JP7293531B2 - actuator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an actuator that generates vibrations by utilizing heat-induced contraction of shape memory alloys.

For example, mobile terminals such as smartphones, so-called VR (virtual reality) game machines, and the like are equipped with actuators (vibration devices) that transmit vibrations to users. This type of actuator as a user interface that utilizes the tactile sensation of the skin is small and lightweight, and can give a strong tactile sensation to the user when the acceleration is large. Therefore, it is desirable to obtain a large acceleration. In addition, along with the thinning of various terminal devices, thinning of the actuator itself is desired.

As this type of actuator, there is an actuator that uses a shape memory alloy and moves a moving member away from and close to a stator to generate vibration.

Patent Documents 1 and 2, for example, exist as the actuator described above.

Patent Documents 1 to 3 have a wire made of a conductive shape memory alloy, and the wire expands and contracts due to heat generation when energized and cooling when not energized. Vibration is generated by resetting.

Patent No. 6046980 JP 2019-2373 A

Such an actuator applies an urging force in a direction to press the mover toward the stator in order to return the mover, which has separated from the stator due to contraction of the wire, to its original position.

For example, in Patent Document 1, stepped screws are screwed to the stator at both ends of the mover, and a compression coil spring inserted through the stepped screws is compressed to create an urging force that presses the mover against the stator side. is giving

In addition, in Patent Document 2, the stator has protrusions longer than the mover (movable element) at both ends in the longitudinal direction. The biasing force is applied by pressing the slider at the other end of the .

However, in Patent Documents 1 and 2, in order to hold down one side of the mover, Patent Document 1 uses two parts, a stepped screw and a compression coil spring, Patent Document 2 uses two parts, a biasing member and a male thread member. each need. For this reason, the number of parts is large, the number of assembly man-hours is increased, and the process involved in handling the parts is complicated. Further, in the configurations of Patent Document 1 and Patent Document 2, the actuator is enlarged in the longitudinal direction and the lateral direction in order to secure a space for attaching the stepped screw and the male screw member.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its object is to provide an actuator that can be easily assembled while suppressing the increase in size, reducing the number of parts and assembly man-hours. That's what it is.

In order to achieve the above object, the actuator according to the present invention comprises a stator, a mover facing the stator and provided so as to be able to approach and move away from the stator, and the mover and the stator. a contractible wire made of a shape memory alloy disposed between; a cover fixed to the stator and covering the mover; and a cover disposed between the mover and the cover, the mover and a biasing member that biases toward the stator.

In the above actuator, the urging member is a leaf spring having a middle portion that is in pressure contact with one of the mover and the cover, and both side portions that are in pressure contact with the other of the mover and the cover. good too.

In the above actuator, the leaf spring has an inwardly folded portion folded inward from both ends in the longitudinal direction of the base, and an outwardly folded portion folded outwardly from the inner end of the inwardly folded portion. may have.

In the actuator described above, the plate spring may be provided with an engagement hole, and the slider may be provided with a positioning protrusion that engages with the engagement hole.

In the actuator described above, the cover may cover the facing portion between the stator and the mover.

In the actuator described above, the cover may restrict movement of the mover in a lateral direction.

In the actuator described above, the cover may have a shape in which the stator side is open.

In the actuator described above, the cover may be a press-molded product.

ADVANTAGE OF THE INVENTION According to this invention, the enlargement of an actuator can be suppressed, the number of parts and an assembly man-hour can be reduced, and it can be easily assembled.

FIG. 4 is an explanatory diagram illustrating the operation principle of the present invention and showing a state in which the wire made of a shape memory alloy is cold; FIG. 4 is an explanatory view showing the operating principle of the present invention, showing a state in which the wire shrinks due to heat and pushes up the slider; FIG. 10 is an explanatory diagram illustrating the operation principle of the present invention, showing a state in which the wire is cooled and the mover returns to its original position due to the biasing force acting on the mover; 1 is a front view of an actuator according to one embodiment of the invention; FIG. 1 is a front view of an actuator according to an embodiment of the invention, with a cover removed; FIG. 1 is an exploded perspective view of an actuator according to one embodiment of the present invention; FIG. 5 is a longitudinal side view along line VII-VII of FIG. 4; FIG. FIG. 8 is a longitudinal front view along line VIII-VIII of FIG. 7;

First, prior to the embodiment of the present invention, the operating principle of the actuator used in the present embodiment will be described with reference to FIGS. 1 to 3. FIG.

