JP3070311B2 - Piezoelectric laminate - Google Patents
Piezoelectric laminateInfo
- Publication number
- JP3070311B2 JP3070311B2 JP4335862A JP33586292A JP3070311B2 JP 3070311 B2 JP3070311 B2 JP 3070311B2 JP 4335862 A JP4335862 A JP 4335862A JP 33586292 A JP33586292 A JP 33586292A JP 3070311 B2 JP3070311 B2 JP 3070311B2
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric
- piezoelectric plate
- internal electrodes
- fibers
- internal electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000000835 fiber Substances 0.000 claims description 42
- 239000002245 particle Substances 0.000 claims description 24
- 238000006073 displacement reaction Methods 0.000 description 14
- 239000000919 ceramic Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000010410 layer Substances 0.000 description 6
- 229920000049 Carbon (fiber) Polymers 0.000 description 5
- 239000004917 carbon fiber Substances 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- 239000004744 fabric Substances 0.000 description 5
- 239000011521 glass Substances 0.000 description 5
- 239000003365 glass fiber Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 4
- 230000005684 electric field Effects 0.000 description 4
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000010008 shearing Methods 0.000 description 4
- 229910052709 silver Inorganic materials 0.000 description 4
- 239000004332 silver Substances 0.000 description 4
- 239000002759 woven fabric Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000002950 deficient Effects 0.000 description 3
- 238000010030 laminating Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 238000009941 weaving Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229920006231 aramid fiber Polymers 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は積層型圧電アクチュエー
タ等に利用される圧電積層体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric laminate used for a laminated piezoelectric actuator or the like.
【０００２】[0002]
【従来の技術】近年、各種の機械的駆動素子として、電
磁力を利用したアクチュエータに代わって、チタン酸ジ
ルコン酸鉛（ＰＺＴ）磁器などのセラミックスの圧電効
果を利用した積層型圧電アクチュエータが多用されてい
る。この積層型圧電アクチュエータは発熱が少なく、ま
た小型で高速駆動が可能であり、しかも高精度な電圧−
変位特性を期待できるため、各種の機械的駆動素子とし
て極めて有望である。ただ圧電効果による機械的変位は
本質的に極めて小さいので、大きな変位量を得るために
圧電板と電極とを交互に多重に積層し絶縁保護層で被覆
された構造の圧電積層体として提供されている。2. Description of the Related Art In recent years, instead of actuators utilizing electromagnetic force, multilayer piezoelectric actuators utilizing the piezoelectric effect of ceramics such as lead zirconate titanate (PZT) have been widely used as various mechanical drive elements. ing. This laminated piezoelectric actuator generates less heat, is small in size, can be driven at high speed, and has a highly accurate voltage-
Since the displacement characteristics can be expected, it is extremely promising as various mechanical drive elements. However, since mechanical displacement due to the piezoelectric effect is extremely small in nature, it is provided as a piezoelectric laminate having a structure in which piezoelectric plates and electrodes are alternately and multiplexed and covered with an insulating protective layer in order to obtain a large displacement. I have.
【０００３】例えば、以下のように製造された圧電積層
体よりなる積層型圧電アクチュエータが知られている。
まず、チタン酸ジルコン酸鉛よりなる円板状の圧電板の
表裏両面に、銀ペーストを塗布した後、焼き付けて圧電
板の両面に銀電極を形成する。この銀電極を形成した圧
電板と、ＳＵＳ等の金属板よりなる電極板とを交互に複
数枚積層して積層体とする。この積層体を絶縁保護層で
被覆し、さらに分極処理することにより、圧電板と内部
電極とが交互に積層されて一体化された積層型圧電アク
チュエータとされる。なお上記分極処理は、一般に室温
〜１５０℃の雰囲気中で内部電極を介して圧電素子に所
定の電圧を印加することにより行われる。この積層型圧
電アクチュエータは、上記内部電極への通電により上記
圧電板が軸方向（積層方向）に伸びてアクチュエータと
して作動する。For example, a laminated piezoelectric actuator comprising a piezoelectric laminated body manufactured as follows is known.
