JP3473639B2 - Voice coil type linear motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field structure of a voice coil type linear motor, an armature winding system associated therewith, and a thrust shaft end and a fixing structure.

[0002]

2. Description of the Related Art As a voice coil linear motor of a first conventional example, two pairs of permanent magnets attached to the inner peripheral surface of an outer yoke are arranged in the axial direction with a gap between them so that their polarities are different from each other. The field and the inner diameter side of this field, through a gap,
A voice coil in which two cylindrical coils whose winding directions are opposite to each other are axially arranged at the pole pitch of the permanent magnet, and a central yoke made of a magnetic material is provided on the inner diameter side of the armature. There is a linear motor (for example, JP-A-61-1
No. 164459).

[0003]

However, in the prior art, since the magnetic flux generated by the permanent magnets passes through the yoke in one direction, the cross-sectional area of the yoke corresponds to the total amount of magnetic flux in order not to saturate the magnetic path. I just had to take it. It is an object of the present invention to reduce the size and weight of the yoke by reducing the cross-sectional area of the yoke to about half that of the conventional one without causing magnetic saturation, since the amount of magnetic flux in the air gap is the same.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, the inner peripheral surface of an outer yoke having a side yoke arranged only on one side is made axially with different polarities from each other and with a gap. A field magnet to which two sets of permanent magnets are attached, and two coils whose winding directions are opposite to each other on the winding bobbin with an air gap on the inner diameter side of the field magnet, at the pole pitch of the permanent magnet. A voice coil type linear motor in which an armature arranged in the axial direction and an inner yoke made of a magnetic material are provided on the inner diameter side of the armature, and an outer yoke and an end portion of the inner yoke are connected by a side yoke. The axial width of one of the permanent magnets is 1
When the axial width of the other permanent magnet is 2, the shorter one is arranged on the yoke tip side, and the longer one is arranged on the root side, and one axial width of the armature winding is 1. The other axial width is set to 2, the shorter one is arranged on the yoke tip side, and the longer one is arranged on the root side.

[0005]

By the above means, the magnetic flux produced by the permanent magnet is bifurcated to the left and right, the magnetic flux density of the yoke is reduced, the saturation of the magnetic circuit is prevented, the yoke can be made thinner than before, and the ampere turn produced by the armature winding is reduced. Although not cancelled, the permanent magnet can be thickened and the gap can be widened. Therefore, since the magnetic loading and the electrical loading can be large, a large thrust can be generated, the armature current / voltage can be reduced, and high efficiency can be achieved.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, numbers 11, 12, 13, and 14 are all ferromagnetic materials, and
Is an outer yoke in which a side yoke is arranged only on one side , 12 is an inner yoke, 13 is a side yoke, and 15a and 15b are permanent magnets for field. An outer yoke 11 made of a plate-like ferromagnetic material,
Inside 11 is three permanent magnets 15a, 15 of the same width.
a and 15b are magnetized in the axial direction by magnetizing the inner side of the distal permanent magnet 15b to the S pole, the inner side of the central permanent magnet 15a to the N pole, and the inner side of the root side permanent magnet 15a to the N pole. They are arranged with equal pitch. That is, the ratio of the width of the S pole of the permanent magnet 15b to the width of the N pole of the permanent magnets 15a, 15a is set to 1: 2. Nonmagnetic spacers 16, 16 are provided between the permanent magnets 15a, 15a, 15b. Outer yoke 1
1, the permanent magnets 15a, 15a, 15b and the spacer 16,
A set of field magnets 10 is constituted by 16, and the field magnets 10 and 10 are arranged to face each other. Between the field magnets 10 and 10, coils 18a and 18b whose winding directions are opposite to each other are wound around a hollow bobbin 17 made of a non-magnetic material in which the inner yoke 12 is inserted with a gap interposed therebetween. The armature 20 is arranged. Here, the ratio of the number of turns of the coils 18b and 18a is 1:
2, the axial width is also 1: 2. Short coil 1
The armature 20 is configured by facing 8b to the permanent magnet 15b and the long coil 18a to the permanent magnets 15a and 15a. An inner yoke 12 made of a ferromagnetic material fixed to the center of the side yoke 13 is arranged on the inner diameter side of the armature 20 with a gap. To one end of the armature 20, the end plate 14 side of a nonmagnetic material having a hole through which one end of the inner yoke 12 is inserted is fixed in the center. Both ends of the side yoke 13 are connected to one end of the outer yokes 11 and 11, and the other ends of the outer yokes 11 and 11 are opened. The end plate 14 side provided at one end of the armature 20 is arranged on the opening side. The armature 20 is supported by a bearing (not shown) so as to be movable in the axial direction, and is moved in the axial direction. The magnetic flux generated by the central permanent magnet 15a passes through the inner yoke 12-permanent magnet 15b-outer yoke 11 and returns to the central permanent magnet 15a. The magnetic flux generated by the permanent magnet 15a on the base side is the inner yoke 12-side yoke 13-
It passes through the outer yoke 11 and returns to the permanent magnet 15a on the root side. The magnetic flux produced by the coil 18a is twice the magnetic flux produced by the coil 18b, and most of it is consumed in the gap portion, but it circulates in the magnetic path described below, although it is very small. The magnetic flux generated by the coil 18a passes through the permanent magnet 15a-the outer yoke 11-the side yoke 13-the inner yoke 12 and returns to the coil 18a.
The magnetic flux generated by the coil 18b is half that of the magnetic flux generated by the coil 18a and has the opposite direction, so that the magnetic flux disappears. When an exciting current is passed through the coils 18a and 18b of the armature 20, thrust is generated in the armature 20. The armature 20 reciprocates by switching the exciting current between positive and negative. Figure 2
Is a second embodiment of the present invention. In order to increase the strength of the magnetic field portion of the embodiment against the magnetic attraction force,
1. One end of the inner yoke 12 is connected to the side yoke 13, and the other end is connected to the end plate 21 made of a non-magnetic material to form a box-shaped field structure. As shown in FIG. 3, a pair of nonmagnetic thrust plates 19 and 19 are fixed to the side surfaces of the bobbin 17 that do not face the field magnets 10 and 10 so as to be parallel to the axial direction. At the end of the thrust plate 19, an L-shaped flange 27 is provided on one side or both sides so as to be orthogonal to the axial direction of the bobbin 17. The flange 27 is adapted to go out from the opening on the side surface of the box-shaped field magnets 10, 10. FIG. 4 shows a third embodiment of the present invention, in which the permanent magnets 15a and 15b of the field magnet portion of the embodiment and the second embodiment are sandwiched by the armature 20 to provide 15c, 15c, 15c, 15c, 15d, 15d
It is provided separately. The polarity of the divided magnets is
Those facing each other have different polarities. By doing so, the degree of concentration of magnetic flux can be increased. In the embodiment and the second and third embodiments, the armature 20
Although the field magnet 10 is moved, the field magnet 10 may be moved.

