JP7580538B2 - Vibration Actuator - Google Patents

Description

The present invention relates to a low-cost vibration actuator.

Cylindrical yokes used in vibration actuators and linear actuators are formed by punching out a flat plate and bending it into a cylinder (see, for example, Patent Documents 1 and 2).
The cylindrical yoke molded by the above method is then press-fitted into a die to improve dimensional accuracy (see, for example, Patent Document 3).

Japanese Utility Model Publication No. 61-045745 Japanese Utility Model Application Publication No. 58-097957 Patent No. 3965124

However, a vibration actuator using a cylindrical yoke manufactured by the above-mentioned method of improving dimensional accuracy using a mold has a problem of being costly.
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 having a yoke which is low cost and has good dimensional accuracy.

A vibration actuator of the invention according to claim 1 which solves the problem comprises a cylindrical case, a pair of cylindrical coils provided inside the case, a cylindrical yoke made of a soft magnetic material provided inside the case, a mover provided inside the case and radially inward of the pair of coils and the yoke and supported so as to be vibrable along a vibration axis, and a pair of dampers respectively supporting one end and the other end of the mover in the direction of the vibration axis, wherein the mover comprises a magnet, a pair of pole pieces made of a soft magnetic material which sandwich the magnet from both sides along the vibration axis, and a pair of weights made of a non-magnetic material which abuts against and sandwiches the pair of pole pieces from both sides along the vibration axis, wherein the yoke increases the magnetic flux of a horizontal component of the magnet which contributes to a thrust applied to the mover, and the vibration of the mover is regulated based on a change in the thrust applied to the mover which is based on a change in the axial relative position of the magnet and the yoke , and on the biasing force of the damper.

Other features of the present invention will become more apparent from the detailed description of the invention described below and the accompanying drawings.

According to the vibration actuator of the present invention, the yoke is composed of multiple rectangular split yokes formed by cutting a cylinder along different generatrix lines. The split yokes can be formed by low-cost manufacturing methods such as press processing and have good dimensional accuracy, making it possible to realize a vibration actuator with a yoke that is low-cost and has good dimensional accuracy.

Other advantages of the present invention will become more apparent from the detailed description of the invention and the accompanying drawings described below.

1 is an exploded perspective view illustrating an embodiment of a vibration actuator of the present invention. FIG. 2 is a top view of the assembled state of FIG. 1 . FIG. 3 is a front view of FIG. 2 . FIG. 3 is a rear view of FIG. 2 . FIG. 3 is a bottom view of FIG. 2 . FIG. 4 is a left side view of FIG. 3 . 7 is a cross-sectional view taken along line VII-VII in FIG. 2. 11A and 11B are diagrams illustrating a method of attaching a split yoke to a case. 11A and 11B are diagrams illustrating a method of attaching a coil to a case to which a split yoke is attached. 11 is a diagram illustrating a case in which a split yoke and a coil are attached. FIG. 2A to 2C are diagrams illustrating the operation of the vibration actuator shown in FIG. 1 . 13A to 13C are diagrams illustrating the operation of a vibration actuator according to another embodiment.

The embodiments will be described with reference to the drawings. Fig. 1 is an exploded perspective view for explaining an embodiment of the vibration actuator of the present invention, Fig. 2 is a top view of Fig. 1 when assembled, Fig. 3 is a front view of Fig. 2, Fig. 4 is a rear view of Fig. 2, Fig. 5 is a bottom view of Fig. 2, Fig. 6 is a left side view of Fig. 3, Fig. 7 is a cross-sectional view taken along the line VII-VII of Fig. 2, Fig. 8 is a view for explaining a method of attaching a split yoke to a case, Fig. 9 is a view for explaining a method of attaching a coil to a case to which a split yoke is attached, Fig. 10 is a view for explaining a case to which a split yoke and a coil are attached, Fig. 11 is a view for explaining the operation of the vibration actuator shown in Fig. 1, and Fig. 12 is a view for explaining the operation of a vibration actuator of another embodiment. The right side of Fig. 3 is the same as the left side of Fig. 6.
(Overall composition)
The overall configuration of a vibration actuator will be described with reference to FIGS.

