JP2009296862A - Piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load to a piezoelectric element for being displaced so as not to weight a working piece controlled by the piezoelectric element as much as possible. <P>SOLUTION: A piezoelectric actuator incorporates a plunger, a spring member always energizing the plunger so as to project a tip portion of the plunger from an opening of a box, a piezoelectric element to convert a voltage signal into a mechanical displacement, and a working piece to be connected to the piezoelectric element and to disengage the plunger by control of the piezoelectric element in the box. In the piezoelectric actuator, the working piece disengages the plunger by sliding an inner face of a bottom wall of the box toward a horizontal direction, the piezoelectric element connects one end portion thereof to a first piezoelectric element and one end portion of the first piezoelectric element and includes a second piezoelectric element for being extratensively displaced from a free end portion side, and a base end portion of the first piezoelectric element is supported at a box side. Meanwhile, the working piece is engaged with the free end portion of a second piezoelectric element piece. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator, and more particularly to a piezoelectric actuator for an electrically controllable clutch device in a mechanical drive mechanism.

  Patent Document 1 requires an exclusive right for an electrically controlled latch mechanism regardless of the technical field, and the latch mechanism is “a hollow plunger (hollow operating rod) provided in a box so as to be reciprocally movable”. A long piezoelectric element is arranged in the longitudinal direction of the hollow actuating rod, and the base end of the long piezoelectric element is sandwiched between two hollow actuating rods so that it is horizontal from the base end. The free end of the piezoelectric element extending in the direction of the piezoelectric element faces the receiving leg that extends inside the hollow working rod of the engagement piece (engagement piece referred to as a claw) that is pivotally supported by the box. When a voltage signal is applied through the wire, the free end portion of the piezoelectric element is displaced and presses the receiving leg portion of the engagement piece, whereby the engagement piece has its support shaft as one fulcrum, The engagement tip portion is separated from the inclined notch groove formed on the outer surface of the hollow operating rod ".

  In addition to Patent Document 1, Patent Document 1 describes that (a) a long piezoelectric element is housed in a state where one end portion is fixed in a hollow working rod, and (a) a lead wire that is not shown in the drawing is hollow. (C) A horizontal T-shaped engagement piece extends inside the hollow working rod so that its receiving leg faces the free end of the piezoelectric element. In addition, it can be recognized that the engagement tip portion intersecting with the receiving leg portion is characterized in that it is engaged with and disengaged from the outer surface inclined notch groove of the hollow operating rod.

  However, the electric control type latch mechanism described in Patent Document 1 has a piezoelectric element built in a state of being sandwiched by a hollow operating rod, and a leg portion of an engagement piece called a claw is extended to the vicinity of the free end of the piezoelectric element. In order to make it exist, there was a problem that the hollow working piece had to be configured in a complicated manner.

  In addition, there is a disadvantage that the number of parts is too large.

  Here, terms such as applying a voltage, giving an electrical signal, giving a drive signal, and the like are legally interpreted from the essential viewpoint of the invention.

Terms such as voltage application, electric signal application, drive signal application, etc. have the same meaning.
Special table 2006-519465 gazette

  An intended object of the present invention is not to directly apply the weight of an operating piece (a plunger locking piece) that cooperates with the piezoelectric element to the piezoelectric element. In other words, the load on the displaceable piezoelectric element is reduced so as not to apply the weight of the operation piece controlled by the piezoelectric element as much as possible. The second purpose is to effectively use the internal space of the box. The third object is that a long piezoelectric element, an operating piece having a lock function, a plunger and a spring member can be easily assembled in the internal space of the box. A fourth object is that a long piezoelectric element (actuator) having a large displacement can be mounted. The fifth object is to enable the plunger to reliably engage and disengage the operating piece that cooperates with the long piezoelectric element having a large displacement.

  The piezoelectric actuator of the present invention converts a plunger into a box, a spring member that constantly urges the plunger so that the tip of the plunger protrudes from the opening of the box, and a voltage signal into a mechanical displacement. Piezoelectric actuators each incorporating a piezoelectric element and an operating piece that is connected to the piezoelectric element and that engages and disengages from the plunger under the control of the piezoelectric element, wherein the operating piece covers the inner surface of the bottom wall of the box. Slides horizontally to engage / disengage from the plunger, and the piezoelectric element is coupled to one end of the first piezoelectric element and one end of the first piezoelectric element, and can be expanded outward from the free end side. A second piezoelectric element, and a base end portion of the first piezoelectric element is supported on the box body side, while the operating piece is engaged with a free end portion of the second piezoelectric element piece. To feature And butterflies.