In FIG. 1, 1 is a stator which is one of the main members constituting the actuator, and 2 is a mover. A linear wire 3 made of a shape memory alloy is arranged between the stator 1 and the mover 2 . 4 is an electric wire connected to the wire 3 made of shape memory alloy, 5 is a power source, and 6 is a power switch for turning on and off. When turned on, the wire 3 made of shape memory alloy is energized. FIG. 1 shows a state in which the switch 6 is off and the mover 2 is close to the stator 1 side.

FIG. 2 shows a state in which the switch 6 is turned on and the wire 3 is energized. Electric current flows through the wire 3 and the wire 3 heats up, causing the wire 3 to shrink, and as indicated by the white arrow, a thrust force is generated in the direction to move the mover 2 away from the stator 1, and the mover 2 moves away from the stator. Move away from 1.

When the switch 6 is turned off, no current flows through the wire 3 and the wire 3 is cooled. As shown in FIG. 3, since a biasing force acts on the mover 2 in the direction of the white arrow, the wire 3 is stretched, and the mover 2 moves again toward the stator 1, returning to the original state shown in FIG. becomes. Vibration is generated by repeating a series of these operations.

An embodiment of the present invention will be described below. 4 is a front view of an actuator A according to an embodiment of the present invention, FIG. 5 is a front view with the cover removed, FIG. 6 is an exploded perspective view of the actuator A, and FIG. 7 is taken along line VII-VII in FIG. FIG. 8 is a longitudinal front view along line VIII-VIII of FIG. The overall configuration of the actuator A of one embodiment will be described with reference to FIGS. 4 to 8. FIG. As shown in FIG. 6, the lateral direction of the actuator A is the X direction, the lateral direction is the Y direction, and the vertical direction is the Z direction.

In the figure, 10 is a stator, 20 is a mover disposed opposite to the stator 10 in the illustrated state, and a wire 30 made of a shape memory alloy is provided between them. This corresponds to the stator 1, mover 2 and wires 3 shown in FIGS. Reference numeral 40 denotes a leaf spring which is an urging member for urging the mover 20 toward the stator 10; FIG. 4 shows the state in which they are assembled, and FIG. 5 shows the state in which the cover 50 is removed therefrom.

The stator 10 comprises a base member 11 made of an insulating synthetic resin material and a stator main body 12 made of a synthetic resin material having a high heat dissipation property molded into the base member 11 . The base member 11 is composed of a pair of mounting pieces 11a connected by a plate-shaped connecting piece 11b (see FIG. 7) facing in the longitudinal direction (Y direction). , a plurality of projections 11c for increasing the coupling force with the stator main body 12 are protruded at appropriate intervals. As shown in FIG. 4, the pair of mounting pieces 11a has a portion that protrudes downward from the lower end of the cover 50 when the cover 50 is mounted on the stator 10, and the entire actuator A is mounted on a device (not shown) to be used. A mounting hole 11d is provided for this purpose. Terminals 13 for attaching the wires 30 to the stator 10 are fixed with rivets 14 to portions of the pair of attachment pieces 11a above the attachment holes 11d. Further, the cover 50 is fixed with rivets 15 to the inner side of the rivet 14 attachment portions of the pair of attachment pieces 11a.

The stator main body 12 and the mover 20 are insulating heat conductors and made of insulating synthetic resin material or the like. It is preferable to use a material having high insulating and heat dissipation properties for the material forming the stator main body 12 and the mover 20 . Polyphenylene sulfide (hereinafter referred to as PPS), which is a thermoplastic resin having particularly high heat resistance, wear resistance, and dimensional stability, is suitable for the stator main body 12 and the mover 20 . Furthermore, when PPS is used for the stator 10 and the mover 20, fine particles of a thermally conductive filler that enhances thermal conductivity are dispersed in the PPS. effective in improving In addition, as a material for forming the stator 10 and the mover 20, a metal material such as aluminum having a good heat dissipation property and subjected to an insulation treatment may be used. As the synthetic resin material, a polyamide synthetic resin may be used in addition to the PPS.