First, a silver paste is applied to both front and back surfaces of a disk-shaped piezoelectric plate made of lead zirconate titanate, and then baked to form silver electrodes on both surfaces of the piezoelectric plate. A plurality of piezoelectric plates on which the silver electrodes are formed and electrode plates made of a metal plate such as SUS are alternately laminated to form a laminate. This laminated body is covered with an insulating protective layer and further subjected to a polarization treatment, whereby a laminated piezoelectric actuator is obtained in which piezoelectric plates and internal electrodes are alternately laminated and integrated. Note that the above-mentioned polarization treatment is generally performed by applying a predetermined voltage to the piezoelectric element via an internal electrode in an atmosphere at room temperature to 150 ° C. In the laminated piezoelectric actuator, the piezoelectric plate extends in the axial direction (the laminating direction) when the internal electrodes are energized, and operates as an actuator.
【０００４】[0004]
【発明が解決しようとする課題】しかし、上記従来の積
層型圧電アクチェータにおいて、電圧の印加を繰り返し
た場合に、圧電板に内部応力が繰り返し発生するため
に、圧電板に亀裂が発生して圧電板が破損するおそれが
ある。つまり圧電板は、電圧の印加により、軸方向に伸
びるとともに、半径方向に縮む。このとき、各圧電板間
に介在する内部電極は電圧が印加されても変形しないた
め、半径方向に縮もうとする圧電板を内部電極が拘束
し、圧電板の変形が抑えられる。このため、圧電板には
剪断による内部応力が発生し、この結果圧電板に亀裂が
発生することとなる。However, in the above-described conventional laminated piezoelectric actuator, when the application of a voltage is repeated, internal stress is repeatedly generated in the piezoelectric plate. The board may be damaged. That is, the piezoelectric plate expands in the axial direction and contracts in the radial direction by applying a voltage. At this time, since the internal electrodes interposed between the piezoelectric plates are not deformed even when a voltage is applied, the internal electrodes restrain the piezoelectric plates that are about to shrink in the radial direction, and the deformation of the piezoelectric plates is suppressed. For this reason, internal stress due to shearing occurs in the piezoelectric plate, and as a result, cracks occur in the piezoelectric plate.
【０００５】このように圧電板が亀裂、破損すると、ア
クチュエータとしての変位特性が低下したり、短絡を生
じたりする問題が起こる。そこで、実開平２−２７７５
５号公報には、上記内部電極として、半径方向に変位が
可能となるように形状を工夫した電極板を用いて、圧電
板の亀裂等を抑制した積層型圧電アクチュエータが開示
されている。しかし、この電極板は、銅の薄板を、波状
の曲線部をもつ多重の環状帯と、この環状帯を連結する
直線状短片とを有する形状に打ち抜き成形したものであ
る。このため、内部電極が局部的に存在するので、駆動
時において、該内部電極により圧電板に積層方向の圧力
が局部的にかかり、これに起因して圧電板が割れたり、
圧電板に作用する電界が不均一となって高精度な電圧−
変位特性を得られないといった欠点がある。[0005] When the piezoelectric plate is cracked or broken in this way, there arise problems that the displacement characteristics of the actuator are degraded or a short circuit is caused. Therefore, 2-2775
Japanese Patent Application Laid-Open No. 5 (1999) -2005 discloses a laminated piezoelectric actuator in which cracks and the like of a piezoelectric plate are suppressed by using an electrode plate whose shape is designed to be displaceable in a radial direction as the internal electrode. However, this electrode plate is formed by stamping a thin copper plate into a shape having multiple annular bands having wavy curved portions and straight short pieces connecting the annular bands. For this reason, since the internal electrodes are locally present, during driving, the pressure in the laminating direction is locally applied to the piezoelectric plate by the internal electrodes, and as a result, the piezoelectric plate is broken,
The electric field acting on the piezoelectric plate becomes non-uniform and a high-precision voltage
There is a disadvantage that displacement characteristics cannot be obtained.
