JPH02192182A - Piezoelectric element - Google Patents

Abstract

PURPOSE:To easily and surely perform an electrically connecting operation of electrodes by a method wherein conductive adhesive agents interposed between piezoelectric element pieces are electrically connected with each other through the intermediary of the extending parts of the adhesive agent and a lead-out conductive adhesive agent of a peripheral face. CONSTITUTION:Conductive adhesive agent such as silver paste or the like is applied to the sides of piezoelectric element pieces q1-qn providing specified spaces pr from the outer- peripheral edges of the piezoelectric element pieces q1-qn to form adhesive parts pa between piezoelectric element pieces q1-qn, and conductive adhesive agent is applied between the outer-peripheral edge of the adhesive part pa and the outer circumference of the piezoelectric element pieces q1-qn to form an extending part pb. The piezoelectric element pieces q1-qn are laminated making the extending parts pb of the conductive adhesive agent face each other, and the piezoelectric element pieces q1-qn are laminated on a substrate r to which conductive adhesive agent is applied and pressure-bonded together to constitute a piezoelectric element Q of integral structure, lead-out conductive adhesive agent pc is applied in a specified width in an axial direction onto the outer circumferential face of the laminated piezoelectric element pieces q1-qn and connected to the outside end of the extending part pb applied onto the outer circumference of the piezoelectric element pieces q1-qn. As mentioned above, the conductive adhesive agents interposed between the piezoelectric element pieces q1-qn are made to serve as electrodes, whereby the electrodes are easily, surely, and electrically connected with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a piezoelectric element used in a piezoelectric actuator or the like.

(B) Conventional technology Conventionally, as a form of piezoelectric actuator, a piezoelectric actuator has been developed by using a plunger that moves in the axial direction, a clamp member that grips the plunger, a piezoelectric element that operates the clamp member, and a stroke piezoelectric element that moves the plunger. Each piezoelectric element is constructed by laminating and bonding a plurality of piezoelectric element pieces with a conductive adhesive such as silver paste to form one piezoelectric element, and the conductive adhesive is used as an electrode. In order to connect the same electrode to a drive circuit etc., as shown in Fig. 10,
When piezoelectric element pieces are laminated and bonded, a small piece of silver foil or the like is inserted between each piezoelectric element piece and adhered with a conductive adhesive, and a thin copper wire is hung on this.

(c) Problems to be Solved by the Invention However, it is extremely time-consuming to solder thin #I wires to the electrodes between many pieces of piezoelectric elements, and the strength of thin copper wires is low. There was a drawback that the silver foil or A[[I copper wire could be cut or short-circuited during handling of the device.

(d) Means for Solving the Problems In the present invention, in a piezoelectric element stacked with a conductive adhesive interposed between a plurality of piezoelectric element pieces, each piezoelectric element is formed at a predetermined interval from the outer periphery of the piezoelectric element. Apply a conductive adhesive extending from the adhesive part to the outer periphery of the piezoelectric element piece, and apply the conductive adhesive to the outer periphery of the piezoelectric element after lamination (by applying the conductive adhesive for knee bonding). It is an object of the present invention to provide a piezoelectric element in which conductive adhesive interposed between each piezoelectric element piece is electrically connected through a lead-out part and a conductive adhesive for drawing out.

(e) Functions and Effects In the present invention, to connect the electrodes, the thin copper wire is eliminated, and each electrode is connected and conductive using a conductive adhesive that extends outside the adhesive surface of each piezoelectric element and is applied. This has the effect of simplifying the electrode conduction work without requiring the troublesome work of soldering, and preventing conduction from breaking or short-circuiting while handling the piezoelectric element. There is.

(F) Embodiment FIGS. 1 and 2 show embodiments of the present invention, each of which has a substantially ring-shaped piezoelectric element piece (q1) having a predetermined thickness.
(qn) and a substrate (r) are laminated and bonded to form an integrated piezoelectric element (Q).

As shown in FIG. 2, silver is placed on both sides of each piezoelectric element piece (q1) to (qn) at a predetermined interval (p r ) from the outer periphery of each piezoelectric element piece (q1) to (qn). A conductive adhesive such as paste is applied using a method such as screen printing to form a bonded area (pa) between each piezoelectric element piece (q1) to (qn).
It is said that

Then, an extending portion (pb) of conductive adhesive is applied from the outer periphery of the adhesive portion (pa) to the outer periphery of the piezoelectric element pieces (q1) to (qn).