The stator 10 has a substantially rectangular parallelepiped shape elongated in the Y direction. The upper surface of the stator 10 (the surface facing the mover 20) has a wavy portion in which the stator-side depressions 16 and the stator-side protrusions 17 are alternately formed in the Y direction. In this embodiment, six stator-side depressions 16 and five stator-side projections 17 are formed, but the numbers of stator-side depressions 16 and stator-side projections 17 are limited to these. It is not something that can be done.

As shown in FIG. 6, the bottom surface 16a of the stator-side recessed portion 16 is formed in a concave arc shape curved in the Y direction of the stator 10 with a first curvature. Further, in the stator-side recessed portion 16, a stator-side projecting piece 16b projecting from the bottom surface 16a is formed in the center portion in the X direction (transverse direction) perpendicular to the Y direction. The top surface of the stator-side projecting piece 16b is curved in the Y direction of the stator 10 with the same first curvature as that of the bottom surface 16a.

In addition, the top surface 17a of the stator-side protrusion 17 is formed in a convex arc shape curved in the Y direction of the stator 10 with a second curvature larger than the first curvature (that is, the radius of curvature is smaller). . Furthermore, a stator-side groove 17b recessed from the top surface 17a is formed in the center of the stator-side projection 17 in the X direction. The bottom surface of the stator-side groove portion 17b is curved in the longitudinal direction of the stator 10 with the same second curvature as the top surface 17a.

In this manner, the stator-side projecting pieces 16b and the stator-side grooves 17b are alternately formed in the X-direction central portion of the wavy portion of the stator 10, and the bottom surface 16a and the top surface 17a are formed on both sides in the X-direction. A wavy shape with a smaller height difference than the wavy shape is formed. Each corner of the stator-side protruding piece 16b and the stator-side groove portion 17b is subjected to R-chamfering and R-grooving.

Wire guide portions 18 for inserting and guiding the wire 30 from the ends of the wavy portion to the terminal 13 are provided on both Y-direction end sides of the wavy portion of the stator 10 and outside the left and right outermost stator-side depressions 16 . is provided. The wire guide portion 18 is formed in a convex arc shape that curves in the Y direction.

Like the stator 10, the mover 20 also has a substantially rectangular parallelepiped shape elongated in the Y direction. Further, the lower surface of the mover 20 (the surface facing the stator 10) has a wavy portion in which mover-side depressions 21 and mover-side protrusions 22 are alternately formed in the Y direction. In this embodiment, five slider-side depressions 21 and six slider-side protrusions 22 are formed, but the number of slider-side depressions 21 and slider-side protrusions 22 is limited to this. It is not something that can be done.

The bottom surface 21a of the mover-side recessed portion 21 is like the bottom surface 16a of the stator-side recessed portion 16 (vertical symmetry), and is curved in the Y direction with the same first curvature as the bottom surface 16a of the stator 10. is formed in Further, the mover-side recessed portion 21 has a mover-side protruding piece 21b (see FIG. 8) protruding from the bottom surface 21a at the center in the X direction. The top surface of the mover-side protruding piece 21b is curved in the Y direction of the mover 20 with the same first curvature as the bottom surface 21a.

The top surface 22a of the mover-side protrusion 22 is formed in a convex arc shape curved in the Y direction of the mover 20 with the same second curvature as the top surface 12a of the stator 10 . Further, the mover-side protrusion 22 is formed with a mover-side groove 22b recessed from the top surface 22a at the center in the X direction. The bottom surface of the mover-side groove portion 22b is curved in the Y direction of the mover 20 with the same second curvature as the top surface 22a.

In this manner, the moving element-side projecting pieces 21b and the moving element-side grooves 22b are alternately formed in the X-direction central portion of the wavy portion of the moving element 20, and the bottom surface 21a and the top surface 22a are formed at both ends in the X-direction. A wavy shape with a smaller height difference than the wavy shape is formed. Each corner of the mover-side protruding piece 21b and the mover-side groove portion 22b is subjected to R chamfering and R groove processing.