【０００６】本発明は上記実情に鑑みてなされたもので
あり、内部電極を局部的に存在させることなく半径方向
に変位可能として、圧電板の亀裂、割れ等を効果的に抑
制することを目的とするものである。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an object to effectively suppress cracks and cracks of a piezoelectric plate by allowing internal electrodes to be displaced in a radial direction without being locally present. It is assumed that.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決する本第
１発明は、圧電板と内部電極とが交互に多重に積層され
た圧電積層体において、前記内部電極が、放射状に配向
され、かつ、周方向に均一に分布されて、該配向方向に
伸縮可能とされた導電性繊維からなることを特徴とする
ものである。According to a first aspect of the present invention, there is provided a piezoelectric laminate in which piezoelectric plates and internal electrodes are alternately multiplexed and stacked, wherein the internal electrodes are radially oriented, and The conductive fibers are made of conductive fibers that are uniformly distributed in the circumferential direction and can be expanded and contracted in the orientation direction.
【０００８】また上記課題を解決する本第２発明は、圧
電板と内部電極とが交互に多重に積層された圧電積層体
において、前記内部電極が、放射状に配向され、かつ、
周方向に均一に分布されて、該配向方向に伸縮可能とさ
れた繊維と、該繊維の表面上に接合された導電性粒子と
からなることを特徴とするものである。According to a second aspect of the present invention, there is provided a piezoelectric laminated body in which piezoelectric plates and internal electrodes are alternately and multiply laminated, wherein the internal electrodes are radially oriented, and
It is characterized by comprising fibers distributed uniformly in the circumferential direction and capable of expanding and contracting in the orientation direction, and conductive particles bonded on the surface of the fibers.
【０００９】[0009]
【作用】本第１発明では、内部電極が、放射状に配向さ
れて該配向方向に伸縮可能とされた導電性繊維により形
成されているので、駆動時に圧電板が軸方向に伸縮して
放射方向（半径方向）に伸縮したときに、内部電極、つ
まり導電性繊維自身もこれにほぼ追従して伸縮する。こ
のため、内部電極によって、放射方向（半径方向）に伸
縮する圧電板が拘束されて圧電板の変形が抑えられるこ
とがない。したがって、圧電板に剪断による内部応力が
発生することも抑えられ、この結果圧電板に亀裂、割れ
が発生することも抑えられる。なお、本第１発明では、
導電性繊維を介して、圧電板に電圧が印加される。According to the first aspect of the present invention, since the internal electrodes are formed of conductive fibers that are radially oriented and extend and contract in the orientation direction, the piezoelectric plate expands and contracts in the axial direction during driving, so that the radial direction is increased. When it expands and contracts in the (radial direction), the internal electrode, that is, the conductive fiber itself also expands and contracts substantially following this. For this reason, the piezoelectric plate that expands and contracts in the radial direction (radial direction) is not restrained by the internal electrode, and the deformation of the piezoelectric plate is not suppressed. Therefore, generation of internal stress due to shearing in the piezoelectric plate is also suppressed, and as a result, cracks and cracks in the piezoelectric plate are also suppressed. In the first invention,
A voltage is applied to the piezoelectric plate via the conductive fibers.