  Further, the piezoelectric actuator of the present invention includes a plunger in the box, a spring member that constantly biases the plunger so that the tip of the plunger protrudes from the opening of the box, and a mechanical displacement of the voltage signal. Piezoelectric actuators each incorporating a piezoelectric element to be converted and an operating piece connected to and disengaged from the plunger by control of the piezoelectric element, the operating piece being a free end of the piezoelectric element The inner surface of the bottom wall of the box body is slid in the horizontal direction and the plunger is locked when energized.

(A) In the invention according to claim 1 or 5, the operating piece engages with the free end of the piezoelectric element, and when energized, the inner surface of the bottom wall of the box is slid horizontally to engage the plunger. Therefore, the intended purpose of the present invention can be achieved.
(B) Since the piezoelectric element is positioned outside the plunger, the internal space in the box can be used effectively, and the members can be easily combined. For example, by mounting a large elongated piezoelectric element, the operating piece can be reliably engaged with and disengaged from the plunger.

The best mode for carrying out the present invention shown in FIGS. 1 to 11 will be described below (first embodiment).
(1) Environment for Implementing the Invention FIG. 1 is a schematic explanatory view showing a piezoelectric actuator X. FIG. The piezoelectric actuator X is used for, for example, an electrically controllable clutch device in a mechanical drive mechanism. Therefore, an example of the application is the same as that of Patent Document 1. FIG. 1 shows the internal structure of the box 1. In addition, the code | symbol Y is a door frame, for example.
(2) Box 1
FIG. 1 is a perspective view of main members incorporated in a vertically long box 1, and a case lid, a right side wall, a substrate and the like are omitted. FIG. 2 is an explanatory view from a front view with a part of the case lid 1b cut away, FIG. 3 is a schematic explanatory view showing the structure of the case body 1a, and FIG. It is explanatory drawing.

  The box 1 includes a case body 1a and a case lid 1b united with the case body. Therefore, it is the same structure as a lock box. For example, referring to FIG. 3, reference numerals 2 and 3 denote upper and lower walls, and an opening 4 for the plunger 41 is formed at one end portion (left end portion) of the upper wall 2. Reference numerals 5 and 6 denote left and right side walls.

  Thus, a plurality of guide means for the plunger 41 are provided inside the box body 1. That is, 7 is a first guide wall facing the bottom wall 3 with a predetermined space, and 8 is provided at the center of the box 1 so as to face the opening 4 of the front wall 2 and the first guide wall 7. The second horizontal guide wall is formed with an unnumbered through hole (guide hole) at the center of the horizontal guide walls 7 and 8 so that the sliding shaft 42 of the plunger 41 can be guided. Yes.

  On the other hand, the first and second vertical guides 9 and 10 extend from the inner wall surface of the front wall 2 toward the bottom wall 3 so as to be orthogonal to the front wall 2 and guide the latch portion 43 of the plunger 41. It is a guide wall.

A support member 11 that supports the base end portion 21 a of the long piezoelectric element 21 is provided inside the box body 1. In the present embodiment, the piezoelectric element 21 is disposed vertically along the inner wall surface of the right side wall 6, so that it is formed on the lower side of the right side wall 6 or the right inner wall surface of the bottom wall 3 as shown in FIG. It is fixed. The support member 11 is formed, for example, in an upward U shape, and the base end portion 21 a of the piezoelectric element 21 is inserted into and engaged with the vertical groove 11 a of the support member 11.
(3) Members to be incorporated in the box 1 As shown in FIG. 2, the box 1 has a board 15 having a booster circuit, and a long shape electrically connected to the board 15 via the lead wires 16. The piezoelectric element 21, the operation piece 31 having a locking function, the plunger 41 that is guided by a plurality of guide means and moves back and forth in the vertical direction, and the tip portion (latch portion) 43 of the plunger 41 protrudes from the opening 4 of the box 1. Thus, a spring member 47 that constantly biases the plunger is incorporated.