The wavy portion of the stator 10 and the wavy portion of the mover 20 are engageable with each other with the wire 30 sandwiched therebetween. Specifically, as shown in FIG. 5 , the stator-side depression 16 is engaged with the slider-side protrusion 22 , and the stator-side depression 21 is engaged with the stator-side protrusion 17 . In this way, the wire 30 extends between the stator-side projecting piece 16b of the stator-side recessed portion 16 and the mover-side grooved portion 22b of the mover-side projecting portion 22 and between the mover-side projecting piece of the mover-side recessed portion 21. 21b and the stator-side groove portion 17b of the stator-side projection portion 17. As shown in FIG. Further, by engaging the stator-side recessed portion 16 and the mover-side projection portion 22 and the mover-side recessed portion 21 and the stator-side projection portion 17 in this manner, the gap between the stator 10 and the mover 20 is reduced. are restricted in the Y and X directions, and the Z-direction movement of the mover 20 with respect to the stator 10 is smoothly guided.

The curvature of the top surface of the stator-side projecting piece 16b, the bottom surface of the stator-side grooved portion 17b, the top surface of the mover-side projecting piece 21b, and the bottom surface of the mover-side grooved portion 22b are all different from the stator in which they are provided. The curvatures of the bottom surface 16a of the side recess 16, the top surface 17a of the stator-side protrusion 17, the bottom surface 21a of the slider-side recess 21, and the top surface 22a of the slider-side protrusion 22 are substantially the same. may be smaller than the latter so that the corrugated deformation of the wires 30 sandwiched by them is smoother.

The wire 30 is made of a shape memory alloy such as a nickel-titanium alloy or a nickel-titanium-copper alloy. The wire 30 is arranged between the protruding pieces 16b and the grooves 17b and 22b of the stator 10 and the mover 20, and sandwiched between the stator 10 and the mover 20 so that the wire 30 is in a non-energized state. , the wave shape corresponds to these wave shapes (see FIG. 8).

Both ends of the wire 30 are attached to a pair of attachment pieces 11 a of the stator 10 via terminals 13 . Terminals 13 are made of a conductor and fixed to stator 10 with rivets 14 . A wire attachment portion 13 a is provided at one end of the terminal 13 . A groove 13b through which the wire 30 is inserted and fixed is formed in the wire attachment portion 13a. The wire attachment portion 13a fixes the wire 30 by crimping the wire 30 in a crank shape while the wire 30 is inserted into the groove 13b. This crank shape prevents the wire 30 from loosening when it expands and contracts.

A wire connecting piece 13c for connecting an electric wire (not shown) is formed on the other end side of the terminal 13 .

Mounting pieces 23 project upward from the upper end of the cover 50 when the cover 50 is mounted on both sides of the upper surface of the mover 20 . Each mounting piece 23 is provided with a mounting hole 24 for mounting another component (not shown). A grommet 24 a made of a synthetic resin material is fitted in the mounting hole 24 .

A concave portion 25 for accommodating the leaf spring 40 is formed in the middle portion of the upper surface of the mover 20, and a protrusion 26 for positioning the leaf spring 40 is provided in the center thereof.

The cover 50 has an upper piece 51 covering the upper surface of the mover 20 and a pair of front and rear side pieces 52 hanging down from the front and rear edges of the upper piece 51. The lower end in the Z direction and both ends in the Y direction are open. It is assumed that the shape is Both ends of the upper piece 51 in the Y direction are provided with notches 53 through which the left and right mounting pieces 23 of the mover 20 are inserted upward. The cover 50 is placed over the assembly in which the stator 10, the wire 30, the mover 20, and the spring member 40 are assembled, and is fixed to the mounting pieces 11a of the stator 10 with rivets 15 as shown in FIG. ing.

