JP6750373B2 - Moving coil type voice coil motor - Google Patents

Description

The present invention relates to a moving coil type voice coil motor capable of reducing an eddy current and realizing a magnet shape that is easy to manufacture.

A large moving coil type voice coil motor (also called VCM) used for an exciter is controlled by using a large current, and is used for VCM in proportion to the magnitude of the control current and the control frequency. The eddy current generated in the existing magnetic circuit also increases. When a large eddy current is generated, not only the controllability is affected, but also the magnetic circuit is heated by the heat generated by the eddy current, causing the performance of the magnetic circuit to deteriorate. Therefore, various cooling methods for cooling the magnetic circuit are provided. Is being considered.

The heat generated by the eddy current generated in the magnetic circuit and the heat generated by the coil (copper loss) are generally removed by air cooling with a fan installed in the magnetic circuit. Further, in the VCM, in order to improve the responsiveness, a copper member called a short ring is arranged on the surface of the magnetic body of the magnetic circuit to suppress the generation of eddy currents. However, in a VCM used in a large exciter that requires a large thrust, the magnetic circuit also increases in proportion to the generated thrust, so this short ring also has a large diameter. Since the short ring is manufactured from a cylindrical copper material as a thin ring-shaped integral part, the manufacturing cost increases with the increase in size of the VMC.

Japanese Unexamined Patent Publication No. 2014-74612 (Patent Document 1) has a cylindrical yoke member, a disk-shaped bottom plate, and a cylindrical center yoke, and the cylindrical yoke member and the cylindrical center yoke are respectively One end is joined to a disk-shaped bottom plate, and a ring-shaped magnet magnetized in the radial direction is arranged on the side of the cylindrical yoke member facing the center yoke, and a coil is placed between the magnet and the center yoke. , A moving coil type voice coil motor is disclosed which drives the coil in the axial direction by the interaction of the current flowing in the coil and the magnetic field of the magnet. On the outer peripheral surface of the center yoke and the inner peripheral surface of the ring-shaped magnet of the moving coil type voice coil motor described in Patent Document 1, a copper short ring for improving the rising characteristics of the coil is closely arranged.

Here, the short ring is a thin plate made of a metal material having high conductivity such as copper in the vicinity of the coil so that the eddy current due to the change of the magnetic field generated by the coil is not generated on the yoke or the magnet surface. It is attached to the surface. In order to secure the mechanical strength of a thin plate such as copper, the copper ring is arranged along the outer peripheral surface of the center yoke and the inner peripheral surface of the ring-shaped magnet. Therefore, it is necessary to grind the inner peripheral surface of the ring magnet into an arc shape as shown in FIG. However, grinding the magnet into an arc shape requires the production of a dedicated processing grindstone, resulting in an increase in cost. Further, the short ring described in Patent Document 1 has no effect of preventing eddy currents generated on the upper and lower surfaces of the permanent magnet, and further improvement is desired.

JP 2014-74612 JP

Therefore, the object of the present invention is to reduce the manufacturing cost of the permanent magnet even when the short ring for preventing the generation of the eddy current is provided, and further to suppress the eddy current generated on the upper and lower surfaces of the permanent magnet. (EN) Provided is a movable coil type voice coil motor which is prevented.

As a result of earnest research in view of the above-mentioned object, the present inventors have proposed a plurality of moving coil type voice coil motors having a center yoke and a permanent magnet arranged in a cylindrical shape facing the outer peripheral surface of the center yoke. The permanent magnets are arranged in a cylindrical shape, and a non-magnetic conductive plate is provided so as to cover the magnetic pole surfaces, the upper surface, and the lower surface of each permanent magnet, thereby processing the magnetic pole surface facing the center yoke into an arc shape. The inventors have found that it is not necessary to do so and can prevent eddy currents generated on the upper and lower surfaces of the permanent magnet, and have conceived the present invention.