[0007]

As described above, according to the present invention, the magnetic field and the magnetic flux generated by the coil are branched to the left and right of the yoke, so that the magnetic path cross-sectional area of the yoke can be made small. Loading becomes larger than that of the conventional technology, and high efficiency and high thrust can be achieved, and power consumption can be saved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing a second embodiment of the present invention.

FIG. 3 is a perspective view of a bobbin used in the second embodiment of the present invention.

FIG. 4 is a partial side sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

10 field 11 Outer yoke 12 Inner yoke 13 side yoke 14, 21 End plate 15a, 15b, 15c, 15d Permanent magnet 16 spacers 17 bobbins 18a, 18b coil 19 Thrust plate 20 armature 27 flange

Continuation of the front page (56) References JP-A-5-95662 (JP, A) Fukuihei 4-98875 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 33 / 18

Claims (4)

(57) [Claims] 1. A field magnet having two sets of permanent magnets arranged axially on the inner peripheral surface of an outer yoke having side yokes arranged only on one side and having polarities different from each other and having a gap therebetween. An armature in which two coils, whose winding directions are opposite to each other, are arranged in an axial direction at the pole pitch of the permanent magnet, on the inner diameter side of the field, with a gap therebetween, and the inside of this armature. In a voice coil type linear motor in which an inner yoke made of a magnetic material is provided and the outer yoke and the end portion of the inner yoke are connected by a side yoke, one of the two permanent magnets has an axial width of one. When the axial width of the other permanent magnet is 2, and one axial width of the armature winding is 1,
The voice coil type linear motor is characterized in that the axial width of the other side is 2, and the permanent magnet and the coil are arranged such that the shorter one is on the yoke tip side and the longer one is on the root side. 2. The voice coil type linear motor according to claim 1, wherein an end plate of a non-magnetic member is provided at the other ends of the outer yoke and the inner yoke. 3. A voice coil type linear motor according to claim 2, wherein a flange formed by bending a non-magnetic plate into an L shape is fixed to the winding bobbin, and the flange is extended outside from the opening of the field. 4. The voice coil type linear motor according to claim 1, wherein the permanent magnet is divided into upper and lower parts with the coil interposed therebetween.