A plurality of guide ribs 27 are provided on both sides of the mover 20 in the X direction to reduce the contact area with the inner surface of the side piece 52 of the cover 50 . Each rib 27 has an elongated shape along the Z direction, which is the moving direction of the mover 20 . The contact between the ribs 27 and the cover 50 can reduce the friction between the mover 20 and the cover 50 when the mover 20 moves in the Z direction. Further, the movable element 20 can be smoothly guided along the side pieces 52 of the cover 50, and the movable element 20 can be smoothly moved toward and away from the stator 10. - 特許庁The number of ribs 27 is arbitrary. Also, the rib 27 can be provided on the inner surface of the side piece 52 of the cover 50 or can be provided on both the cover 50 and the mover 20 .

The plate spring 40 includes a base portion 41 elongated in the Y direction, inward folded portions 42 folded upward and inward from both ends thereof, and an arc-shaped curved portion 43 extending upward and outward from the inner ends thereof. It is composed of an outwardly folded portion 44 that is folded back. An engagement hole 45 is provided in the central portion of the base portion 41 for engaging with the protrusion 26 of the mover 20 to position the leaf spring 40 on the mover 20 .

The leaf spring 40 is housed in the recess 25 of the mover 20 . Further, the plate spring 40 has an engagement hole 45 that engages with the protrusion 26 of the mover 20, and a lower surface of the base portion 41 that is the bottom surface of the recess 25 of the mover 20, i.e., an upper surface 201 (mover side) of the mover 20. spring receiving surface). The outward folded portion 44 of the plate spring 40 is formed by the upper piece 51 of the cover 50 facing the upper surface 201 of the mover 20 when the cover 50 is attached to the assembly, specifically the stator 10, as shown in FIG. is pressed against the lower surface 501 (cover-side spring receiving surface) of the . In this manner, the base portion 41 of the leaf spring 40 is in pressure contact with the upper surface 201 of the mover 20, and the left and right outward folded portions 44 are in pressure contact with the lower surface 501 of the upper piece 51 of the cover 50, whereby the mover 20 is It is urged downward, ie, toward the stator 10 by a leaf spring 40 . Since the leaf spring 40 is held in a fixed position even when the slider 20 vibrates due to the engagement between the engagement hole 45 and the protrusion 26 of the slider 40, a stable biasing force is applied to the slider 20. can. In FIGS. 5 and 6, the solid line indicates the state in which the outward folded portion 44 of the leaf spring 40 is in pressure contact with the lower surface 501 of the upper piece 51 of the cover 50, and the state before the cover 50 is attached to the assembly. The two-dot chain line indicates the state of no load.

4 to 8 show a state in which the wire 30 is not energized. In this state, the moving element 20 is pressed toward the stator 10 by the biasing force of the plate spring 40, thereby extending the wire 30. The wire 30 is deformed into a wavy shape so as to follow the wavy shape of the upper surface of the stator 10 and the lower surface of the mover 20 . When the wire 30 is energized, the wire 30 contracts due to heat generation, so that the mover 20 is pushed upward against the biasing force of the plate spring 40 . After that, when the electricity to the wire 30 is stopped, the wire 30 is cooled and returns to the state shown in FIG. By repeating energization and non-energization of the wire 30, the mover 20 is vibrated up and down.

As described above, according to the actuator A according to the embodiment of the present invention, the leaf spring 40 can be held by the actuator A by arranging the leaf spring 40 between the mover 20 and the cover 50. It can be easily assembled without providing. Further, in the actuator A, since one leaf spring 40 can press the mover 20, a plurality of leaf springs are not required. Therefore, it is possible to suppress the increase in size of the actuator A, and it is possible to reduce the number of parts and the number of assembly man-hours.

Further, the cover 50 can be easily formed by sheet metal press molding or the like. By forming the cover 50 as a metal press-molded product, the cover 50 can be formed thinner than in the case where it is formed of a resin part, and the actuator A can be miniaturized. In addition, since the leaf spring 40 is provided independently of the cover 50 and the mover 20 in the actuator A, the strength of the biasing force of the leaf spring 40 can be adjusted by changing the thickness and shape of the leaf spring 40. is.

