JP7101604B2 - Vibration actuator - Google Patents

Description

The present invention relates to a vibration actuator, and more particularly to a vibration actuator having a small leakage magnetic flux.

Conventionally, as a tactile interface for realizing virtual reality, a method of rotating an eccentric mass with a rotating motor to obtain vibration has been used.
However, the method using a conventional rotary motor has a drawback that the reaction is slow until the eccentric mass starts to rotate and the vibration is obtained as a tactile sensation because the vibration is generated by the inertial force of the eccentric mass, and the reality is impaired. rice field.

Therefore, it is considered to use a voice coil type vibration actuator as an actuator for obtaining a more realistic tactile sensation.
The vibration actuator having a movable magnet type mover is provided inside a metal cylindrical case, an electromagnetic drive unit provided inside the case, and inside the electromagnetic drive unit, and is provided along the vibration axis direction. It has a vibrating actuator (magnet).

Then, in order to support the mover that vibrates (reciprocating motion), the metal shaft provided on the mover is supported by the bearings provided on the two end faces in the vibration axis direction of the case along the vibration axis direction. Structure is used.
Further, a pair of spiral springs are provided so as to sandwich the mover along the vibration axis so that the mover is positioned at the neutral position of the reciprocating motion. One end of the pair of spiral springs engages with the case and the other end engages with the mover, so that the pair of spiral springs can be flexed along the vibration axis (see, for example, Reference 1).

Japanese Patent No. 5342516

However, the vibration actuator having the above configuration has the following problems.
(1) In order to obtain a large vibration at a low frequency, it is necessary to increase the weight of the mover. And since we want to vibrate the heavy mover linearly (reciprocating motion), a large driving force is required.

In particular, in the above-mentioned voice coil type vibration actuator, since the mover is supported by the shaft and the bearing, the resistance when the mover starts to vibrate (mainly the static friction force generated between the shaft and the bearing). Is large and requires a large driving force.
In order to obtain a large vibration force, a large driving force is required, the coil of the electromagnetic drive unit and the magnet of the mover become large, and the vibration actuator becomes heavy and large.

(2) If the case is made of a magnetic material (metal) having a high magnetic permeability in order to prevent leakage of magnetic flux generated by the coil of the electromagnetic drive unit and the magnet of the mover, the vibration actuator becomes heavy.

(3) In the above-mentioned voice coil type vibration actuator, the end portion of the metal shaft in the vibration axis direction protrudes to the outside of the case, and the magnetic flux from the protruding end portion of the shaft leaks. That is, the leakage magnetic flux in the vibration axis direction is large.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vibration actuator that is compact, lightweight, and can reduce leakage magnetic flux.

The vibration actuator of the invention according to claim 1 that solves the problem is
A case made of a tubular non-magnetic material and
A tubular electromagnetic drive unit provided inside the case,
A mover provided on the inside in the radial direction of the electromagnetic drive unit and supported so as to vibrate along the vibration axis, and a mover.
A pair of leaf springs that support one end and the other end of the mover in the vibration axis direction, respectively.
Have,
The mover is
With a magnet
A pair of pole pieces made of a soft magnetic material sandwiching the magnet from both sides along the vibration axis,
A pair of weights made of non-magnetic material sandwiching the pair of pole pieces from both sides along the vibration axis,
Have,
The electromagnetic drive unit
A pair of coils arranged at intervals along the vibration axis and each formed in a cylindrical shape,
A cylindrical yoke made of a soft magnetic material, which is arranged radially outside the pair of coils and is formed so as to project outward in the vibration axis direction from the pair of coils.
Have,
In the vibration axis direction, the height of the yoke is larger than the height from one end to the other end of the pair of pole pieces, and is larger than the height from one end to the other end of the pair of weights. It is characterized by being small.
Further, in the vibration actuator, the cross-sectional area of the weight in the plane direction orthogonal to the vibration axis may be gradually narrowed toward the end of the tubular case.
Further, in the vibration actuator, the height of each weight of the pair of weights may be larger than the height of each pole piece of the pair of pole pieces in the vibration axis direction.
Further, the case of the vibration actuator may be made of resin.

