.

[0021]

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 is a linear motor in which eight linear columnar motor portions are evenly arranged in a ring shape and two stages are stacked in the moving direction. Here, a portion constituted by a winding in one section and a magnet circumferentially opposed to the winding is referred to as a linear motor section to distinguish it from a linear motor.

In FIG. 1, 1 is an outer yoke portion, 2 is an inner yoke portion, 3 is an outer yoke, 4 is a winding wire, 5 is an inner yoke, 6 is a magnet, 7 is a connecting plate, 8 is a holding frame, and 9 is It is a side plate. Further, the lower half of FIG. 1 shows a cross section of adjacent linear motor portions.

The linear motor is roughly divided into an outer yoke portion 1 and an inner yoke portion 2. Outer yoke part 1
Is composed of an outer yoke 3, a winding wire 4, and a holding frame 8.

The cylindrical outer yoke 3 is provided with eight rows of through holes 3a, which are evenly arranged, in a ring shape, and the winding 4a and the winding 4a which are wound in two sections on the inner peripheral surface of each through hole 3a. 4b is fixed. Further, the through hole 3b is provided in the center to reduce the weight. Then, it is stored in the holding frame 8.

The inner yoke portion 2 is composed of an inner yoke 5, a magnet 6 and a connecting plate 7, and is provided with eight inner yokes 5 to which the magnet 6 is fixed, each penetrating a through hole 3 a of the outer yoke 3. Then, both ends of each are integrated by the connecting plate 7.

The sleeves 9a of the side plates 9 attached to the openings of both ends of the holding frame 8 support the shaft portion 7a of the connecting plate 7 to enable relative movement.

Although not shown, in order to maintain the gap between the inner yoke 5 and the through hole 3a so as not to move in the radial direction, spline processing is applied between the shaft portion 7a and the sleeve 9a, and the magnet and Prevents contact with the winding.

The winding 4 is formed on the outer peripheral surface of the cylindrical inner yoke 5.
The radially magnetized magnet 6 is adhered and fixed corresponding to the divided two sections. At this time, the magnets 6 are arranged such that the outer peripheral surfaces (or inner peripheral surfaces) of the adjacent magnets 6 have different single poles. As a result, 16 linear motor units are configured.

Now, with reference to FIG. 2, the circulation will be described centering on the main magnetic flux emitted from the N pole of one magnet.
Outer peripheral surface (or inner peripheral surface) of adjacent magnets
Are configured with different single poles, the same magnetic flux flows between other yokes.

First, half of the magnetic flux radially emitted from the N pole of the outer peripheral surface of the magnet 6a bonded to the inner yoke 5a (the right half on the extension line connecting the center of the outer yoke and the center of the inner yoke in FIG. 2).
Passes through the facing gap (through hole 3a) to the outer yoke 3, and then passes through the outer yoke 3 and the adjacent inner yoke 5
The magnetic flux reaching the S pole of the outer peripheral surface of the magnet 6c provided on the b side and coming out from the N pole of the inner peripheral surface of the magnet 6c is supplied to the inner yoke 5
It passes through b and reaches the S pole of the inner peripheral surface of the adjacent magnet 6d.

Further, the magnetic flux radially emitted from the N pole of the outer peripheral surface of the magnet 6d reaches the outer yoke 3 through the facing gap, passes through the outer yoke 3 and the inner yoke 5a.
To the S pole of the outer peripheral surface of the magnet 6b. Then, the magnetic flux emitted from the N pole of the inner peripheral surface of the magnet 6b passes through the inner yoke 5a and returns to the S pole of the inner peripheral surface of the original magnet 6a to form a closed magnetic path.

On the other hand, the magnetic flux of the other half (left half in FIG. 2) radially emitted from the N pole of the outer peripheral surface of the magnet 6a bonded to the inner yoke 5a is similarly generated by the magnet 6e provided on the opposite inner yoke 5c. This magnet 6 reaches the S pole on the outer peripheral surface.
The magnetic flux emitted from the N pole of the inner peripheral surface of e passes through the inner yoke 5c and reaches the S pole of the inner peripheral surface of the adjacent magnet 6f.

Further, the magnetic flux radially emitted from the N pole of the outer peripheral surface of the magnet 6f reaches the outer yoke 3 through the facing gap, passes through the outer yoke 3 and the inner yoke 5a.
To the S pole of the outer peripheral surface of the magnet 6b. The magnetic flux emitted from the N pole of the inner peripheral surface of the magnet 6b passes through the inner yoke 5a and returns to the S pole of the inner peripheral surface of the original magnet 6a to form a closed magnetic path.

In this way, a similar closed magnetic path is formed between the outer yoke and the inner yoke adjacent to each other. However, since the magnetic flux emitted radially branches left and right at the thin portion on the extension line connecting the center of the outer yoke and the center of the inner yoke, the magnetic flux passing through the thin portion is reduced to half that of the conventional example, and magnetic saturation hardly occurs ( (Fig. 2).

That is, the thickness of the outer yoke can be reduced, and the size and weight can be reduced. In other words, the magnetic motor has good magnetic efficiency and volume efficiency, and is an inexpensive linear motor.

Next, the operation when a current is passed through the winding will be described.

The winding is in the closed magnetic circuit described above and is wound so as to be orthogonal to the magnetic flux. Here the windings 4a, 4
When currents of different directions are applied to b, thrust is generated according to Fleming's left-hand rule. In order to make this thrust in the same direction, the magnetic poles of the magnets adjacent to each other are arranged in reverse.

By the way, even if either side of the outer yoke part or the inner yoke part is fixed, the opposite side moves, but fixing the winding side (outer yoke part) is a wiring part for supplying power to the winding. Can be prevented from breaking.