That is, the moving coil type voice coil motor of the present invention is
A cylindrical or cylindrical center yoke,
A plurality of cylindrically arranged permanent magnets facing each other on the outer peripheral surface of the center yoke so as to apply a magnetic field in the radial direction of the center yoke;
A cylindrical side yoke arranged on the outer periphery of the plurality of permanent magnets and fixing the plurality of permanent magnets,
A bottom yoke that magnetically couples an axial end portion of the center yoke to the side yoke,
A coil disposed in the gap so as to be movable in the axial direction,
A non-magnetic conductive ring provided on the outer peripheral surface of the center yoke facing the magnetic pole surfaces of the plurality of permanent magnets;
Each of the plurality of permanent magnets has a magnetic pole surface facing the center yoke, and a non-magnetic conductive plate provided so as to cover an upper surface and a lower surface.

The permanent magnet preferably has a trapezoidal shape or a rectangular shape when viewed in the axial direction.

The permanent magnet preferably comprises a plurality of parts divided in the radial direction.

The non-magnetic conductive plate is preferably provided so as to cover the side yoke.

The non-magnetic conductive plates provided on each of the permanent magnets are preferably electrically connected by a conductive member.

It is preferable that the inner peripheral surface of the side yoke has a polygonal shape corresponding to the number of the plurality of permanent magnets.

It is preferable that the permanent magnet is fixed to the side yoke via a mounting yoke.

The mounting yoke preferably has an arcuate outer peripheral surface.

In the moving coil type voice coil motor of the present invention, the short ring, which has been conventionally manufactured integrally, has a divided structure, so that the manufacturing cost of the short ring can be reduced and the optimum short ring can be easily designed. become.

Further, the shape of the permanent magnet used in the magnetic circuit has conventionally been required to be a shape (arc shape) along the short ring in order to secure the fixing strength of the short ring. Since it is not necessary to make a part of the shape of the permanent magnet into an arc shape, it is possible to manufacture it in a rectangular shape, and because the grindstone necessary for manufacturing the arc shape part of the permanent magnet is not necessary, an inexpensive permanent magnet The magnetic circuit can be configured with. As a result, it is possible to significantly reduce the manufacturing cost of the moving coil type voice coil motor.

The divided short ring has a shape that matches the shape of each permanent magnet, and can be fixed by, for example, screwing on the side surface of the yoke that fixes the permanent magnet. With this configuration, it is possible to suppress the generation of eddy currents that occur when the coil magnetic field passes through the upper and lower surfaces of the permanent magnet, which was not possible with the conventional configuration, and it is possible to suppress heat generation in the magnetic circuit. Become.

It is the (a) front view and the (b) AA cut end view which show an example of the moving coil type voice coil motor of this invention. It is (a) front view and (b) BB cut end view which show another example of the moving coil type voice coil motor of this invention. It is (a) front view and (b) CC end view which show another example of the moving coil type voice coil motor of the present invention. FIG. 4A is a front view showing one magnet portion extracted from the moving coil type voice coil motor of FIG. 3, and FIG. It is (a) front view and (b) EE cut end view which show another example of the moving coil type voice coil motor of the present invention. It is (a) front view and (b) FF cut end view which show another example of the moving coil type voice coil motor of this invention. FIG. 7A is a schematic view showing one magnet part of the moving coil type voice coil motor shown in FIG. 5A, and FIG. 6B is a schematic view showing one magnet part of the moving coil type voice coil motor shown in FIG. .. It is a schematic diagram which shows the method of assembling the moving coil type voice coil motor of this invention. FIG. 9A is a front view showing an example of a conventional moving coil type voice coil motor, and FIG.