【００１０】本第２発明においても、駆動時に圧電板が
軸方向に伸縮して放射方向（半径方向）に伸縮したとき
に、放射状に配向されて該配向方向に伸縮可能とされた
繊維がこれにほぼ追従して伸縮する。このため、上記と
同様に、圧電板に亀裂や割れが発生することが抑えられ
る。なお、本第２発明では、繊維の表面に接合された導
電性粒子を介して、圧電板に電圧が印加される。According to the second aspect of the present invention, when the piezoelectric plate expands and contracts in the axial direction and expands and contracts in the radial direction (radial direction) during driving, the fibers which are radially oriented and can expand and contract in the alignment direction are formed. It almost follows and expands and contracts. For this reason, similarly to the above, generation of cracks and cracks in the piezoelectric plate is suppressed. In the second invention, a voltage is applied to the piezoelectric plate via the conductive particles bonded to the surface of the fiber.
【００１１】また、本第１発明及び第２発明において
は、内部電極を構成する繊維が周方向に均一に分布され
ているので、内部電極が局部的に存在することに起因し
て圧電板が割れたり、圧電板に作用する電界が不均一と
なることがない。In the first and second aspects of the present invention, since the fibers constituting the internal electrodes are uniformly distributed in the circumferential direction, the piezoelectric plate is formed due to the local existence of the internal electrodes. There is no cracking or non-uniform electric field acting on the piezoelectric plate.
【００１２】[0012]
【実施例】以下、本発明の圧電積層体を積層型圧電アク
チュエータに適用した実施例を具体的に説明する。 （実施例１）本実施例の積層型圧電アクチェータは、図
３の断面図に示すように、圧電板１と内部電極２とが交
互に多重に積層され、その積層体の外周側面が樹脂絶縁
層３で被覆されている。そして各内部電極２の接合部２
ａは、図示しないリード線にそれぞれ接続された外部電
極４、４に一枚置きに接合されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the piezoelectric laminate of the present invention is applied to a laminated piezoelectric actuator will be specifically described below. (Embodiment 1) As shown in the sectional view of FIG. 3, the laminated piezoelectric actuator of this embodiment has piezoelectric plates 1 and internal electrodes 2 alternately multiplexed and the outer peripheral side surface of the laminated body is resin-insulated. Coated with layer 3. And a joint 2 of each internal electrode 2
a is joined to every other one of the external electrodes 4 connected to lead wires (not shown).
【００１３】上記圧電板１は、ＰＺＴ（ＰｂＺｒＯ3 ・
ＰｂＴｉＯ3 ）系セラミックス製のもので、直径１５ｍ
ｍ、厚さ０．５ｍｍの円板形状を有している。上記内部
電極２は、図１に示すように、直径１５ｍｍ、厚さ０．
０５〜０．１ｍｍの円形状で、周方向の一部分に遠心方
向に３〜５ｍｍ突出した接合部２ａを有している。そし
て、この内部電極２は、図１及び図２に示すように、圧
電板１の中心から外周に向かって連続してほぼ均一に放
射状に配向され、かつ、周方向に均一に分布された繊維
２１と、この繊維２１の表面に主に焼き付けられて接合
された導電性粒子２２と、主に繊維２１と導電性粒子２
２との接着強度を高めるガラス（図示せず）とから構成
されている。また、内部電極２の接合部２ａも、繊維２
１と、この繊維２１の表面に接合された導電性粒子２２
と、主に繊維２１と導電性粒子２２との接着強度を高め
るガラス（図示せず）とから構成されている。なお、導
電性粒子２２の中には、繊維２１の表面に接合されず
に、繊維２１間に存在して導電性粒子２２同士で点接合
されているもの、圧電板１の表面に点接合されているも
のもある。いずれにせよ、内部電極２の構造としては、
最密構造をとっておらず、導電性粒子２２間の間隙の存
在により、繊維２１の放射方向（半径方向）の伸縮は可
能とされている。The piezoelectric plate 1 is made of PZT (PbZrO 3.
It is made of PbTiO 3 ) ceramics and has a diameter of 15 m.
m and a disk shape with a thickness of 0.5 mm. As shown in FIG. 1, the internal electrode 2 has a diameter of 15 mm and a thickness of 0.1 mm.