A cylindrical case 1 made of resin such as ABS having openings at both ends is provided inside the case 1. A cylindrical yoke 11 made of a soft magnetic material is attached to the inner peripheral surface of the yoke 11 while being electrically insulated from the yoke 11.
A cylindrical first cover case 31 made of resin such as ABS is disposed on one open end face of the case 1. A cylindrical second cover case 41 made of resin such as ABS is disposed on the other open end face of the case 1.

A first damper 51 made of a thin stainless steel plate is disposed on the end surface of the opening of the first cover case 31 opposite the case 1, and is flexible along the vibration axis O of the case 1. A second damper 61 made of a thin stainless steel plate is disposed on the end surface of the opening of the second cover case 41 opposite the case 1, and is flexible along the vibration axis O of the case 1.

A first damper cover 71 is disposed so as to cooperate with the first cover case 31 to sandwich the first damper 51. A second damper cover 81 is disposed so as to cooperate with the second cover case 41 to sandwich the second damper 61.
Three through holes 71a are formed at 120° intervals along the edge of the first damper cover 71. Three through holes 31a are formed in the first cover case 31, which face the holes 71a in the first damper cover 71. Three female threaded holes 1a are formed in the end face on one opening side of the case 1, which face the three holes 31a in the first cover case 31.

The first damper 51 is clamped between the first damper cover 71 and the first cover case 31 by three screws 91 that pass through the holes 71a of the first damper cover 71 and the holes 31a of the first cover case 31 and screw into the female threaded holes 1a of the case 1, and the first damper cover 71, the first damper 51, and the first cover case 31 are attached to one opening side of the case 1.

Three through holes 81a are formed at 120° intervals along the edge of the second damper cover 81. Three through holes 41a are formed in the second cover case 41, which face the holes 81a in the second damper cover 81. Three female threaded holes (not shown) are formed in the end face on the other opening side of the case 1, which face the three holes 41a in the second cover case 41.

The second damper 61 is sandwiched between the second damper cover 81 and the second cover case 41 by three screws 101 that pass through the holes 81a of the second damper cover 81 and the holes 41a of the second cover case 41 and screw into female threaded holes formed in the end face of the other opening side of the case 1, and the second damper cover 81, the second damper 61, and the second cover case 41 are attached to the other opening side of the case 1.

Between the first damper 51 and the second damper 61, a mover 111 is arranged, surrounded by the coil 21, and vibrating along the vibration axis O. The mover 111 is composed of a disk-shaped magnet 113, a disk-shaped first pole piece 115 and a disk-shaped second pole piece 117 arranged to sandwich the magnet 113, and a first mass (weight) 119 and a second mass (weight) 121 arranged to sandwich the magnet 113, the first pole piece 115, and the second pole piece 117.

The magnet 113 is magnetized in the direction of the vibration axis O. The first pole piece 115 and the second pole piece 117 are made of a hard-to-magnetic material and are attached to the magnet 113 by the magnetic attraction of the magnet 113 and by adhesive or the like. The first mass 119 and the second mass 121 are made of a non-magnetic material and are attached to the first pole piece 115 and the second pole piece 117 by adhesive or the like. Therefore, the magnet 113, the first pole piece 115, the second pole piece 117, the first mass 119, and the second mass 121 that make up the mover 111 are integrated.

The first mass 119 and the second mass 121 have a through hole 119a and a through hole 121a formed along the central axis. Furthermore, a through hole 51a is formed in the center of the first damper 51, facing the hole 119a of the first mass 119. Similarly, a through hole 61a is formed in the center of the second damper 61, facing the hole 121a of the second mass 121.

The pin 131 is inserted through the hole 51a of the first damper 51 and press-fitted into the hole 119a of the first mass 119, and the pin 141 is inserted through the hole 61a of the second damper 61 and press-fitted into the hole 121a of the second mass 121, so that the mover 111 is supported so as to be able to vibrate along the vibration axis O of the case 1.

A terminal 3 is formed on the periphery of the case 1 to which a lead wire is connected and which supplies a current to the coil 21 .
(Case 1, yoke 11, coil 21)
This will be explained with reference to Figures 8 to 10.
The yoke 11 of this embodiment is composed of a plurality of (three in this embodiment) rectangular split yokes 13 formed by cutting a cylinder along different generatrix lines.