Note that the extending portion (pb) is connected to each piezoelectric element piece (ql) to (
Although it is applied to both sides of an), the front and back surfaces are located at opposite sides.

Then, the extending parts [pb] of the conductive adhesive are stacked so as to face each other, and these piezoelectric element pieces (q1) to (qn) are stacked on the substrate (r) coated with the conductive adhesive, The piezoelectric element (Q) is bonded under pressure to form an integrated piezoelectric element (Q), and a conductive adhesive (PC) for drawing out with a predetermined width in the axial direction is applied to the outer peripheral surface of the laminated piezoelectric element pieces (ql) to (on). The extended portion (p) coated to the outer periphery of each piezoelectric element piece (q1) to (qn)
The outer edge of b) is #pillared.

In the piezoelectric element (0) that is laminated and bonded together in this way, the conductive adhesive interposed between the piezoelectric element pieces (q1) to (qn) can be used as electrodes, and each electrode is The extension part of the adhesive (pb) and the conductive adhesive for drawer (p
It is electrically connected to the terminal (W) of the substrate (r) via the terminal (W) and the terminal (W) of the substrate (r).

In addition, the extension part (pb) is formed by a method such as screen printing.
The conductive adhesive for the adhesive part (pa) can be applied to the piezoelectric element pieces (ql) to [+n) at the same time as the conductive adhesive for the adhesive part (pa), and the conductive adhesive for drawing out ( pc)
Since the electrodes can be made conductive by simply applying , no soldering work is required and the work is simplified.

Note that the electrodes between each piezoelectric element piece (q1) to (qn) are stacked with the conductive adhesive extensions (pb) facing each other, so that every other electrode is connected to one terminal (W). The electrodes are connected in parallel, and the remaining electrode is connected to the other terminal (W
).

The material of each piezoelectric element piece (q1) to (qn) is, for example, a ferroelectric material having an ABO3 perovskite type crystal structure, and is PZT [:Pb (Zr, T'i).
03] system, PLZT CPb, La < Zr, Ti
)03] system, PTCPbTiO3] system, or PZT
A three-component piezoelectric ceramic based on the above can be used.

Furthermore, although it is possible to use a glass epoxy substrate etc. for the substrate (r), in this example, a ceramic substrate with excellent heat resistance and mechanical strength is used, and silver paste is used as the conductive adhesive. Then, the laminated piezoelectric element pieces (ql) to (a
The piezoelectric element pieces (q1) to (qn) and the substrate fr) are bonded by baking at approximately 800°C while applying pressure to form an integrated piezoelectric element (Q). In addition to increasing strength, the silver particles in the silver paste are welded together to increase conductivity.

Next, a piezoelectric actuator (A) using piezoelectric elements having the product N configured as described above will be described.

As shown in Fig. 3, a plunger (P) is disposed concentrically within a cylindrical case having front and rear walls (a) and (b) and can move forward and backward along the axis. A pair of clamping piezoelectric elements (eHf) each having a clamping member (k) (1) and a stroke piezoelectric element (g) are arranged on the outer periphery of (P).

That is, the piezoelectric element for clamping (e) is arranged and supported under the holder (11) set in the center of the case, while the piezoelectric element for clamping (f) and the piezoelectric element for stroke The piezoelectric element (q) is placed on the upper side of the holder (h).
Supported.

Next, the action of each piezoelectric element (e), (f), and (g) will be explained.

The piezoelectric elements (e) and (f) clamp the plunger (P) via the clamp member (kHl) when a voltage is applied,
When no voltage is applied, the above clamp is released.

On the other hand, the piezoelectric element ((+) shortens in the axial direction when a voltage is applied, and expands and returns to its original position when the voltage is removed.

FIG. 4 shows a piezoelectric actuator (A) having the above configuration.
It shows the configuration of the control device (C) for controlling the
The control device f(C) is a microprocessor (MPII)
, an input interface (1) connected to a switch (S-) etc. that outputs a drive signal, and an output interface (1) connected to piezoelectric elements (e), (f), and (g) via a drive circuit (D). and a memory (M) that stores a drive program for the piezoelectric elements (e), (f), and (g).