It has a circular shape of 0.5 to 0.1 mm, and has a joining portion 2a projecting 3 to 5 mm in the centrifugal direction at a part in the circumferential direction. As shown in FIGS. 1 and 2, the internal electrodes 2 are fibers which are continuously and substantially radially oriented from the center of the piezoelectric plate 1 toward the outer periphery and are uniformly distributed in the circumferential direction. 21, conductive particles 22 mainly baked and bonded to the surface of the fibers 21, and mainly the fibers 21 and the conductive particles 2.
And glass (not shown) for increasing the adhesive strength with the glass. Also, the joint 2a of the internal electrode 2 is
1 and conductive particles 22 bonded to the surface of the fiber 21
And glass (not shown) that mainly increases the bonding strength between the fibers 21 and the conductive particles 22. Some of the conductive particles 22 are not bonded to the surface of the fiber 21 but are present between the fibers 21 and are point-joined to each other by the conductive particles 22. Some are. In any case, the structure of the internal electrode 2 is as follows.
The fibers 21 do not have a close-packed structure, and the fibers 21 can expand and contract in the radial direction (radial direction) due to the existence of the gaps between the conductive particles 22.
【００１４】本実施例の積層型圧電アクチュエータは、
以下のようにして製造した。原料粉末としてのＰｂＯ、
ＺｒＯ2 、ＴｉＯ2 をＰｂ（Ｔｉ0.52Ｚｒ0.48）Ｏ 3 の
組成となるように秤量後、ボールミルで湿式混合した
後、乾燥し、８００℃で１時間仮焼きした。そして、再
びボールミルで湿式粉砕した後、乾燥した。この粉末に
バインダとしてのＰＶＡ（ポリビニルアルコール）を約
５重量％加えて造粒後、９８ＭＰａの圧力で、直径１８
ｍｍ、厚さ１ｍｍの円板状の成形体を形成した。The laminated piezoelectric actuator of this embodiment is
It was manufactured as follows. PbO as raw material powder,
ZrOTwo, TiOTwoTo Pb (Ti0.52Zr0.48) O Threeof
After weighing so as to become the composition, it was wet mixed with a ball mill
Thereafter, it was dried and calcined at 800 ° C. for 1 hour. And re
And wet-pulverized with a ball mill and then dried. To this powder
About PVA (polyvinyl alcohol) as binder
After adding 5% by weight and granulating, at a pressure of 98 MPa, a diameter of 18 was obtained.
A disk-shaped molded body having a thickness of 1 mm and a thickness of 1 mm was formed.
【００１５】得られた成形体を、ＺｒＯ2 粉末を充填し
たＡｌ2 Ｏ3 のさやに入れ、昇温速度３００℃／ｈｒで
昇温し、大気炉内１２５０℃で２時間焼成した。一方、
径約０．０５ｍｍの炭素繊維（導電性繊維）をほぼ均一
に放射状に配向させつつ、上記接合部２ａを有する所定
の円板形状に３次元織りした。この繊維の織物を、導電
性粒子としてのＡｇ粒子（粒径：０．１μｍ）：３０重
量部、ガラスフリット：５重量部、及びエタノール：６
５重量部の導電性ペースト中に約３０〜６０分間浸漬し
た。The obtained compact was placed in a sheath of Al 2 O 3 filled with ZrO 2 powder, heated at a heating rate of 300 ° C./hr, and fired at 1250 ° C. for 2 hours in an atmospheric furnace. on the other hand,
A carbon fiber (conductive fiber) having a diameter of about 0.05 mm was three-dimensionally woven into a predetermined disc shape having the above-mentioned joint 2a while radially orientating the carbon fiber almost uniformly. A woven fabric of this fiber was prepared by using 30 parts by weight of Ag particles (particle diameter: 0.1 μm) as conductive particles, 5 parts by weight of glass frit, and 6 parts of ethanol.
It was immersed in 5 parts by weight of the conductive paste for about 30 to 60 minutes.