[1] Moving coil voice coil motor
(1) Conventional moving coil type voice coil motor A conventional moving coil type voice coil motor is shown in FIG. A conventional moving coil type voice coil motor 9 has a cylindrical center yoke 10 and a hollow space 20 facing the outer peripheral surface of the center yoke 10 so as to apply a magnetic field in the radial direction of the center yoke 10. -Shaped permanent magnets 39, a cylindrical side yoke 49 arranged on the outer periphery of the permanent magnets 39 and fixing the permanent magnets 39, and an axial end of the center yoke 10. A bottom yoke 50 magnetically coupled to the side yoke 49, a coil 60 axially movable in the void 20, and a center yoke facing the magnetic pole surfaces 39a of the plurality of permanent magnets 39. A non-magnetic conductive ring 70 is provided on the outer peripheral surface of 10, and a non-magnetic conductive ring 89 is provided on the magnetic pole surface 39a of the plurality of permanent magnets 39 that faces the center yoke 10.

The permanent magnet 39 is preferably made of a rare earth magnet such as a ferrite sintered magnet or a Nd—Fe—B sintered magnet. The plurality of permanent magnets 39 are configured so as to have radial anisotropy as a whole when they are arranged in a cylindrical shape. For example, the side facing the center yoke 10 (the magnetic pole surface 39a side) is an N pole and the side yoke 49. It is magnetized so that the side end face 39d becomes the S pole. The center yoke 10 and the side yokes 49 are made of a ferromagnetic material such as soft iron or steel, and the coil 60 is provided between the magnetic pole surfaces 39a of the plurality of permanent magnets 39 and the outer peripheral surface of the center yoke 10 facing the magnetic pole surfaces 39a. It is wound in the direction that intersects with the magnetic flux of. When an alternating current is supplied to the coil 60, the coil 60 vertically vibrates in the magnetic field between the magnetic pole surfaces 39a of the plurality of permanent magnets 39 and the outer peripheral surface of the center yoke 10 facing the magnetic pole surfaces 39a. By placing a device under test (not shown) on a movable table (not shown) connected to the coil 60, a vibration test of the device under test can be performed.

In order to suppress the generation of eddy currents, the conventional moving coil type voice coil motor 9 has an annular non-magnetic material on the outer peripheral surface of the center yoke 10 and the magnetic pole surface 39a of the permanent magnet 39 that faces the center yoke 10. A conductive ring 70 and a conductive ring 89 are provided. Therefore, the magnetic pole surface 39a of each permanent magnet 39 facing the center yoke 10 is processed into an arc shape. Further, since the plurality of permanent magnets 39 are fixed to the side yoke 49 having an arcuate inner peripheral surface, the side yoke 49 side end surface 39d of each permanent magnet 39 is also processed into an arcuate shape. Grinding the magnetic pole surface 39a and the end surface 39d of the permanent magnet 39 into an arc shape as described above requires the production of a dedicated processing grindstone, which causes an increase in cost. Further, the conventional moving coil type voice coil motor 9 has no effect of reducing the eddy current generated on the upper surface 39b and the lower surface 39c of the permanent magnet 39.

(2) Moving coil type voice coil motor of the present invention
(a) First Embodiment FIG. 1 shows a first embodiment of a moving coil type voice coil motor of the present invention. The moving coil type voice coil motor 1 of the present invention is provided with a cylindrical center yoke 10 and a void portion 20 facing the outer peripheral surface of the center yoke 10 so as to apply a magnetic field in the radial direction of the center yoke 10. A plurality of permanent magnets 30 arranged in a cylindrical shape, cylindrical side yokes 40 arranged on the outer periphery of the plurality of permanent magnets 30 and fixing the plurality of permanent magnets 30, and axial end portions of the center yoke 10. A bottom yoke 50 that magnetically couples the side yoke 40 to the side yoke 40; a coil 60 that is axially movable in the void 20; and a center yoke that faces the magnetic pole surfaces 30a of the plurality of permanent magnets 30. A non-magnetic conductive ring 70 provided on the outer peripheral surface of 10 and each of the plurality of permanent magnets 30 are provided so as to cover the magnetic pole surface 30a, the upper surface 30b, and the lower surface 30c that face the center yoke 10. And a magnetic conductive plate 80.

