JP3369328B2 - Voice coil type linear motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil type linear motor and, more particularly, to a magnetic circuit and a structure for reducing leakage magnetic flux of a coil. 2. Description of the Related Art As a first prior art, in order to align the windings of a coil for a voice coil motor, a voice having a coil portion formed by winding a wire into a laminated coil and a coating resin covering the outer surface of the coil portion. There is a coil for a coil motor in which the wires at the tip of the coil portion are laminated in a stepwise manner (for example, Japanese Utility Model Laid-Open No. 1-150474). Further, as a second conventional technique, a plurality of flat outer yokes opposed to each other with a space therebetween are arranged on the inner side in the axial direction and outside a central yoke provided between the outer yokes so that adjacent magnetic poles are alternately different. There is one in which permanent magnets for field are arranged to face each other (for example, Japanese Utility Model Laid-Open No. 4-98876). However, when the coil of the first prior art is applied to the magnetic circuit of the second prior art, since the end of the coil is chamfered on only one side,
Imbalance occurs in the magnetic flux leaking from the end of the coil end without chamfering to the outer yoke and the center yoke, and the vertical electromagnetic force (side force) becomes non-uniform, which tends to cause pitching. Accordingly, an object of the present invention is to provide a field permanent magnet and a coil in which leakage magnetic flux is less likely to be generated at an end portion and the magnetic flux distribution in the vertical direction is uniform, and to provide a linear motor in which pitching is less likely to occur. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a method in which a pair of flat outer yokes opposed to each other with a space therebetween are disposed axially inside and outside a central yoke provided between the outer yokes. In a linear motor in which a plurality of permanent magnets are arranged to face each other so that adjacent magnetic poles are alternately different, and a pair of coils having chamfered end faces are arranged between the permanent magnets, the outer yoke and the central yoke Of the provided permanent magnets, those arranged at both ends in the axial direction are provided with chamfered portions at the outer ends, or chamfered on both the inner and outer surfaces of the pair of coils at the outer ends in the axial direction to constitute a voice coil type linear motor. . According to the above-mentioned means, the leakage magnetic flux at the end is reduced, and the interlinkage magnetic flux between the magnetic flux of the field magnet and the magnetic flux generated by the coil near the end is reduced as compared with the prior art, so that the generation of side force is reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. Reference numeral 1 denotes a sun-shaped yoke made of a ferromagnetic material.
1 and 11, a closed yoke 12, which closes both ends of the outer yokes 11, 11, and a central yoke 13 which connects the center of the side yokes 12, 12. On the inner surfaces of the outer yokes 11, 11 and the outer surface of the central yoke 13, permanent magnets 14, 14, 15, 15 for field are provided.
The polarities of the adjacent one and the opposing one are alternately reversed, and are provided at a predetermined pitch in the axial direction. Permanent magnet 1
At both ends and inside of 4, 14 and both ends and outside of 15 and 15,
A chamfer C1 is provided. With the above configuration, the magnetomotive force distribution at the ends of the permanent magnets 14 and 15 becomes smaller toward the outside in the axial direction, and the gap at the ends is large. 1
Leakage magnetic flux to 1, 12, and 13 can be prevented. In addition, in order not to increase the types of permanent magnets, the permanent magnets 14 and 15 may be unified to the permanent magnets 14a and 15a arranged at both ends in the axial direction. Between the permanent magnets 14, 14 and 15, 15, the width W
1, a pair of coils 2 wound with a good conductor such as a circular or square tubular copper wire having a chamfer C2 at the outer end in the axial direction, while leaving a straight portion of 1
2 are provided at the same pitch as the pitch of the permanent magnets 14, 14, and are connected so that the currents flowing through the adjacent coils are reversed. Note that chamfered portions C2 may be provided at both ends of the coil 2 in order to make the coil shape symmetrical and facilitate manufacture. With the configuration described above, the coil end portion of the coil 2 and the outer yokes 11, 11 and the central yoke 1
The gap with the coil 3 becomes large, and the leakage of the magnetic flux generated by the coil 2 can be prevented. A bobbin 3 made of a non-magnetic material is fitted on the inner diameter sides of the coils 2 and 2. The bobbin 3 may be fitted on the outer diameter side of the coils 2 and 2. FIG. 2 shows a second embodiment in which the chamfers at the ends of the coils 2 and 2 are formed in an arc shape, and the gap changes smoothly, and the change in the leakage magnetic flux at the ends is smaller than in the embodiment. FIG. 3 shows a third embodiment in which a bobbin 3 is provided to more securely fix the coils 2 and 2 in the axial direction.
A projection 31a having a triangular pyramid shape adapted to the shape of the coil 2;
31b is provided in the axial direction so that the bottom between the two cones has a width W1 in a ring shape, and the coil 2 is wound directly around the bobbin 3 between the two cones so as to have the shape of the embodiment. FIG. 4 shows a fourth embodiment, in which spacers 32a and 32b having a ring-shaped or trapezoidal cross section are provided on the bobbin 3 according to the shape of the coil 2 with a width W1.
The coil 2 is wound directly around the bobbin 3 as in the third embodiment. FIG. 5 shows a fifth embodiment, in which a spacer 34 having a concave groove 33a conforming to the end shape of the embodiment and the second embodiment is provided.
An annular spacer 34b provided with a knock on the outer diameter side of the coil 2 is fitted to the outer diameter side of the bobbin 3 so as to be sandwiched from both ends of the coil 2 formed in advance. When an exciting current is applied to the coil 2, the magnetic field generated by the coil and the field generated by the permanent magnet interlink, and a thrust is generated on either side. At this time, since the leakage magnetic flux (vertical direction) at the end in the axial direction is small, the magnetic force in the vertical direction is small, and the side force is reduced. Further, even if a problem occurs during assembly or misalignment occurs during use, the operation is the same. As described above, according to the present invention, the side force can be reduced, and pitching hardly occurs.

[Brief description of the drawings] FIG. 1 is a sectional view showing an embodiment of the present invention. FIG. 2 is a sectional view of a coil showing a second embodiment of the present invention. FIG. 3 is a sectional view of a bobbin showing a third embodiment of the present invention. FIG. 4 is a sectional view of a bobbin showing a fourth embodiment of the present invention. FIG. 5 is a sectional view of a bobbin showing a fifth embodiment of the present invention. [Explanation of symbols] 1 York 11 Outside yoke 12 side yoke 13 Central yoke 14, 15 permanent magnet 2 coils 3 bobbins 31a, 31b protrusion 32a, 32b, 34a, 34b Spacer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noriaki Iwabuchi 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Inside Yaskawa Electric Co., Ltd. 4-98876 (JP, U) JP-A 1-150474 (JP, U) Special Table 4-500 300 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 33/18

Claims (1)

(57) [Claims] [Claim 1] A pair of flat outer yaws facing each other via a space
And a central support provided axially inside the pair of outer yokes.
Magnetic field between the pair of outer yokes and the central yoke.
A plurality of adjacently arranged opposing poles with alternating poles
A permanent magnet, and a pair of coils disposed between the permanent magnets;
Inner and outer surfaces of axially outer ends of the pair of coils
Voice coil type linear motor with chamfer
Between the permanent magnets and at both ends in the axial direction
A chamfer is provided on the outer end of the coil, and the inner diameter of the coil or
A bobbin made of insulating material is fitted to the outer diameter, and the bobbin is
The coil fitting part has a locking part according to the coil shape
A voice coil type linear motor characterized in that: