JP2020054120A - Moving-coil type voice coil motor - Google Patents

Abstract

To provide a moving-coil type voice coil motor which has a reduced diameter, has an increased cooling efficiency of a coil part, and prevents deterioration in performance of a magnetic circuit due to heating of the coil.SOLUTION: A moving-coil type voice coil motor comprises: a cylindrical pole piece disposed with a gap part provided around a center yoke; a permanent magnet connected to an external peripheral part and an end part of the pole piece; and a side yoke, a bottom yoke, and a top yoke which magnetically couple the permanent magnet and the center yoke. The moving-coil type voice coil motor is characterized in that each of the top yoke and the bottom yoke has an air intake port for cooling the coil, part of the permanent magnet connected to the end part of the pole piece is removed, and a through hole connected to the air inlet port and opened into the gap part is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a moving coil type voice coil motor having a small diameter and improved cooling efficiency.

  A large moving coil type voice coil motor (hereinafter, also simply referred to as "voice coil motor" or "VCM") used for a shaker or the like is controlled using a large current, and the magnitude and control of the control current are controlled. The eddy current generated in the magnetic circuit used in the VCM increases in proportion to the frequency. The generation of a large eddy current not only affects the controllability, but also heats the magnetic circuit due to the heat generated by the eddy current, causing the magnetic circuit to deteriorate in performance. Is being considered.

  Heat generated by the eddy current generated in the magnetic circuit and heat generated by the coil (copper loss) can be removed by installing a fan in the magnetic circuit and air cooling, or by circulating cooling water around the coil and removing it by water cooling The way to do it is generally done.

  In the air cooling method, measures are taken to secure the air volume and air path, such as by increasing the gap between the magnetic gaps where the coils are arranged.However, if the magnetic gap is increased, the performance of the magnetic circuit will be degraded. Resulting in. Therefore, countermeasures such as using a fan having a large static pressure performance to reduce the magnetic air gap as much as possible and increase the flow rate of the cooling air are taken.

  Japanese Patent Application Laid-Open No. 2014-74612 (Patent Document 1) discloses a magnetic path member using a permanent magnet, a movable section having a drive coil inserted into a gap of the magnetic path member, and cooling the magnet and the drive coil. Discloses a permanent magnet type vibration generator equipped with a cooling blower.By controlling the number of rotations of the cooling blower based on the temperature of the magnet and the drive coil, the vibration generator can be cooled efficiently. , The specified vibration capability can be maintained. However, in order to generate a high magnetic field, the vibration generator described in Patent Document 1 has to increase the length of the permanent magnet in the magnetization direction, or use a magnet having a strong magnetic force, and further increase the thickness of the yoke. Therefore, there is a problem that the size of the apparatus is inevitably increased, and the heat generated by the vibration generator is increased, so that sufficient cooling cannot be performed.

  Japanese Patent Application Laid-Open No. 52-131109 (Patent Document 2) discloses that at least one magnet is arranged at each end of a ring-shaped pole piece, and another magnet is arranged around the outer periphery of the ring-shaped pole piece. A magnetic circuit for a linear actuator is disclosed in which a center pole is opposed to the center pole and a yoke joined to each magnet is connected to the center pole. By employing such a magnetic circuit, it becomes possible to obtain a high magnetic field with a smaller diameter. However, in the magnetic circuit described in Reference 2, since the coil must be located at the center of the length of the magnetic circuit, the coil is not sufficiently cooled, causing a rise in the temperature of the magnetic circuit, resulting in reduced performance. Problem.

JP 2014-74612 A JP-A-52-131109

  Accordingly, an object of the present invention is to provide a moving coil type voice coil motor in which the diameter is reduced, the cooling efficiency of the coil portion is increased, and the performance of the magnetic circuit is prevented from deteriorating due to the heating of the coil.

  As a result of intensive research in view of the above objects, the present inventors have found that a cylindrical pole piece arranged with a gap around a center yoke, a permanent magnet connected to the outer peripheral portion and an end of the pole piece, In a movable coil type voice coil motor including a side yoke, a bottom yoke, and a top yoke that magnetically couples these permanent magnets and a center yoke, an air intake port for cooling the coil is provided in the top yoke and the bottom yoke. In addition, by removing a part of the permanent magnet connected to the end of the pole piece and providing a through hole connected to the air intake and opening in the gap, the diameter of the moving coil type voice coil motor can be reduced. At the same time, they found that high cooling efficiency can be exhibited, and arrived at the present invention.

That is, the moving coil type voice coil motor of the present invention,
A cylindrical center yoke,
A plurality of pole pieces arranged in a cylindrical shape by providing a gap portion facing the outer peripheral surface of the center yoke,
Outer peripheral portions of the plurality of pole pieces, a plurality of first permanent magnets, a plurality of second permanent magnets, and a plurality of third permanent magnets arranged in a cylindrical shape at the axial upper and lower ends, respectively,
A cylindrical side yoke connected to the outer periphery of the plurality of first permanent magnets;
A top yoke that magnetically couples the plurality of second permanent magnets and the side yoke at an upper end in the axial direction;
A bottom yoke that magnetically couples the center yoke, the plurality of third permanent magnets, and the side yoke at an axial lower end;
Having a coil disposed in the gap so as to be movable in the axial direction,
In the moving coil type voice coil motor, wherein the first permanent magnet, the second permanent magnet and the third permanent magnet have the same magnetic pole on the side facing the pole piece,
The top yoke and the bottom yoke each have at least one air intake for cooling a coil, a part of a plurality of second permanent magnets arranged in a cylindrical shape, and a plurality of third permanent magnets. A part of the magnet is removed, and a through-hole connected to the air intake and opening in the gap is provided.

  It is preferable that a non-magnetic conductive ring is fixed to an outer peripheral surface of the center yoke and an inner peripheral surface of the plurality of pole pieces so as to face each other.

  It is preferable that the air intake port and the through holes connected to the air intake port are provided in the top yoke and the bottom yoke at three to four places at equal intervals in a circumferential direction, respectively.

  It is preferable that a circumferential position of the air intake port provided in the top yoke is different from a circumferential position of the air intake port provided in the bottom yoke.

  It is preferable that the air intake port and the through hole are made of a material having a high thermal conductivity, and a heat sink member connected to the air intake port and exposed at the top yoke upper part and / or the bottom yoke lower part is provided. .

  The moving coil type voice coil motor of the present invention has a small diameter, sufficiently increases the cooling efficiency of the coil, and can prevent the performance of the magnetic circuit from deteriorating. It can exhibit performance comparable to coil motors.

  In the moving coil type voice coil motor described in the cited document 1, a copper ring (a non-magnetic conductive ring) is disposed immediately above the permanent magnet, and the heat generated by the coil is transmitted to the permanent magnet as it is, so that the permanent magnet is easily formed. Therefore, the temperature of the permanent magnet is greatly increased, thereby deteriorating the magnetic properties. However, in the moving coil type voice coil motor of the present invention, the air volume of the cooling air is increased, and the copper ring is disposed via the pole piece (magnetic material) disposed immediately above the permanent magnet. Are hardly heated, and a decrease in magnetic characteristics is prevented.

  Further, by configuring the air intake port with a material having a high heat transfer coefficient, it becomes possible to release the heat of the pole piece to the outside of the magnetic circuit. This makes it difficult to cause a rapid rise in the temperature of the permanent magnet, so that a decrease in performance can be reduced.

  Further, by installing a radiation fin or the like outside the air intake port, the temperature rise can be further suppressed.

  Further, when the copper ring is disposed immediately above the permanent magnet as in the moving coil type voice coil motor described in Patent Document 1, the copper ring can be fixed to the permanent magnet only by a method such as an adhesive. However, the reliability of the copper ring fixing portion cannot be improved. However, in the moving coil type voice coil motor of the present invention, since the copper ring is arranged on the front surface of the pole piece, it can be fixed by a method such as welding, and the reliability of the copper ring fixing portion is improved.

It is a front view showing an example of a moving coil type voice coil motor of the present invention. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 2 is a sectional view taken along line BB of FIG. FIG. 2 is a sectional view taken along line CC of FIG. FIG. 3 is a sectional view taken along line DD of FIG. 2 (a). FIG. 3 is a sectional view taken along line EE of FIG. 2 (b). FIG. 3 is a sectional view taken along line FF of FIG. 2 (a). It is a front view which shows another example of the moving coil type voice coil motor of this invention. FIG. 5 is a sectional view taken along line GG of FIG. 4 (a).

[1] Moving Coil Type Voice Coil Motor FIGS. 1, 2 (a), 2 (b) and 2 (c) show an example of a moving coil type voice coil motor 1 of the present invention. 1 is a front view, FIG. 2 (a) is a sectional view taken along line AA of FIG. 1, FIG. 2 (b) is a sectional view taken along line BB of FIG. 1, and FIG. 2 (c) is a sectional view taken along line CC of FIG. The moving coil type voice coil motor 1 of the present invention,
A cylindrical center yoke 11,
A plurality of pole pieces 30 arranged in a cylindrical shape by providing a void portion 20 facing the outer peripheral surface 11a of the center yoke 11,
The plurality of first permanent magnets 41, the plurality of second permanent magnets 42, and the plurality of third permanent magnets, each of which is cylindrically disposed on the outer peripheral portion, the axial upper end portion, and the lower end portion of the plurality of pole pieces 30, respectively. 43,
A cylindrical side yoke 12 connected to the outer periphery of the plurality of first permanent magnets 41;
The plurality of second permanent magnets 42, and the top yoke 13 that magnetically couples the side yoke 12 at the upper end in the axial direction,
The center yoke 11, the plurality of third permanent magnets 43, and a bottom yoke 14 that magnetically couples the side yoke 12 at an axial lower end portion,
Having a coil 50 disposed in the gap so as to be movable in the axial direction,
The first permanent magnet 41, the second permanent magnet 42, and the third permanent magnet 43 have the same magnetic pole (N pole in the drawing) on the side facing the pole piece 30,
The top yoke 13 and the bottom yoke 14 each have at least one air intake port 61, 62 for coil cooling, and a part of the plurality of second permanent magnets 42 arranged in a cylindrical shape, and A part of the plurality of third permanent magnets 43 is removed, and through holes 71 and 72 connected to the air intake ports 61 and 62 and opened to the gap 20 are provided.

  The portion surrounded by the first permanent magnet 41, the second permanent magnet 42, the top yoke 13, and the side yoke 12 is preferably filled with a non-magnetic spacer 91. Further, it is preferable that a portion surrounded by the first permanent magnet 41, the third permanent magnet 43, the bottom yoke 14, and the side yoke 12 is filled with a non-magnetic spacer 92. The non-magnetic spacers 91 and 92 are connected to the air intake ports 61 and 62 provided in the top yoke 13 and the bottom yoke 14, and are provided with through-holes 71a and 72a. Non-magnetic spacers 91b and 92b having through holes 71b and 72b are arranged on the inner peripheral side adjacent thereto.

  With such a configuration, for example, the air that has entered the movable coil type voice coil motor 1 from the air intake port 61 passes through the through-hole 71a and the through-hole 71b to the gap 20, and the coil 50 and the non-magnetic Are cooled, and are discharged from the air intake port 62 through the through holes 72b and 72a. Of course, the flow of air may be reversed. The movable coil type voice coil motor 1 preferably includes a blower (not shown) for supplying cooling air to the air intake port 61 or the air intake port 62.

(1) Basic Configuration FIG. 3 (a) shows a cross-sectional view along the line DD in FIG. 2 (a). The basic configuration of the moving coil type voice coil motor of the present invention includes a columnar center yoke 11, and a plurality of pole pieces 30 which are arranged in a cylindrical shape with a void portion facing the outer peripheral surface of the center yoke 11. A plurality of first permanent magnets 41 (main magnets) arranged in a cylindrical shape on the outer peripheral portion of the plurality of pole pieces 30; and a cylindrical side yoke 12 connected to the plurality of first outer peripheral portions. Further, as shown in FIG.2 (c), in addition to the plurality of first permanent magnets 41, each of the plurality of pole pieces 30 is disposed in a cylindrical shape at an upper end portion and a lower end portion in the axial direction, respectively. It has a plurality of second permanent magnets 42 (auxiliary magnets) and a plurality of third permanent magnets 43 (auxiliary magnets), and has a center yoke 11, side yokes 12, and a plurality of first to third permanent magnets. Is magnetically connected by top yoke 13 and bottom yoke 14 to form a magnetic circuit That.

  The first permanent magnet 41 is a main magnet, for example, is made of a ferrite-based sintered magnet, and is configured to have radial anisotropy as a whole when arranged in a cylindrical shape. The pole piece 30 is magnetized so that the side facing the pole piece 30 becomes the N pole and the side yoke 12 side becomes the S pole. The second permanent magnet 41 and the third permanent magnet 43 are auxiliary magnets and are made of, for example, a ferrite-based sintered magnet, and the side facing the pole piece 30 faces the pole piece 30 of the first permanent magnet 41. It is magnetized to have the same magnetic pole as the magnetic pole on the side. In the figure, the side facing the pole piece 30 is the N pole, and the side facing the top yoke 13 or the bottom yoke 14 is the S pole.