The moving coil type voice coil motor 1 of the present invention uses a permanent magnet having a different shape, a non-magnetic conductive plate 80 is used in place of the conductive ring 89, and a side yoke 40 forming a polygonal inner peripheral surface. Other than that, the basic structure is the same as the conventional moving coil type voice coil motor 9.

In the moving coil type voice coil motor 1, 20 trapezoidal permanent magnets 30 are arranged in a cylindrical shape in plan view (as viewed in the axial direction of the moving coil type voice coil motor 1) so as to face the cylindrical center yoke 10. The permanent magnet 30 and the center yoke 10 are magnetically coupled via the side yoke 40 and the bottom yoke 50 to form a magnetic circuit. The magnetic pole (N pole in the figure) on the side of the permanent magnet 30 that faces the center yoke 10 is a flat surface, and the other magnetic pole (S pole in the figure) matches the number of permanent magnets 30 (20 in the example). It is fixed to the side yoke 40 that constitutes the inner peripheral surface of the polygon. The movable coil type voice coil motor 1 shown in FIG. 1 is configured by using the cylindrical center yoke 10, but the center yoke 10 may be cylindrical.

A non-magnetic conductive plate 80 (for example, a copper plate) is attached to the magnetic pole surface 30a, the upper surface 30b, and the lower surface 30c of the permanent magnets 30 that face the center yoke 10. Similar to the short ring of the magnetic circuit used, it has the effect of reducing eddy currents. In each permanent magnet 30, the non-magnetic conductive plate 80 that covers the magnetic pole surface 30a, the upper surface 30b, and the lower surface 30c is preferably integrally formed. In FIG. 1, the non-magnetic conductive plate 80 is provided so as to cover almost the upper end surface of the side yoke 40. Further, the non-magnetic conductive plates 80, 80 respectively provided on the permanent magnet 30 and the permanent magnet 30 adjacent to the permanent magnet 30 are in contact with each other and electrically connected. Since the eddy current tends to flow in the circumferential direction of the moving coil type voice coil motor 1 in a plan view, the non-magnetic conductive plates 80, 80 adjacent to each other are electrically connected to each other so that the eddy current flows in a circular manner. ..

(b) Second Embodiment FIG. 2 shows a second embodiment of the moving coil type voice coil motor of the present invention. The BB cut end view shown in FIG. 2(b) shows a portion where the permanent magnet 31 is present (right side in the figure) and a portion where it is not present (left side in the figure). The moving coil type voice coil motor 2 of the second embodiment uses a rectangular permanent magnet 31 in a plan view instead of the trapezoidal permanent magnet 30 in a plan view, and each of the permanent magnets 31 has a magnetic pole surface 31a (center). The side facing the yoke 10), the non-magnetic conductive plate 81 is provided so as to cover the upper surface 31b and the lower surface 31c, and a conductive wire 81a for electrically connecting each conductive plate 81 is provided. This is similar to the moving coil type voice coil motor 1. In FIG. 2, the non-magnetic conductive plate 81 is provided so as to cover a part of the upper end surface of the side yoke 40.

Similar to the moving coil type voice coil motor 1 of the first embodiment, since the eddy current tends to flow in the circumferential direction of the moving coil type voice coil motor 2 in a plan view, the adjacent non-magnetic conductive plates 81, 81 are connected to each other. It is configured so that an eddy current circulates and flows by conducting with a conducting wire 81a. Since the moving coil type voice coil motor 2 of the second embodiment uses a permanent magnet 31 having a rectangular shape in plan view, it is possible to further reduce the cost. Although described as a conducting wire, a plate-like or rod-like conducting member having conductivity without being restricted by the wire may be formed in an annular shape. It suffices that all the conductive plates that circulate are made conductive by the conductive plates adjacent to each other being conductive.