Moreover, the coil 21 of the present embodiment is disposed along the vibration axis O, and is made up of a first coil 23 and a second coil 25. The first coil 23 and the second coil 25 are wound around the inner circumferential surface of the yoke 11.
On the inner peripheral surface of the case 1, three ribs 5 are formed at equal intervals so as to protrude in the direction of the vibration axis O and extend in the direction of the vibration axis O.

The two end faces of each rib 5 in the direction of the vibration axis O are formed with split yoke abutment faces 5a against which the end faces along the generatrix of the split yoke 13 abut. In this embodiment, the rib 5 is made of resin and has elasticity. Therefore, the two end faces along the generatrix of the split yoke 13 abut.

The end faces of the split yoke 13 along the generatrix abut against the split yoke abutment surfaces 5 a of the ribs 5 , thereby positioning the split yoke 13 in the circumferential direction of the case 1 .
Furthermore, a protrusion 7 that protrudes toward the mover 111 is formed on a surface 5b of each rib 5 that faces the magnet 113 of the mover 111. A first coil abutment surface 7a is formed on one opening side of the case 1 of the protrusion 7, against which an end of the first coil 23 on the opening side abuts. A second coil abutment surface 7b is formed on the other opening side of the case 1 of the protrusion 7, against which an end of the second coil 25 on the opening side abuts.

The end of the first coil 23 on the opening side abuts against the first coil abutment surface 7a of the protrusion 7 of the rib 5, and the first coil 23 is positioned in the direction of the vibration axis O of the case 1, and then the first coil 23 is attached to the yoke 11 using adhesive or the like. The end of the second coil 25 on the opening side abuts against the second coil abutment surface 7b of the protrusion 7 of the rib 5, and the second coil 25 is positioned in the direction of the vibration axis O of the case 1, and then the second coil 25 is attached to the yoke 11 using adhesive or the like.

(Operation)
The operation of the vibration actuator of this embodiment will be described with reference to FIG.
When no current is applied to the first coil 23 and the second coil 25 , the mover 111 supported by the first damper 51 and the second damper 61 is located in the center of the coil 21 .

An alternating current is passed through the first coil 23 and the second coil 25 in a direction that generates magnetic fields of opposite polarity alternately. That is, the same polarity is generated in adjacent portions of the first coil 23 and the second coil 25.
With the polarity in Figure 11, a downward thrust (in the direction of arrow A) is generated in the mover 111, and if the current flowing through the first coil 23 and the second coil 25 is reversed, an upward thrust (in the direction of arrow B) is generated in the mover 111.

In this manner, when an alternating current is applied to the first coil 23 and the second coil 25, the movable member 111 vibrates along the vibration axis O while receiving biasing forces from the case 1, the first damper 51, and the second damper 61 from both sides.
The thrust generated in the mover 111 basically conforms to the thrust given based on Fleming's left-hand rule. In this embodiment, since the first coil 23 and the second coil 25 are fixed, a thrust is generated in the mover 111 as a reaction force against the force generated in the first coil 23 and the second coil 25.

Therefore, what contributes to the thrust is the horizontal component of the magnetic flux of the magnet 113 of the mover 111 (the component perpendicular to the axial direction of the magnet 113). The yoke 11 increases the horizontal component of the magnetic flux of the magnet 113.
According to the above configuration, the following effects can be obtained.

(1) The yoke 11 is composed of multiple rectangular split yokes 13 formed by cutting a cylinder along different generatrix lines. The split yokes 13 can be formed by a manufacturing method such as press processing that is inexpensive and has good dimensional accuracy, making it possible to realize a vibration actuator having a yoke with good dimensional accuracy at low cost.

(2) Since the first coil 23 and the second coil 25 are provided using the protrusion 7 on the rib 5 as a guide, the bobbin (cylinder) that was previously required to hold the coils is no longer necessary, making it possible to realize a small vibration actuator.
(3) The end faces of the split yoke 13 along the generatrix abut against the split yoke abutment surfaces 5 a of the ribs 5 , so that the split yoke 13 can be positioned in the circumferential direction of the case 1 .