In this embodiment, the substrate 15 is appropriately fixed to the inner wall surface of the right side wall 6 and is controlled by the control unit 14 disposed outside the box 1 as shown in FIG.
(4) Piezoelectric element 21
As shown in FIGS. 1 and 2, the long piezoelectric element 21 is a single plate type or two plate type (this embodiment) long plate disposed along the inner surface of one side wall 6 of the box 1. The base end portion 21a of the body is supported by the support member 11 provided on the bottom wall 3 side, while the free end portion 21b facing the base end portion 21a horizontally covers the inner wall surface of the bottom wall 3. It is inserted and engaged with the engaging portion 32 of the operating piece 31 that slides in the direction (see FIGS. 2 and 5).

  Now, the long piezoelectric element 21 of the present embodiment is a double structure 21A, 21B as shown in FIG. That is, the piezoelectric element 21 has a first piezoelectric element 21A having a base end portion 21a and one end portion coupled to one end portion of the first piezoelectric element, and extends outwardly so as to warp from the free end portion 21b side. The base end portion 21a of the first piezoelectric element is slightly longer than the free end portion 21b (see FIG. 5).

  In such a long piezoelectric element 21 of the double structures 21A and 21B, the base end portion 21a of the first piezoelectric element 21A is fixedly supported by the vertical groove 11a of the support member 11. The free end portion 21b of the second piezoelectric element 21B is also moved to the lower end of the sliding shaft 42 at the same time as the coupling end portion 21c side corresponding to the central portion is displaced so as to warp toward the upper end portion side of the sliding shaft 42 of the plunger 41. Since it is displaced so as to warp in the part side direction, the width (displacement amount) by which the operating piece 31 moves left and right is increased (see FIGS. 10 and 2). Therefore, the advantage is that the long piezoelectric element 21 having a large displacement amount is mounted in the internal space of the box body 1 and the operating piece 31 that cooperates with the long piezoelectric element can be reliably engaged with and disengaged from the plunger 41. There is.

  Further, the base end portion of the long piezoelectric element 21 can be easily fixed in the box 1.

  By the way, although the piezoelectric element 21 looks like one end portion of two long plates joined together, it is a multilayer structure as shown in FIG. 7, and a voltage signal applied from the substrate 15 having a booster circuit. To mechanical displacement. Here, the basic configuration and function of the piezoelectric element 21 will be described with reference to FIG. The piezoelectric element 21 is a rectangular plate-like body having a multilayer structure including a piezoelectric body. For example, a central plate 22 and a pair of piezoelectric plates laminated on both surfaces of the central plate 22 with a conductive adhesive layer 23 interposed therebetween. 24.

  Thus, the central plate 22 is a reinforcing material having conductivity on the surface, and a material obtained by quenching SK steel is used. The piezoelectric plate 24 includes an unnumbered piezoelectric body and a pair of electrodes 25 stacked on both surfaces of the piezoelectric body. The piezoelectric body of the piezoelectric plate 24 is not particularly limited as long as it is a material having a piezo effect that causes distortion when voltage is applied. For example, piezoelectric ceramics, polymer piezoelectric bodies, single crystal piezoelectric bodies, and the like are used. Among these, piezoelectric titanate / zirconate-based piezoelectric ceramics (PZT) having a large piezoelectric effect and good durability are used.

  Moreover, the electrode 25 is laminated | stacked on the substantially whole surface except the outer edge part of a piezoelectric material, for example, is formed by printing and baking of a silver paste.

  The piezoelectric element 21 includes a pair of electrodes 25 and a central plate 22 arranged on the outer surface side, for example, from a driving unit (drive) of the substrate 15 in the lock box via the control unit 14 arranged outside. A drive (voltage) signal is applied. In this embodiment, as shown in FIG. 2, the lead wire 16 is electrically connected to the substrate 15, and even if the plunger 41 moves, the lead wire 16 itself does not move at all. The substrate 15 alternately applies a positive voltage and a negative voltage to both outer electrodes 25 via the lead wires 16.