  The pole piece 30 exhibits a magnetic shunting effect (increases the uniformity of the magnetic field) and a base for fixing the plurality of first permanent magnets, the plurality of second permanent magnets, and the plurality of third permanent magnets. It can be. The thickness of the pole piece 30 is not particularly limited, but is preferably 5 mm or more. It is preferable to use a known magnetic material (soft magnetic material) for the pole piece 30, and it is particularly preferable to use a magnetic steel material.

  The center yoke 11, the side yoke 12, the top yoke 13, and the bottom yoke 14 are formed of a ferromagnetic material such as soft iron or steel, and the coil 50 is formed of an inner peripheral surface of the pole piece 30 and the center yoke 11 facing the inner surface. Is wound in a direction interlinking with the magnetic flux between the outer peripheral surface of the magnetic head and the magnetic head. When an alternating current is supplied to the coil 50, the coil 50 vibrates up and down in a magnetic field between the inner peripheral surface of the pole piece 30 and the outer peripheral surface of the center yoke 11 opposed thereto. By arranging a device under test (not shown) on a movable table (not shown) connected to the coil 50, a vibration test of the device under test can be performed.

  It is preferable that nonmagnetic conductive rings 81 and 82 are fixed to the outer peripheral surface 11a of the center yoke 11 and the inner peripheral surfaces of the plurality of pole pieces 30 opposed thereto. These non-magnetic conductive rings 81 and 82 exhibit an effect of reducing eddy current, and are provided as necessary. The nonmagnetic conductive rings 81 and 82 are preferably made of, for example, a copper plate.

(2) Air intake port and through hole As described above, in the moving coil type voice coil motor 1 of the present invention, air intake ports 61 and 62 provided in the top yoke 13 and the bottom yoke 14, Since the top yoke 13 and the bottom yoke 14 each have at least one through hole 71, 72 for connecting and sending cooling air to the gap 20, the coil 50 and the nonmagnetic conductive rings 81, 82 are high. It can be cooled with efficiency.

  It is preferable that a plurality of air intake ports 61 provided to open in the top yoke 13 are provided in the circumferential direction. The moving coil type voice coil motor shown in FIGS. 1, 2 (a), 2 (b) and 2 (c) is provided on the top yoke 13 as shown in FIGS. 1 and 3 (b). Although the air intake port 61 has a configuration provided at four locations every 90 ° in the circumferential direction, the number of the air intake ports 61 may be three or less, or may be five or more. The air intake ports 61 are preferably provided at two to four locations in the circumferential direction, and more preferably at three to four locations. The circumferential intervals are preferably equal intervals (equal angles). Further, an air intake port 62 provided to open to the bottom yoke 14 is also configured in the same manner as the air intake port 61 provided to open to the top yoke 13, as shown in FIG. Is preferred. The air intake port 61 of the top yoke 13 and the air intake port 62 of the bottom yoke 14 may have the same or different numbers in the circumferential direction, but are preferably provided in the same number and at the same interval.

  The air intake port 61 of the top yoke 13 and the air intake port 62 of the bottom yoke 14 may be provided so that the positions in the circumferential direction coincide with each other. In order to allow the coil 50 and the non-magnetic conductive rings 81 and 82 to flow in the same direction, and to increase the cooling efficiency of the non-magnetic conductive rings 81 and 82, it is preferable to displace them in the circumferential direction. That is, it is preferable that the air intake port 61 of the top yoke 13 and the air intake port 62 of the bottom yoke 14 are provided so as to be out of phase. For example, in the examples shown in FIGS. 1, 2 (a), 2 (b), and 2 (c), the number of the air intake ports 61, 62 in the circumferential direction is four (each 90 ° in the circumferential direction). It is preferable that the air intake 61 and the air intake 62 are arranged so as to be shifted by 45 °. That is, when the n air intake ports 61.62 are arranged at equal intervals, the air intake ports 61 and the air intake ports 62 are provided at every (360 / n) ° in the circumferential direction. 180 / n) °.