In the above embodiment, the two end faces of the split yoke 13 along the generatrix are pressed between the split yoke abutment surfaces 5a of the adjacent elastic ribs 5. However, the split yoke 13 can be positioned in the circumferential direction of the case 1 by abutting one of the two end faces along the generatrix of the split yoke 13 against the split yoke abutment surface 5a of the rib 5.

(4) The end of the first coil 23 on the opening side abuts against the first coil abutment surface 7a of the protrusion 7 of the rib 5, thereby enabling the first coil 23 to be positioned in the direction of the vibration axis O of the case 1. In addition, the end of the second coil 25 on the opening side abuts against the second coil abutment surface 7b of the protrusion 7 of the rib 5, thereby enabling the second coil 25 to be positioned in the direction of the vibration axis O of the case 1.

The present invention is not limited to the above embodiment.
In the above embodiment, the coil 21 is described as being made up of two coils, the first coil 23 and the second coil 25, but as shown in Fig. 12, it may be made up of a single coil 221. In this case, the magnet of the mover 311 is magnetized in the radial direction.

1 Case 11 Yoke 13 Split yoke 21 Coil 111 Movable element 113 Magnet

Claims (6)

A cylindrical case and
A pair of cylindrical coils provided inside the case;
a cylindrical yoke made of a soft magnetic material provided inside the case;
a movable element provided inside the case, disposed radially inward of the pair of coils and the yoke, and supported so as to be capable of vibrating along a vibration axis;
a pair of dampers supporting one end and the other end of the movable element in the vibration axis direction,
The mover is
A magnet and
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 a non-magnetic material sandwiching the pair of pole pieces in contact with each other along the vibration axis;
having
the yoke increases a horizontal component of magnetic flux of the magnet that contributes to a thrust applied to the mover,
the vibration of the mover is regulated based on a change in thrust applied to the mover, which is based on a change in the relative position of the magnet and the yoke in the axial direction, and based on the biasing force of the damper;
The damper is a flexible thin plate,
the case is made of resin,
An end of the yoke extends outwardly of the coil and inwardly of the damper in the vibration axis direction.
A vibration actuator comprising: A cylindrical case and
A pair of cylindrical coils provided inside the case;
a cylindrical yoke made of a soft magnetic material provided inside the case;
a movable element provided inside the case, disposed radially inward of the pair of coils and the yoke, and supported so as to be capable of vibrating along a vibration axis;
a pair of dampers supporting one end and the other end of the movable element in the vibration axis direction,
The mover is
A magnet and
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 a non-magnetic material sandwiching the pair of pole pieces in contact with each other along the vibration axis;
having
the yoke increases a horizontal component of magnetic flux of the magnet that contributes to a thrust applied to the mover,
The vibration of the mover is regulated based on the horizontal component of the magnetic flux of the magnet and the biasing force of the damper,
The damper is a flexible thin plate,
the case is made of resin,
An end of the yoke extends outwardly of the coil and inwardly of the damper in the vibration axis direction.
A vibration actuator comprising: A cylindrical case and
A pair of cylindrical coils provided inside the case;
a cylindrical yoke made of a soft magnetic material provided inside the case;
a movable element provided inside the case, disposed radially inward of the pair of coils and the yoke, and supported so as to be capable of vibrating along a vibration axis;
a pair of dampers supporting one end and the other end of the movable element in the vibration axis direction,
The mover is
A magnet and
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 a non-magnetic material sandwiching the pair of pole pieces in contact with each other along the vibration axis;
having
The mover is disposed within a range of the yoke that increases the magnetic flux of the horizontal component of the magnet;
a vibration range of the mover is set based on a reaction force acting as a result of a reduction in the horizontal component of the magnetic flux when the mover vibrates and on a reaction force of the damper,
The damper is a flexible thin plate,
the case is made of resin,
An end of the yoke extends outwardly of the coil and inwardly of the damper in the vibration axis direction.
A vibration actuator comprising: A vibration actuator according to any one of claims 1 to 3, wherein the yoke is positioned centrally from the head of the pin in the vibration direction of the mover. A vibration actuator according to any one of claims 1 to 4, wherein the yoke has a gap in the circumferential direction. 4. The vibration actuator according to claim 1, wherein an amplitude movable range of said one end and said other end of said mover in said vibration axis direction is limited.