The winding 4 wound around one inner yoke
Since currents flowing in different directions flow through a and 4b, the magnetomotive forces of the currents are in opposite directions and cancel each other out. Therefore, the magnetic saturation in the inner yoke is relaxed, and the linear motor can maintain the linearity of the current and the thrust up to the high thrust region.

The linear motor of the first embodiment has a linear motor portion formed in an annular shape with 8 rows and 2 stages.
The present invention can be similarly implemented with a multi-stage structure having three stages or more. It is also possible to change from 8 rows to 4 rows or 6 rows. In any case, the magnets adjacent to each other may be arranged such that the outer peripheral surfaces (or inner peripheral surfaces) thereof have different single poles, and the directions of the currents flowing in the windings adjacent to each other may be reversed.

Further, regarding the relationship between the magnet in the thrust direction for determining the stroke and the length of the winding, the magnet is longer.

In the first embodiment, the integral outer yoke has been described, but only the outer yoke is divided into units of one stage (8 rows),
A multi-stage configuration of the outer yoke portion can be easily realized by combining the windings while paying attention to the direction of the current.

Further, an electric iron plate whose surface is insulated may be laminated and pressed to form an outer yoke, which can reduce magnetic loss when high-speed reciprocating drive and high thrust are required.
Furthermore, when the through holes are polygonal and are large in number, the outer yoke can be constructed at low cost.

Further, although the cylindrical inner and outer yokes are used for the description, a hexagonal prism or an octagonal prism can be used. In particular, when using a magnet having a high magnetic flux density, a plurality of arc-shaped, rod-shaped or plate-shaped magnets may be fixed.

The above contents can be carried out either alone or in combination.

(Embodiment 2) In Embodiment 2, a magnet is arranged on the outer yoke portion and a winding is arranged on the inner yoke portion.
The arrangement is the reverse of that of the first embodiment.

In FIG. 3, 31 is an outer yoke portion, 32 is an inner yoke portion, 33 is an outer yoke, 34 is a magnet, and 35.
Is an inner yoke, 36 is a winding wire, 37 is a connecting plate, 38 is a holding frame, and 39 is a side plate 38.

Also in the second embodiment, the magnets 34 adjacent to each other are arranged such that the inner peripheral surfaces (or outer peripheral surfaces) thereof have different single poles, and the directions of the currents flowing through the windings 36 adjacent to each other are reversed. . In addition, the thrust generated by the direction of the current flowing through the winding that intersects with the magnetic flux can be made to be in the same direction, but the idea is the same as that of the first embodiment except that the magnet and the winding are reversed, and a description thereof will be omitted. To do.

As described above, it is possible to inexpensively obtain a small-sized and lightweight linear motor which has small magnetic saturation and magnetomotive force loss, and has good magnetic efficiency and volume efficiency.

For example, if the linear motor of the present invention is used for applications requiring a large thrust such as cylinder driving of a resin molding machine, the apparatus can be simplified and the size and weight can be reduced.

[0052]

As is apparent from the above-described embodiments, according to the first, second and third aspects of the present invention, magnetic saturation in the outer yoke can be suppressed, so that a small and lightweight linear motor with less magnetic loss can be obtained. To be Further, it is possible to prevent disconnection of the winding wire during power feeding, and to obtain a highly reliable linear motor.

According to the inventions of claims 4 and 5,
It is possible to easily obtain the outer yoke portion having a multi-stage structure. Further, magnetic loss can be reduced and a high-thrust linear motor can be obtained at low cost.

Further, in the cylinder drive device equipped with the linear motor of the present invention and the resin molding machine equipped with the cylinder drive device, the cylinder drive device can be simplified by directly connecting the linear motor movable portion to the cylinder. Moreover, since this linear motor is small and can obtain a large thrust, the resin molding machine can be downsized.

As described above, the number of arrays of the linear motor section can be changed according to the application, and a linear motor which is small and lightweight and has little loss can be obtained, which is optimum for industrial applications.

[Brief description of drawings]

FIG. 1 is a structural diagram of a linear motor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of magnetic saturation reduction in Example 1 of the present invention.

FIG. 3 is a structural diagram of a linear motor according to a second embodiment of the present invention.

FIG. 4 is a structural diagram of a conventional linear motor

FIG. 5 is an explanatory diagram of magnetic saturation in a conventional linear motor.

[Explanation of symbols]

3,33 outer yoke 3a through hole 4,36 windings 5,35 Inner yoke 6,34 magnet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsunemitsu Suehiro             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H002 AA03 AA05                 5H633 BB02 GG03 GG06 GG09 GG13                       HH02 HH06 HH13 JA10

Claims (7)

[Claims] 1. A linear motor in which a columnar linear motor portion in which a winding and a magnet are opposed to each other on a peripheral surface is annularly arranged and relatively moves. 2. A thrust force in the same direction can be obtained by making different inner poles or outer circumferential surfaces of magnets of adjacent linear motor sections into different single poles and passing different directions of current through windings of adjacent linear motor sections. The linear motor according to claim 1, wherein the linear motor is relatively moved. 3. The linear motor according to claim 1, wherein a magnet is arranged on the movable side of the linear motor portion. 4. The linear motor according to claim 1 or 2, wherein the outer yoke portion having a through hole through which a plurality of inner yoke portions penetrate is configured in multiple stages and is divided for each stage. 5. The linear motor according to claim 1, 2 or 4, wherein the outer yoke having a through hole through which the plurality of inner yoke portions penetrate is formed by laminating electric iron plates. 6. A cylinder drive device driven by the linear motor according to any one of claims 1 to 5. 7. A resin molding machine equipped with the cylinder drive device according to claim 6.