Other features of the invention will become more apparent from the embodiments and accompanying drawings for carrying out the invention described below.

By implementing the present invention, since the weight of the electromagnetic drive unit made of non-magnetic material functions as a space securing member, the distance from the electromagnetic drive unit that emits magnetic flux to the outer surface (outer surface) of the case made of tubular non-magnetic material. It is possible to reduce the magnetic flux leakage even if a case made of a light non-magnetic material is used without using a special heavy metallic magnetic shielding case, so that the vibration actuator can be made smaller and lighter.

Further, since the conventional mover does not have a metal shaft protruding to the outside of the case, the leakage magnetic flux in the vibration axis direction is also reduced.
Other effects of the invention will become even more apparent from the embodiments and accompanying drawings for carrying out the invention described below.

It is an exploded perspective view explaining the embodiment of the vibration actuator of this invention. It is a top view when FIG. 1 is assembled. It is a front view of FIG. It is a rear view of FIG. It is a bottom view of FIG. It is a left side view of FIG. It is a right side view of FIG. FIG. 5 is a cross-sectional view taken along the line VIII-VIII of FIG. It is a figure explaining the operation of the vibration actuator shown in FIG. It is a figure which shows the magnetic flux density distribution of the leakage magnetic flux of a vibrating actuator. FIG. 10 is a diagram showing the relationship between the distance from the vibration actuator in the Z-axis direction of FIG. 10 and the leakage magnetic flux. FIG. 10 is a diagram showing the relationship between the distance from the vibration actuator in the X-axis direction and the leakage magnetic flux in FIG.

An embodiment will be described with reference to the drawings. 1 is an exploded perspective view illustrating an embodiment of the vibration actuator of the present invention, FIG. 2 is a plan view when FIG. 1 is assembled, FIG. 3 is a front view of FIG. 2, and FIG. 4 is a rear view of FIG. 2. 5 is a bottom view of FIG. 2, FIG. 6 is a left side view of FIG. 3, FIG. 7 is a right side view of FIG. 3, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 5, and FIG. 9 is shown in FIG. It is a figure explaining the operation of a vibration actuator.

(Constitution)
The overall configuration of the vibration actuator 2 of the embodiment will be described with reference to FIGS. 1 to 8.
Inside the case 1 which is cylindrical and made of resin such as ABS with openings at both ends, an electromagnetic drive unit 10 including a cylindrical yoke 11 and a coil 21 is provided.

The yoke 11 is provided on the inner peripheral surface of the case 1 and is made of a cylindrical soft magnetic material having a large magnetic permeability. The inner peripheral surface of the yoke 11 is electrically insulated from the yoke 11 and is along the vibration axis O (the axis of the cylindrical case 1 and along the vibration direction of the mover 111 described later). Two coils 21 are attached. That is, the yoke 11 is arranged outside the pair of coils 21 in the radial direction.

A cylindrical first cover case 31 made of a resin such as ABS is arranged on one end surface of the case 1 on the opening side. A cylindrical second cover case 41 made of a resin such as ABS is arranged on the other end surface of the case 1 on the opening side.

A first suspension unit (leaf spring) 153 is arranged on the end surface of the first cover case 31 on the opening side opposite to the case 1. The first suspension unit 153 is formed by processing a thin plate of stainless steel (SUS304 in this embodiment), and has a first suspension 51 and a first suspension, which are leaf springs whose central portion is flexible along the vibration axis O. It is composed of a first elastic material 150 provided in 51.

A second suspension unit (leaf spring) 253 is arranged on the end surface of the second cover case 41 on the opening side opposite to the case 1. The second suspension unit 253 is formed by processing a thin plate of stainless steel (SUS304 in this embodiment), and has a second suspension 251 and a second suspension, which are leaf springs whose central portion is flexible along the vibration axis O. It is composed of a second elastic material 250 provided in 251.