  The movable coil type voice coil motor 1 may be provided with an auxiliary air intake 63 at the bottom yoke 14 at the bottom of the gap 20 in order to send cooling air into the gap 20.

(3) Heat sink member The air intake port 61 and the through hole 71 are made of a high heat conductive material having a high thermal conductivity, are connected to the air intake port 61 and the through hole 71, and are exposed on the top yoke 13 above the heat sink member 100. May be provided. That is, as shown in FIGS. 4 (a) and 4 (b), for example, the non-magnetic spacers 91a and 91b forming the through-hole 71 are formed of a high heat conductive material, and the air provided on the top yoke 13 is formed. It is preferable that the intake port 61 is formed of the high heat conductive member 101, and the heat sink member 100 connected to the high heat conductive member 101 is disposed above the top yoke 13. Similarly, the non-magnetic spacers 92a and 92b forming the through hole 72 are formed of a high heat conductive material, and the air intake port 62 provided in the bottom yoke 14 is formed of a high heat conductive member. The heat sink member connected to the member may be arranged so as to be exposed below the bottom yoke 14.

1 Moving coil type voice coil motor
11 ・ ・ ・ Center yoke
11a ・ ・ ・ Outer peripheral surface
12 ・ ・ ・ Side yoke
13 ・ ・ ・ Top yoke
14 ・ ・ ・ Bottom yoke
20 ・ ・ ・ Void
30 ・ ・ ・ Pole piece
41 ・ ・ ・ First permanent magnet
42 ・ ・ ・ Second permanent magnet
43 ・ ・ ・ Third permanent magnet
50 ・ ・ ・ coil
61,62 ・ ・ ・ Air intake
63 ・ ・ ・ Auxiliary air intake
71,72 ・ ・ ・ through hole
71a, 72a ・ ・ ・ Through hole
71b, 72b ・ ・ ・ Through hole
81,82 ・ ・ ・ Non-magnetic conductive ring
91,92 ・ ・ ・ Non-magnetic spacer
91a, 92a ・ ・ ・ Non-magnetic spacer
91b, 92b ・ ・ ・ Non-magnetic spacer
100 ・ ・ ・ Heat sink member
101 ・ ・ ・ High thermal conductive material

Claims (5)

A cylindrical center yoke,
A plurality of pole pieces arranged in a cylindrical shape by providing a gap portion facing the outer peripheral surface of the center yoke,
Outer peripheral portions of the plurality of pole pieces, a plurality of first permanent magnets arranged in a cylindrical shape at an axial upper end portion and a lower end portion, a plurality of second permanent magnets and a plurality of third permanent magnets,
A cylindrical side yoke connected to the outer periphery of the plurality of first permanent magnets;
A top yoke that magnetically couples the plurality of second permanent magnets and the side yoke at an upper end in the axial direction;
A bottom yoke that magnetically couples the center yoke, the plurality of third permanent magnets, and the side yoke at an axial lower end;
Having a coil disposed in the gap so as to be movable in the axial direction,
In the moving coil type voice coil motor, wherein the first permanent magnet, the second permanent magnet and the third permanent magnet have the same magnetic pole on the side facing the pole piece,
The top yoke and the bottom yoke each have at least one air intake for cooling a coil, a part of a plurality of second permanent magnets arranged in a cylindrical shape, and a plurality of third permanent magnets. A moving coil type voice coil motor, wherein a part of a magnet is removed, and a through hole is provided which is connected to the air intake port and opens to the gap. In the moving coil type voice coil motor according to claim 1,
A moving coil type voice coil motor, wherein a non-magnetic conductive ring is fixed to an outer peripheral surface of the center yoke and an inner peripheral surface of the plurality of pole pieces so as to face each other. In the moving coil type voice coil motor according to claim 1 or 2,
A moving coil type voice coil motor, wherein the air intake port and the through hole connected thereto are provided at three to four places at equal intervals in a circumferential direction on the top yoke and the bottom yoke, respectively. The moving coil type voice coil motor according to any one of claims 1 to 3,
A moving coil type voice coil motor, wherein a circumferential position of the air intake provided in the top yoke is different from a circumferential position of the air intake provided in the bottom yoke. The moving coil type voice coil motor according to any one of claims 1 to 4,
The air intake port and the through hole are made of a material having a high thermal conductivity, and a heat sink member connected to the air intake port and exposed at an upper portion of the top yoke and / or a lower portion of the bottom yoke is provided. Moving coil type voice coil motor.

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