When a positive voltage is applied in this way, one piezoelectric body expands, while the other piezoelectric body contracts. As a result, the piezoelectric element 21 curves to one side. Here, the function of the piezoelectric element 21 is expressed as “converting a voltage signal into a mechanical displacement”. As for the voltage effect, as described above, in addition to the bimorph structure having the voltage plate 24 on both sides, a unimorph structure having the voltage plate 24 only on one side is known as a known matter.
(5) Working piece 31
FIG. 8 is a perspective view of the operating piece 31 having a locking function. The working piece 31 of this embodiment is formed in a block shape (for example, a rectangular parallelepiped) having a rectangular bottom surface 31a and top surface 31b. The block-shaped operating piece 31 is incorporated in a predetermined space between the bottom wall 3 and the first guide wall 7 and slides on the inner wall surface of the bottom wall 3 in the left-right direction while being controlled by the piezoelectric element 21. In addition, the operating piece 31 of the present embodiment is connected to the free end 21 b of the piezoelectric element 21 and enters the lower end surface of the sliding shaft 42 of the plunger 41 while cooperating with the piezoelectric element 21.

Therefore, the operating piece 31 has a concave engaging portion 32 at one end portion on the support member side in order to connect the free end portion 21 b of the piezoelectric element 21. In addition, spherical sliding small protrusions 33 are provided on the bottom surface 31a and the top surface 31b in order to improve the sliding of the operating piece 31.
(6) Plunger 41 and biasing spring 47,
FIG. 9 is a perspective view of the plunger 41 having a latch function. The plunger 41 of the present embodiment is composed of a sliding shaft 42 guided by the first and second horizontal guide walls 7 and 8 and a latch portion 43 connected to the upper end of the sliding shaft 42. A flange portion 44 that is received by the second horizontal guide wall 8 is provided at the center of the sliding shaft 42.

  The urging spring 47 is wound around the sliding shaft 42 so as to be in pressure contact with the rear end surface (lower end surface) of the latch portion 43 and the second horizontal guide wall 8, and the triangular latch portion 43 of the plunger is provided. The plunger is always urged so as to protrude from the opening 4 of the box 1. In addition, although the front-end | tip part 43 of the plunger 41 is formed in the triangle in a present Example, this is an arbitrary matter, and the locking surface which has a locking function, and the inclined surface which has a sliding contact function are made into a right triangle. You can also

(7) Operation In FIG. 2, it is assumed that there is a fixed body (for example, a door frame) Y that faces the upper wall (front wall) 2 of the box 1 of the piezoelectric actuator X. Of course, Y may be the movable side, and the box 1 of the piezoelectric actuator X may be the fixed side. The plunger 41 is always urged by a spring member 47 so that the tip end portion 43 projects from the opening 4. Therefore, the case of non-energization and energization will be described. FIG. 11 shows a case where no power is supplied. When no voltage is applied to the piezoelectric element 21 (when no current is applied), the piezoelectric element 21 is in a parallel state (substantially vertical state) to the inner wall surface of the right side wall 6 of the box 1. In addition, the operating piece 31 is pulled back toward the support member 11 while sliding on the inner wall surface of the bottom wall 3 at the free end portion 21b of the piezoelectric element 21, and the engaged portion of the plunger 41 (in this embodiment, the sliding shaft) Move away from the bottom edge (unlocked). Therefore, the plunger 41 can be retracted into the box 1 against the spring force of the spring member 47 as indicated by an arrow.

  On the other hand, FIG.1 and FIG.2 is a case at the time of electricity supply. When a voltage is applied to the piezoelectric element 21, the piezoelectric element 21 converts the voltage signal into a mechanical displacement, so that the coupling end 21 c side and the free end 21 b side slide on the plunger 41 as described above. The position is displaced so as to warp toward the shaft 42 side.

  Therefore, the operating piece 31 moves away from the support member 11 side while sliding on the inner wall surface of the bottom wall 3 and enters the lower end surface of the sliding shaft 42 (locked state). Therefore, the plunger 41 cannot be retracted. In this way, the piezoelectric element 21 controls the plunger 41 in the unlocked state or the locked state by sliding the operating piece 31 left and right along the inner wall surface of the bottom wall 3 at its free end 21b (see FIG. 10). .