In the actuator A, the cover 50 covers the opposing portions of the stator 10 and the moving element, that is, the gap between the wavy portion of the stator 10 and the wavy portion of the moving element 20 where the wires 30 are interposed. As a result, it is possible to prevent the wire 30 from falling off from the assembly and foreign matter from entering the gap from the outside. Moreover, since the internal parts (stator, mover, wire 30, etc.) are protected by the cover 50, contact with the internal parts from the outside can be prevented, and the handleability of the actuator A is improved. Furthermore, since both sides of the assembly are covered with the cover 50, the X-direction movement between the stator 10 and the mover 20 can be restricted, and the Z-direction movement of the mover 20 with respect to the stator 10 can be restricted. I can guide you smoothly. Therefore, the product reliability of the actuator A, that is, long-term use stability can be improved.

In the actuator A, the biasing member is a plate whose intermediate base portion 41 is in pressure contact with the upper surface 201 of the mover 20 and whose outward folded portions 44 at both end portions are in pressure contact with the lower surface 501 of the cover 50 facing the upper surface 201 . Since the spring 40 is used, the configuration of the urging member can be simplified, and can be easily manufactured.

Although the description of one embodiment of the present invention is finished above, aspects of the present invention are not limited to this embodiment.

For example, the following modifications are possible without departing from the scope of the invention.
(1) The urging member is not only the leaf spring 40 but also a compression coil spring, a torsion coil spring, an air or liquid spring in which gas or liquid is enclosed in a sealed bag, or an elastic body such as rubber.
(2) Instead of the wire 30, a shape memory alloy having a strip shape or other shape is used.
(3) The left and right end faces of the cover 50 are closed, and the cover 50 is shaped like a box with only the bottom end open. This can more reliably prevent foreign matter from entering the cover 50 .
(4) The leaf spring 40 is a leaf spring whose intermediate portion is in pressure contact with the lower surface of the upper piece 51 of the cover 50 and whose side portions are in pressure contact with the upper surface of the mover 20 .
(5) In the above (4), one of the upper piece 51 of the cover 50 and the intermediate portion of the leaf spring is provided with a positioning projection, and the other is similarly engaged with the projection for positioning. Make a hole.
(6) A downward projection is provided in the intermediate portion of the plate spring 40, and a positioning engagement recess is provided in the bottom surface of the recess in the moving element 20, with which the projection engages.

A Actuator 1, 10 Stator 2, 20 Mover 3, 30 Wire 11 Base member 11a Mounting piece 12 Stator main body 14, 15 Rivet 16 Stator side depression 16a Bottom surface 16b Stator side protrusion 17 Stator side protrusion 17a top surface 17b stator-side groove 21 slider-side recess 21a bottom surface 21b slider-side projecting piece 22 slider-side projection 22a top surface 22b slider-side groove 25 recess 26 projection 27 rib 40 leaf spring (biasing member )
41 base portion 42 inward folded portion 43 curved portion 44 outward folded portion 45 engagement hole 50 cover 51 upper piece 52 side piece

Claims (8)

a stator;
a moving element that faces the stator and is provided so as to be able to approach and move away from the stator;
a shrinkable wire made of a shape memory alloy disposed between the mover and the stator;
a cover fixed to the stator and covering the mover;
a biasing member disposed between the mover and the cover to bias the mover toward the stator;
An actuator comprising: 2. The urging member according to claim 1, wherein the biasing member is a leaf spring having a middle portion pressed against one of the mover and the cover and both side portions pressed against the other of the mover and the cover. actuator. The leaf spring is
an inwardly folded portion folded inwardly from both ends in the longitudinal direction of the base;
an outwardly folded portion outwardly folded back from an inner end of the inwardly folded portion;
3. The actuator of claim 2, comprising: 4. The actuator according to claim 2, wherein the leaf spring is provided with an engaging hole, and the moving element is provided with a positioning projection that engages with the engaging hole. 5. The actuator according to any one of claims 1 to 4, wherein the cover covers the facing portion between the stator and the mover. 6. The actuator according to any one of claims 1 to 5, wherein the cover restricts lateral movement of the mover. 7. The actuator according to any one of claims 1 to 6, wherein the cover is open on the stator side. The actuator according to any one of claims 1 to 7, wherein the cover is a press-molded product.

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