The first suspension cover 71 is arranged so as to sandwich the first suspension unit 153 in cooperation with the first cover case 31. The second suspension cover 81 is arranged so as to sandwich the second suspension unit 253 in cooperation with the second cover case 41.

Three through holes 71a are formed along the edge of the first suspension cover 71 at a pitch of 120 °. The first cover case 31 is formed with three through holes 31a facing the holes 71a of the first suspension cover 71. Three female screw holes 1a facing the three holes 31a of the first cover case 31 are formed on the end surface on one opening side of the case 1.

Then, the peripheral portion of the first suspension 51 is brought into the first position by the three screws 91 which are inserted through the hole 71a of the first suspension cover 71 and the hole 31a of the first cover case 31 and screwed into the female screw hole 1a of the case 1. The first suspension cover 71, the first suspension unit 153, and the first cover case 31 are attached to one opening side of the case 1 in a state of being sandwiched between the suspension cover 71 and the first cover case 31. That is, the first suspension 51 is attached to the case 1 via the cover case 31.

Three through holes 81a are formed along the edge of the second suspension cover 81 at a pitch of 120 °. The second cover case 41 is formed with three through holes 41a facing the holes 81a of the second suspension cover 81. Three female screw holes (not shown) facing the three holes 41a of the second cover case 41 are formed on the other end surface of the case 1 on the opening side.

Then, the hole 81a of the second suspension cover 81 and the hole 41a of the second cover case 41 are inserted, and the three screws 101 formed on the other end surface of the case 1 on the opening side and screwed into the screw holes are used for the second suspension cover 81. 2 With the peripheral edge of the suspension 251 sandwiched between the second suspension cover 81 and the second cover case 41, the second suspension cover 81, the second suspension unit 253, and the second cover case 41 are the other of the case 1. It is attached to the opening side. That is, the second suspension 251 is attached to the case 1 via the cover case 41.

Between the first suspension unit 153 and the second suspension unit 253, a mover 111 surrounded by a coil 21 and vibrating along the vibration axis O is arranged. The mover 111 includes a disk-shaped magnet 113, a pair of disk-shaped first pole pieces 115 and second pole pieces 117 arranged so as to sandwich the magnet 113 along the vibration axis O, and a vibration axis O. It is composed of a pair of first mass (weight) 119 and second mass (weight) 121 arranged so as to sandwich the magnet 113, the first pole piece 115, and the second pole piece 117 along the above.

The cross-sectional area of the first mass 119 and the second mass 121 in the plane direction orthogonal to the vibration axis O direction is gradually narrowed toward the end of the case 1.
Further, in the vibration axis O direction, the height of the yoke 11 is larger than the height from one end to the other end of the pair of pole pieces (first hole piece 115, second hole piece 117), and the pair. The height of the weight (first square 119, second square 121) is set to be smaller than the height from one end to the other end.

The magnetizing direction of the magnet 113 is the vibration axis O direction. The first pole piece 115 and the second pole piece 117 are made of a soft magnetic material having a large magnetic permeability, and are attached to the magnet 113 by the magnetic attraction force of the magnet 113, an adhesive, or the like. The first mass 119 and the second mass 121 are made of a non-magnetic material such as brass or zinc die-cast, and are attached to the first pole piece 115 and the second pole piece 117 by an adhesive or the like. Therefore, the magnet 113, the first pole piece 115, the second pole piece 117, the first square 119, and the second square 121 constituting the mover 111 are integrated.

Holes 119a penetrating along the central axis and holes 121a penetrating are formed in the first square 119 and the second square 121. Further, at the center of the first suspension 51 and the first elastic material 150, a hole 51a and a hole 150a are formed so as to face the hole 119a of the first mass 119 and penetrate through the hole 119a. Similarly, at the center of the second suspension 251 and the second elastic material 250, a hole 251a and a hole 250a are formed so as to face the hole 121a of the second mass 121 and penetrate through the hole 121a.