Next, a second embodiment of the present invention will be described. In the description of the second embodiment, the same parts as those in the first embodiment are denoted by the same or similar reference numerals, and redundant description is omitted.

12 to 16 are explanatory views of the second embodiment. In the piezoelectric actuator X1 of the second embodiment, although the location of the long piezoelectric element 21, the operating piece 31A, the support member 11, the substrate 15 and the like is different, the main differences from the first embodiment are as follows. It is as follows.
(A) The plunger 41 of the first embodiment protrudes from the opening 4 of the upper wall 2 of the lock box 1, whereas the plunger 41A of the first embodiment is the lower end of the right side wall 6 of the box 1A. It protrudes from the opening 4A formed in. When comparing the configurations of the plungers 41 and 41A, the former 41 has the sliding shaft 42, whereas the latter does not have the sliding shaft 42. Thus, as shown in FIG. 13, the front wall 41a on the near side of the plunger 41A is formed in the shape of an arrow mark plate, and is formed in a rectangular cross section up to the rear wall 41b on the far side (see FIG. 14). Further, a protrusion-like latch engaged portion 45 is formed at an appropriate location on the back wall 41b of the plunger 41A.
(B) Therefore, the plunger 41A of the second embodiment is against the spring force of the spring member 47 interposed between the rear end portion and the left side wall 5 of the lock box 1A, and the inner wall surface of the bottom wall 3 And can be moved backward in the horizontal direction while being restricted by the first horizontal guide plate 7A.
(C) When energized, the working piece 31 of the first embodiment enters below the plunger 41 and prevents the plunger 41 from retreating, whereas the working piece 31A of the second embodiment has the case body 1a. The inner wall surface of the bottom wall 3 is slid from one wide side wall to the case lid 1b side while engaging the latch engaged portion 45 of the plunger 41A to prevent the plunger 41A from retreating.
(D) Furthermore, the guide means in the lock box 1A is only the first horizontal guide plate 7A facing the bottom wall 3. The substrate 15 is attached in a vertical state via a partition-like support plate 48 provided in the lock box 1A. The explanation of other detailed differences is omitted.

  By the way, the piezoelectric element 21 of the first and second embodiments is of a double structure 21A, 21B (two-sheet type with one end connected), and is open to the public that can be accessed by the public via a telecommunication line. According to the information, it is called “bimorph”.

  According to general public information, the bimorph is a general term for piezoelectric actuators in which voltage ceramics are attached to both the front and back sides of the central base plate, that is, two piezoelectric ceramics. . Therefore, as long as the piezoelectric element 21 of the first and second embodiments is configured to use two voltage ceramics, it may be a single-sheet type structure.

  Further, according to the general public information, there is a piezoelectric element called “unimorph”. FIG. 17 is a schematic explanatory diagram showing a specific configuration of a unimorph. As is apparent from FIG. 17, the piezoelectric element 21 having a unimorph structure basically has a structure in which one voltage ceramic is attached to one side of one metal plate. For example, one unimorph, two sheets Unimorph exists.

  However, the piezoelectric element 21 of the first and second embodiments may employ a single unimorph. Here, just in case, in order to confirm that another embodiment adopting a unimorph is also within the range of the range of the present invention, an example is shown in FIG.

  In FIG. 18, the piezoelectric element 21 is a “single-sheet type structure” and “one unimorph”. In the case where the piezoelectric element 21 is a single-sheet structure, the support member 11 that supports the free end 21 a is fixed to the inner wall surface side of the upper wall 2. Thus, the piezoelectric element 21 of the present invention can be used as either “bimorph” or “unimorph” without departing from the object of the invention.

  Furthermore, the application of the piezoelectric actuator X of the present invention is not limited to the clutch mechanism for electrical control, but can be used for a latch mechanism or a lock mechanism for joinery. When the piezoelectric actuator X is used for joinery, it can be attached to a shutter or movable shoji that moves in the vertical direction, or a door that rotates in the horizontal direction.

  In the present embodiment, at least the drive unit is provided on the substrate 15, but it is needless to say that the control unit 14 may be provided together with the drive unit.

  The present invention is mainly used in the joinery and lock industry.