(c) Third Embodiment FIG. 3 shows a moving coil type voice coil motor according to a third embodiment of the present invention. The moving coil type voice coil motor 3 of the third embodiment uses a permanent magnet 32 having a shape in which a rectangular portion and a trapezoidal portion are combined in a plan view, instead of the trapezoidal permanent magnet 30 in a plan view. A trapezoidal mounting yoke 90 in a plan view is provided between the side yokes 41 for each permanent magnet 32, and each of the permanent magnets 32 has a magnetic pole surface 32a (a side facing the center yoke 10) and an upper surface 32b. The non-magnetic conductive plate 82 is provided so as to cover the lower surface 32c, the upper surface 90a and the lower surface 90b of the mounting yoke 90, and the step portion is provided on the side of the side yoke 40 facing the mounting yoke 90. This is similar to the moving coil type voice coil motor 1. In the third embodiment, the step portion is provided on the side of the side yoke 40 that faces the mounting yoke 90. However, as in the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. A stepped portion may not be provided in the structure. When the stepped portion is not provided, the configuration is as in the fifth embodiment shown in FIG. 6 described later.

FIG. 4 shows a magnet unit 132 used in the moving coil type voice coil motor 3. The magnet unit 132 includes a permanent magnet 32, a mounting yoke 90 coupled to the permanent magnet 32, a magnetic pole surface 32a of the permanent magnet 32 (a side facing the center yoke 10), an upper surface 32b and a lower surface 32c, and a mounting yoke 90. The non-magnetic conductive plate 82 is provided so as to cover the upper surface 90a and the lower surface 90b. The permanent magnet 32 is formed by laminating a permanent magnet 321 having a taper on the side facing the center yoke 10 in a plan view and a rectangular permanent magnet 322. By using the permanent magnet 32 composed of two parts in this way, it becomes possible to construct a magnetic circuit of a moving coil type voice coil motor using a relatively small magnet material.

In addition, by providing a trapezoidal mounting yoke 90 in a plan view between each permanent magnet 32 and the side yoke 41, the magnetic circuit can be easily assembled. It is possible to prevent the permanent magnet 32 from being cracked or chipped due to contact with the yoke 41. The attachment yoke 90 and the permanent magnet 32 may be joined by bonding, but the permanent magnet 32 and the attachment yoke 90 may be provided with a dovetail groove and a dovetail joint, respectively.

(d) Fourth Embodiment FIG. 5 shows a fourth embodiment of the moving coil type voice coil motor of the present invention. The moving coil type voice coil motor 4 of the fourth embodiment is different from that of the third embodiment except that an integrally produced permanent magnet 33 is used instead of the permanent magnet 32 formed by bonding the permanent magnets 321 and 322 together. This is the same as the moving coil type voice coil motor 3.

(e) Fifth Embodiment FIG. 6 shows a fifth embodiment of the moving coil type voice coil motor of the present invention. The movable coil type voice coil motor 5 of the fifth embodiment uses the mounting yoke 91 having an arcuate outer peripheral surface and the side yoke 42 having an inner peripheral surface having a circular cross section, except that the movable yoke of the fourth embodiment is movable. It is similar to the coil type voice coil motor 4.

FIG. 7(a) shows a magnet unit 133 used in the moving coil type voice coil motor 4 of the fourth embodiment, and FIG. 7(b) shows a magnet unit 233 used in the moving coil type voice coil motor 5 of the fifth embodiment. Show. As shown in FIG. 7, the outer peripheral surface of the moving coil type voice coil motor 4 is flat, whereas the outer peripheral surface of the mounting yoke 91 of the moving coil type voice coil motor 5 is arcuate. It was formed in. By thus forming the outer peripheral surface of the mounting yoke 91 in an arc shape, the inner peripheral surface of the side yoke 42 can be formed in a circular cross section, and the cross section of the movable coil type voice coil motor 4 of the fourth embodiment can be increased. The inner peripheral surface of the side yoke 42 can be processed more easily than the side yoke 41 having a square inner peripheral surface.