【００１６】そして、導電性ペーストが含浸された炭素
繊維の織物と、上記圧電セラミックスの焼成体とを交互
に積層し、５００℃の温度で約３０分保持して焼き付け
て、圧電板１と内部電極２とが交互に積層された積層体
を形成した。なお、圧電板１の積層枚数は６０枚であ
る。さらに、この積層体をエポキシ系樹脂中に浸漬し
て、積層体の外周側面に樹脂絶縁層３を形成した。そし
て、樹脂絶縁層３から突出する内部電極２の接合部２ａ
を、金属薄板よりなる外部電極４に溶接により接合し
た。Then, the carbon fiber fabric impregnated with the conductive paste and the fired body of the piezoelectric ceramic are alternately laminated, and are baked at a temperature of 500 ° C. for about 30 minutes to be baked. A laminate in which the electrodes 2 were alternately laminated was formed. The number of stacked piezoelectric plates 1 is 60. Further, this laminate was immersed in an epoxy resin to form a resin insulating layer 3 on the outer peripheral side surface of the laminate. Then, the joint 2a of the internal electrode 2 protruding from the resin insulating layer 3
Was joined to the external electrode 4 made of a thin metal plate by welding.
【００１７】最後に、１００℃の温度で１．５ＫＶ程度
の電圧を印加して分極処理を施して、本実施例の積層型
圧電アクチュエータを完成した。本実施例の積層型圧電
アクチュエータは、内部電極２が半径方向に伸縮可能な
ので、駆動時に、圧電板１にほぼ追従して半径方向に変
位する。このため、圧電板１に剪断により内部応力が発
生することもなく、これに起因する圧電板１の割れ等の
発生を抑えることができる。また、半径方向に変位しな
い従来の内部電極の場合、圧電板１が半径方向に伸びた
ときに、圧電板１よりも内部電極が小さくなって、圧電
板１に十分な電圧をかけることができない場合がある。
しかし、本実施例に係る内部電極２は圧電板１にほぼ追
従して半径方向に変形するので、圧電板１よりも内部電
極２が小さくなることはなく、常に圧電板１に十分な電
圧をかけることが可能である。Finally, a voltage of about 1.5 KV was applied at a temperature of 100 ° C. to perform a polarization treatment, thereby completing the multilayer piezoelectric actuator of this embodiment. In the laminated piezoelectric actuator of the present embodiment, the internal electrode 2 can be expanded and contracted in the radial direction, so that it is displaced in the radial direction substantially following the piezoelectric plate 1 during driving. Therefore, no internal stress is generated in the piezoelectric plate 1 due to shearing, and it is possible to suppress the occurrence of cracks or the like of the piezoelectric plate 1 due to the internal stress. In the case of a conventional internal electrode that does not displace in the radial direction, when the piezoelectric plate 1 extends in the radial direction, the internal electrode becomes smaller than the piezoelectric plate 1 and a sufficient voltage cannot be applied to the piezoelectric plate 1. There are cases.
However, since the internal electrode 2 according to the present embodiment substantially follows the piezoelectric plate 1 and is deformed in the radial direction, the internal electrode 2 does not become smaller than the piezoelectric plate 1 and a sufficient voltage is always applied to the piezoelectric plate 1. It is possible to call.