1 to 11 are explanatory views showing the best embodiment (first embodiment) of the present invention. 12 to 16 are explanatory views showing the best embodiment (second embodiment) of the present invention.
The perspective view of the internal structure of the piezoelectric actuator of 1st Example (at the time of electricity supply, a locked state). Schematic explanatory drawing (reference diagram, locked state) showing the internal structure of the piezoelectric actuator. The schematic explanatory drawing which shows the structure of a case body. FIG. 4 is a schematic cross-sectional explanatory diagram based on line 4-4 in FIG. 2; The schematic explanatory drawing of the principal part. The perspective view which shows an example of a piezoelectric element. Schematic explanatory drawing which shows the specific structure of a piezoelectric element. The perspective view which shows the structure of an action | operation piece. The perspective view which shows the structure of a plunger. Schematic explanatory drawing from the non-energized state (unlocked state) to the energized state (locked state). Explanatory drawing at the time of non-energization (unlocked state). The perspective view of the internal structure of the piezoelectric actuator of 2nd Example (at the time of electricity supply, a locked state). The schematic explanatory drawing which shows the internal structure of a piezoelectric actuator (same figure as FIG. 2). FIG. 14 is a schematic cross-sectional explanatory diagram based on the line 14-14 in FIG. 13. Schematic explanatory drawing of the main part (similar to FIG. 10). The perspective view of the internal structure of a piezoelectric actuator (same figure as FIG. 11). Schematic explanatory drawing which shows the other example (unimorph structure) of a piezoelectric element. The schematic explanatory drawing similar to FIG. 2 in the case of using a unimorph.

Explanation of symbols

X, X1 ... piezoelectric actuator, Y ... fixed side (or movable side), 1, 1A ... box, 1a ... case body, 1b ... case lid, 2 ... top wall, 3 ... bottom wall, 4A ... opening, 5, 6 ... Left and right side walls, 7, 7A ... First horizontal guide wall, 11 ... Support member, 14 ... Control part, 15 ... Substrate, 16 ... Lead wire, 21 ... Piezoelectric element, 21A ... First piezoelectric element, 21B ... 2nd piezoelectric element, 21a ... Base end part, 21b ... Free end part, 21c ... Coupling end part, 31, 31A ... Actuating piece, 32 ... Engagement part, 33 ... Sliding small protrusion, 41, 41A ... Plunger, 41a ... Front wall, 41b ... Back wall, 42 ... Sliding shaft, 43 ... Latch part (tip part), 44 ... Flange part, 45 ... Latch engaged part, 47 ... Spring member, 48 ... Partition-like support plate .

Claims (5)

Inside the box, a plunger, a spring member that constantly biases the plunger so that the tip of the plunger protrudes from the opening of the box, a piezoelectric element that converts a voltage signal into a mechanical displacement, and the piezoelectric element Piezoelectric actuators each incorporating an operating piece connected to and disengaged from the plunger by control of the piezoelectric element, wherein the operating piece slides horizontally on the inner surface of the bottom wall of the box. The piezoelectric element includes a first piezoelectric element and a second piezoelectric element that is coupled to one end of the first piezoelectric element and has a second piezoelectric element that can be displaced outwardly from the free end side. And the base end part of the said 1st piezoelectric element is supported by the box side, On the other hand, the said operation piece is engaging with the free end part of the said 2nd piezoelectric element piece, The piezoelectric actuator characterized by the above-mentioned. The piezoelectric actuator according to claim 1, wherein a substrate having a booster circuit is provided in the box. 2. The piezoelectric actuator according to claim 1, wherein, when energized, the operating piece enters below the plunger and prevents the plunger from moving backward. 2. The piezoelectric actuator according to claim 1, wherein, when energized, the operating piece engages with a latch engaged portion of the plunger to prevent the plunger from moving backward. Inside the box, a plunger, a spring member that constantly biases the plunger so that the tip of the plunger protrudes from the opening of the box, a piezoelectric element that converts a voltage signal into a mechanical displacement, and the piezoelectric element And a piezoelectric actuator that incorporates an operating piece that engages with and disengages from the plunger under the control of the piezoelectric element, wherein the operating piece engages with a free end of the piezoelectric element, A piezoelectric actuator, wherein an inner surface of a bottom wall of a box is slid horizontally to lock the plunger.

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