[2] Assembling process of moving coil type voice coil motor FIG. 8 shows an assembling process of the moving coil type voice coil motor 5 of the fifth embodiment. The magnetized magnet unit 233 shown in FIG. 7(b) is bonded or mechanically fixed to the inner peripheral surface side of the side yoke 42 using an assembly jig (not shown). The magnet unit 233 includes a permanent magnet 33, a mounting yoke 91 coupled to the permanent magnet 33, a magnetic pole surface 33a of the permanent magnet 33 (a side facing the center yoke 10), an upper surface 33b and a lower surface 33c, and an upper surface of the mounting yoke 91. 91a and a nonmagnetic conductive plate 82 provided so as to cover the lower surface 91b. The non-magnetic conductive plate 82 is made of, for example, a copper plate, and may be adhesively fixed to the permanent magnet 33 and the mounting yoke 91 or may be mechanically fixed.

1, 2, 3, 4, 5... Moving coil type voice coil motor
9... Conventional moving coil type voice coil motor
10...Center yoke
20... void
30, 31, 32, 33, 39... Permanent magnet
321, 322... Permanent magnet
30a, 31a, 32a, 33a, 39a... Magnetic pole face
30b, 31b, 32b, 33b, 39b...Top surface
30c, 31c, 32c, 33c, 39c...Bottom surface
40, 41, 42, 49... Side yoke
50...bottom yoke
60... coil
70: Non-magnetic conductive ring
80, 81, 82, 89... Non-magnetic conductive plate
81a...Conductive wire
90, 91...Mounting yoke
90a, 91a...Top
90b, 91b...Bottom surface
132, 133, 233... Magnet unit

Claims (8)

A cylindrical or cylindrical center yoke,
A plurality of cylindrically arranged permanent magnets facing each other on the outer peripheral surface of the center yoke so as to apply a magnetic field in the radial direction of the center yoke;
A cylindrical side yoke arranged on the outer periphery of the plurality of permanent magnets and fixing the plurality of permanent magnets,
A bottom yoke that magnetically couples an axial end portion of the center yoke to the side yoke,
A coil disposed in the gap so as to be movable in the axial direction,
A non-magnetic conductive ring provided on the outer peripheral surface of the center yoke facing the magnetic pole surfaces of the plurality of permanent magnets;
To each of the plurality of permanent magnets, pole faces facing the center yoke, have a non-magnetic conductive plate arranged to cover an upper surface and a lower surface, said non-magnetic conductive plate, electrically by conductive member moving-coil voice coil motors, characterized in that it is connected. The voice coil motor according to claim 1,
A moving coil type voice coil motor, wherein the permanent magnet has a trapezoidal shape when viewed in the axial direction. The voice coil motor according to claim 1,
A movable coil type voice coil motor, wherein the permanent magnet has a rectangular shape when viewed in the axial direction. The voice coil motor according to any one of claims 1 to 3,
A moving coil type voice coil motor, wherein the permanent magnet is composed of a plurality of parts divided in a radial direction. The voice coil motor according to any one of claims 1 to 4,
A moving coil type voice coil motor, wherein the non-magnetic conductive plate is provided so as to cover the side yoke. In the voice coil motor according to any one of claims 1 to 5
A movable coil type voice coil motor, wherein an inner peripheral surface of the side yoke has a polygonal shape corresponding to the number of the plurality of permanent magnets. In the voice coil motor according to any one of claims 1 to 6
A moving coil type voice coil motor, wherein the permanent magnet is fixed to a side yoke via a mounting yoke. The voice coil motor according to claim 7 ,
A moving coil type voice coil motor, wherein the mounting yoke has an arcuate outer peripheral surface.

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