Accordingly, the movement of the plunger (P) by the actuator (^) having such a configuration will be explained with reference to FIGS. 5 to 8.

When a drive signal is input to the control device (C), according to the program, a voltage is applied to the piezoelectric element (f) to clamp the plunger (P), as shown in FIG. ) and remove the plunger (P).
Release the clamp.

Next, as shown in FIG. 6, when a voltage is applied to the piezoelectric element (g) to cause it to contract, the piezoelectric element (g) moves in the direction of the arrow, and as a result, the piezoelectric element (f) engages the clamped plunger. (P) also moves in the direction of the arrow.

Thereafter, as shown in FIG. 7, a voltage is applied to the piezoelectric element (e) to clamp the plunger (P), and then,
Release the voltage applied to the piezoelectric element (f) and release the plunger (P).
Release the clamp.

Then, as shown in FIG. 8, the voltage applied to the piezoelectric element (g) is released and expanded, and only the piezoelectric element (f) is moved in the direction of the arrow, returning to the state shown in FIG. 5.

After that, by repeating the above operation, the plunger (
P) can be moved in a linear manner with a stroke of μm order or sub-μm order, and various devices and machines can be operated precisely.

Figure 9 shows a single automatic valve (V) configured to drive a tire plum-shaped valve body using the piezoelectric actuator (8) of the present invention.
, (10) is a valve box, which has an inlet passage (11) and an outlet passage (11) that are connected to the secondary piping and the secondary piping, respectively.
12). Further, in the valve box (10), a main valve hole (13) is formed between the inflow path (11) and the outflow path (12), and the main valve hole (13) is formed at the upper end opening periphery of the main valve hole (13). A valve seat (14) is formed.

A diaphragm (15), which also serves as a main valve element for opening and closing the main valve hole (13), is disposed on the main valve seat (14) so as to be able to move toward and away from the main valve seat (14).

Above the diaphragm (15) is the tire flamm back chamber (1
6) is formed, and the diaphragm back chamber (16) is formed with an orifice (1
7) and communicates with the inflow channel (11).

(18) is a pilot valve hole bored in the diaphragm (15), which connects the tire flamm back chamber (16) and the outflow path (12).
) are in communication.

Above the pilot valve hole (18), a pilot valve body (19) provided at the lower end of the plunger (P) of the piezoelectric actuator (8) is opposed, and the pilot valve hole (18) is opened by the operation of the piezoelectric actuator (^). open and close.

With the above configuration, the unidirectional valve (V) uses the self-servo action of the tire flam type valve body, and the diaphragm (15
) follows the movement of the plunger CP of the piezoelectric actuator (8) to open and close the main valve seat (14).

(20) is a flange that limits the vertical stroke of the plunger (P), and (21) is a seal with a Y-shaped cross section.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional side view and an exploded perspective view of an embodiment of the present invention, FIG. 3 is a cross-sectional explanatory view of a piezoelectric actuator, and FIG.
The figure is a block diagram showing the configuration of the control device, Figures 5 to 8 are explanatory diagrams of the operation of the same actuator, Figure 9 is a sectional view of an automatic valve constructed using the piezoelectric actuator of the present invention, and Figure 10 is a conventional valve. A perspective view of a piezoelectric element piece. Q) : Piezoelectric element pa) : Adhesive part pb) : Extension part p') : Predetermined interval ') : Substrate ql) ~ (an) : Piezoelectric element piece

Claims (1)

[Claims] 1) In a piezoelectric element (Q) in which a plurality of piezoelectric element pieces (q1) to (qn) are laminated with a conductive adhesive interposed between them,
A predetermined interval (
pr) is applied to the outer peripheral edge of the piezoelectric element piece, and an extended part (pb) of conductive adhesive is applied to the outer peripheral surface of the piezoelectric element (Q) after lamination. Apply a conductive adhesive for drawers (PC) to the extension part (PC).
A piezoelectric element in which conductive adhesive interposed between each piezoelectric element piece (q1) to (qn) is electrically connected through a) and a conductive adhesive for drawing (pc).