Then, the pin 131 is inserted into the hole 51a and the hole 150a of the first suspension 51 and the first elastic material 150 and is press-fitted into the hole 119a of the first mass 119, and the pin 141 is the second suspension 251 and the second elastic material 250. By inserting the holes 251a and 250a and press-fitting them into the holes 121a of the second mass 121, the central portions of the first suspension 51 and the second suspension 251 bend in the vibration axis O direction.
The mover 111 is oscillatedly supported along the vibration axis O of the case 1.

That is, one end and the other end of the mover 111 in the vibration axis O direction are supported by the first suspension unit 153 and the second suspension unit 253, and the mover 111 is supported along the vibration axis O. It is possible to vibrate.
A lead wire (not shown) is connected to the peripheral surface of the case 1, and a terminal 3 for supplying a current to the coil 21 is formed.

The coil 21 will be described with reference to FIGS. 1-8.
The coil 21 of the present embodiment is arranged along the vibration axis O, and includes a first coil 23 and a second coil 25. The first coil 23 and the second coil 25 are wound along the inner peripheral surface of the yoke 11. Further, the yoke 11 is formed so as to project from the outside of the vibration axis O of the pair of coils 21 (first coil 23, second coil 25).

(Operation)
The operation of the vibration actuator 2 of the present embodiment will be described with reference to FIG.
When the first coil 23 and the second coil 25 are not energized, the mover 111 supported by the first suspension unit 153 and the second suspension unit 253 is located at the center of the coil 21.

The first coil 23 and the second coil 25 are alternately energized with alternating current in a direction in which a magnetic field of opposite polarity is generated. That is, the same pole is generated in the adjacent portions of the first coil 23 and the second coil 25.

In the polarity of FIG. 9, a downward thrust is generated in the mover 111 (in the direction of arrow A), and if the currents flowing through the first coil 23 and the second coil 25 are reversed, the mover 111 is in the upward direction (in the direction of arrow A). A thrust in the direction of the arrow B) is generated, and the first suspension unit 153 and the second suspension unit 253 are elastically deformed and moved upward.

In this way, if alternating current is applied to the first coil 23 and the second coil 25, the mover 111 receives the urging force of the case 1, the first suspension unit 153, and the second suspension unit 253 from both sides, and the vibration axis line. It vibrates along O.

By the way, the thrust generated in the mover 111 is basically based on the thrust given based on Fleming's left-hand rule. In the present embodiment, since the first coil 23 and the second coil 25 are fixed, a thrust as a reaction force of the force generated in the first coil 23 and the second coil 25 is generated in the mover 111.

Therefore, it is the horizontal component of the magnetic flux of the magnet 113 of the mover 111 (the component orthogonal to the axial direction of the magnet 113) that contributes to the thrust. The yoke 11 increases the horizontal component of the magnetic flux of the magnet 113.

(Effect of Examples)
According to the above configuration, the following effects can be obtained.
(1) Since the first mass 119 and the second mass 121 made of a non-magnetic material function as space-securing members, the cylindrical case 1 made of a resin which is a tubular non-magnetic material from the electromagnetic drive unit 10 that generates magnetic flux. The distance to the outer surface (outer surface) can be secured, and the leakage magnetic flux can be reduced by using the light resin case 1 without using a special heavy metallic magnetic shielding case, so that the vibration actuator can be made smaller and lighter. ..

(2) A first suspension unit 51 having one end attached to one end of the mover 111 in the vibration axis O direction and the other end attached to the case 1 and the other end of the mover 111 in the vibration axis O direction. The mover 111 is oscillatedly supported along the vibration axis O by a second suspension unit 251 having one end attached to one end and the other end attached to the case 1.
Therefore, the force required when the mover 111 starts to vibrate is a force that elastically deforms the first suspension unit 153 and the second suspension unit 253. Since the force for elastically deforming the first suspension unit 153 and the second suspension unit 253 is smaller than the static friction force generated between the shaft and the bearing in the conventional vibration actuator, a small driving force is required. Therefore, since the vibration force can be obtained even with a small AC signal, a vibration actuator with high tactile reproducibility can be realized.

(3) Since the conventional mover does not have a metal shaft protruding to the outside of the case, the leakage magnetic flux in the vibration axis O direction is also reduced.