【００１８】また本実施例のアクチュエータでは、圧電
板１の伸縮に伴って内部電極２のヤング率が変化するの
で、アクチュエータの変位損失を抑制することができ
る。つまり、圧電板１は軸方向に伸びる時に半径方向に
は縮むわけだが、この圧電板１の変形に伴って内部電極
２も半径方向に縮む。これにより、内部電極２を構成す
る繊維２１も半径方向に縮み、内部電極２のヤング率が
向上する。このため、駆動時、圧電板１が軸方向に伸び
た際、内部電極２が軸方向に弾性変形してアクチュエー
タとしての軸方向変位を吸収することが抑えられ、これ
に起因する変位損失を抑えることができる。Further, in the actuator of the present embodiment, the Young's modulus of the internal electrode 2 changes as the piezoelectric plate 1 expands and contracts, so that the displacement loss of the actuator can be suppressed. That is, when the piezoelectric plate 1 expands in the axial direction, it contracts in the radial direction, but with the deformation of the piezoelectric plate 1, the internal electrode 2 also contracts in the radial direction. Accordingly, the fibers 21 constituting the internal electrode 2 also shrink in the radial direction, and the Young's modulus of the internal electrode 2 is improved. Therefore, when the piezoelectric plate 1 is extended in the axial direction during driving, the internal electrode 2 is suppressed from being elastically deformed in the axial direction to absorb the axial displacement as an actuator, and the displacement loss caused by this is suppressed. be able to.
【００１９】さらに本実施例では、内部電極２を構成す
る繊維２１が周方向に均一に分布され、内部電極２が圧
電板１の全面に均一に形成されているので、圧電板に積
層方向の圧力が局部的にかかることに起因して圧電板が
割れたり、圧電板に作用する電界が不均一となって高精
度な電圧−変位特性を得られないといった欠点がない。Further, in the present embodiment, the fibers 21 constituting the internal electrodes 2 are uniformly distributed in the circumferential direction, and the internal electrodes 2 are uniformly formed on the entire surface of the piezoelectric plate 1. There are no drawbacks such as the piezoelectric plate being cracked due to the local application of pressure, and the electric field acting on the piezoelectric plate being non-uniform, making it impossible to obtain highly accurate voltage-displacement characteristics.
【００２０】さらに本実施例では、内部電極２が１層構
造であるため、圧電板の両面に塗布、焼き付けて形成し
た電極と、ＳＵＳ等の金属の電極板とよりなる従来の３
層構造の内部電極と比べて、電極部の厚さを薄くするこ
とができる。このため、アクチュエータ全体の軸方向長
さを小さくすることができる。また、内部電極２による
アクチュエータのヤング率の低下を抑えることができ
る。Further, in this embodiment, since the internal electrode 2 has a one-layer structure, a conventional three-layer structure comprising an electrode formed by applying and baking on both sides of a piezoelectric plate and an electrode plate of a metal such as SUS is used.
The thickness of the electrode portion can be reduced as compared with the internal electrode having a layer structure. Therefore, the axial length of the entire actuator can be reduced. In addition, a decrease in the Young's modulus of the actuator due to the internal electrode 2 can be suppressed.
【００２１】さらに本実施例では、内部電極２を構成す
るＡｇ粒子が圧電板１の微細な凹凸表面に点接合してい
るため、圧電板１と内部電極２との間で大きな接触面積
が確保されており、内部電極２から圧電板１に効果的に
電圧をかけることが可能である。さらにまた、本実施例
では、内部電極２の接合部２ａも伸縮可能であるため、
外部電極４に対して積層体が軸方向や半径方向に相対変
位したときも、この変位を接合部２ａが吸収する。この
ため、内部電極２の接合部２ａと外部電極４との切断を
効果的に防止することができる。Further, in this embodiment, since the Ag particles constituting the internal electrode 2 are point-joined to the fine uneven surface of the piezoelectric plate 1, a large contact area is secured between the piezoelectric plate 1 and the internal electrode 2. Therefore, it is possible to effectively apply a voltage to the piezoelectric plate 1 from the internal electrodes 2. Furthermore, in this embodiment, since the joint 2a of the internal electrode 2 is also expandable,
Even when the laminate is displaced relative to the external electrode 4 in the axial direction or the radial direction, the joint 2a absorbs this displacement. For this reason, it is possible to effectively prevent disconnection between the joint 2a of the internal electrode 2 and the external electrode 4.