(4) The cross-sectional area of the first mass 119 and the second mass 121 in the plane direction orthogonal to the vibration axis O direction is gradually narrowed toward the end of the case 1, so that the mover 111 has the vibration axis O. When vibrating in the direction, the flexible portion (central portion) of the first mass 119 and the first suspension 51, and the flexible portion (central portion) of the second mass 121 and the second suspension 251 come into contact with each other to generate an abnormal noise. And the spatial distance can be secured without limiting the amplitude range. Therefore, until the leakage magnetic flux in the vibration axis O direction can be reduced to the same extent as the leakage magnetic flux in the plane direction orthogonal to the vibration axis O having magnetic shielding by the electromagnetic drive unit, the vibration axis O of the first mass 119 and the second mass 121 Even if the length in the direction is lengthened, the weight of the vibration actuator 2 can be reduced.

The applicant analyzed the leakage magnetic flux of the vibration actuator having the structure shown in the embodiment in order to confirm the effect of the present invention. The external dimensions of the vibration actuator are φ25 mm in diameter and 30 mm in height.

FIG. 10 is a diagram showing the magnetic flux density distribution of the leakage magnetic flux of the vibration actuator, and FIG. 11 is a distance (mm) from the center 300 in the vibration actuator vibration axis direction in the Z-axis (vibration axis) direction and the leakage magnetic flux density (FIG. 10). The figure showing the relationship with mT), FIG. 12 shows the distance (mm) and the leakage magnetic flux density (mm) from the outer shape (outer surface) 301 of the vibration actuator in the X-axis (axis on the plane orthogonal to the vibration axis) direction in FIG. It is a figure which shows the relationship with mT).

As shown in these figures, by appropriately selecting the shapes of the first and second masses, the leakage magnetic flux in the Z-axis direction (vibration axis O direction) is in the X-axis direction with magnetic shielding by the yoke of the electromagnetic drive unit. It was confirmed that the leakage magnetic flux (in the axial direction on the plane orthogonal to the vibration axis O) can be reduced to the same extent.

1 Case 2 Vibration axis 10 Electromagnetic drive 11 York 21 Coil 51 First suspension (leaf spring)
111 Movable element 113 Magnet 115 1st pole piece 117 2nd pole piece 119 1st square (weight)
121 2nd square (weight)
153 1st suspension unit 251 2nd suspension (leaf spring) spring 253 2nd suspension unit 300 Vibration actuator Center in vibration axis 301 External shape (outer surface) spring of vibration actuator

Claims (4)

A case made of a tubular non-magnetic material and
A tubular electromagnetic drive unit provided inside the case,
A mover provided on the inside in the radial direction of the electromagnetic drive unit and supported so as to vibrate along the vibration axis, and a mover.
A pair of leaf springs that support one end and the other end of the mover in the vibration axis direction, respectively.
Have,
The mover is
With a magnet
A pair of pole pieces made of a soft magnetic material sandwiching the magnet from both sides along the vibration axis,
A pair of weights made of non-magnetic material sandwiching the pair of pole pieces from both sides along the vibration axis,
Have,
The electromagnetic drive unit
A pair of coils arranged at intervals along the vibration axis and each formed in a cylindrical shape,
A cylindrical yoke made of a soft magnetic material, which is arranged radially outside the pair of coils and is formed so as to project outward in the vibration axis direction from the pair of coils.
Have,
In the vibration axis direction, the height of the yoke is larger than the height from one end to the other end of the pair of pole pieces, and is larger than the height from one end to the other end of the pair of weights. A vibration actuator characterized by its small size. The vibration actuator according to claim 1, wherein the cross-sectional area of the weight in the plane direction orthogonal to the vibration axis is gradually narrowed toward the end of the tubular case. The vibration actuator according to claim 1 or 2, wherein the height of each weight of the pair of weights is larger than the height of each pole piece of the pair of pole pieces in the vibration axis direction. The case is
The vibration actuator according to any one of claims 1 to 3, wherein the vibration actuator is made of a resin.

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