【００２２】（耐久試験）本実施例の積層型圧電アクチ
ュエータ１０個について、電圧：−２００〜６００Ｖ、
プリセット面圧：２８ＭＰａ、雰囲気温度：１３０℃の
条件で繰り返し駆動させる耐久試験を行った。その結果
を良品率として図４に示す。なお、これは、試験後のア
クチュエータにおいて圧電板１が１枚でも亀裂、破損し
ていたら、破壊品として数え、良品率（％）＝｛１−
（破壊品数）／（試験総数）｝×１００の計算式より求
めた。(Durability test) With respect to ten laminated piezoelectric actuators of this embodiment, a voltage: -200 to 600 V,
A durability test was performed in which the device was repeatedly driven under the conditions of a preset surface pressure: 28 MPa and an ambient temperature: 130 ° C. The results are shown in FIG. This means that if even one piezoelectric plate 1 is cracked or broken in the actuator after the test, it is counted as a broken product, and the non-defective product rate (%) = ｛1−
It was determined from the formula of (number of broken products) / (total number of tests) x 100.
【００２３】比較のため、積層体の内部電極を、圧電板
の表裏面に焼き付け形成した銀ペースト電極と、ＳＵＳ
よりなる電極板とにより構成すること以外は本実施例と
同様の比較例の積層型圧電アクチュエータについても、
同様に耐久試験を行った。その結果を図４に併せて示
す。図４からも明らかなように、比較例に係る積層型圧
電アクチュエータは、３×１０8 回の駆動回数後に良品
率が７０％程度まで低下したのに対し、本実施例に係る
ものは、３×１０8 回の駆動回数後においても良品率が
ほぼ１００％を維持していた。したがって、本発明の内
部電極２の構造により、圧電板１の破損等を効果的に抑
制できることが確認された。For comparison, a silver paste electrode formed by baking on the front and back surfaces of a piezoelectric plate and a SUS
A multilayer piezoelectric actuator of a comparative example similar to the present example except that the piezoelectric actuator is constituted by an electrode plate made of
A durability test was performed in the same manner. The results are shown in FIG. As is clear from FIG. 4, the non-defective product ratio of the laminated piezoelectric actuator according to the comparative example was reduced to about 70% after the number of driving times of 3 × 10 8 times, whereas that of the laminated piezoelectric actuator according to this example was 3%. Even after the driving of × 10 8 , the non-defective rate was maintained at almost 100%. Therefore, it was confirmed that the structure of the internal electrode 2 of the present invention can effectively suppress breakage of the piezoelectric plate 1 and the like.
【００２４】なお、上記実施例では、繊維の織物に導電
性ペーストを含浸させる方法として、導電性ペースト中
に繊維の織物を浸漬する方法を採用したが、これの代わ
りに繊維の織物に導電性ペーストを圧力をかけながら注
入する方法も採用することが可能である。また、上記実
施例では、予め焼成した圧電板１を形成しておき、この
圧電板１とＡｇ粒子を含浸した繊維の織物とを積層した
後に、焼き付けて積層体とする方法を採用したが、これ
の代わりに、所定形状に成形した圧電セラミックスのグ
リーンシートと、導電性粒子を含浸した繊維の織物とを
積層し、圧電セラミックスの焼成温度に焼成して積層体
とすることも可能である。ただしこの場合は、導電性粒
子及び繊維として上記焼成温度に耐え得るものを選択す
る必要がある。In the above embodiment, as a method of impregnating the conductive fabric with the conductive paste, the method of immersing the conductive fabric in the conductive paste is used. It is also possible to adopt a method of injecting the paste while applying pressure. Further, in the above-described embodiment, a method is adopted in which the piezoelectric plate 1 is formed in advance, the piezoelectric plate 1 is laminated with a fiber woven fabric impregnated with Ag particles, and then baked to form a laminate. Instead of this, it is also possible to laminate a green sheet of a piezoelectric ceramic formed into a predetermined shape and a woven fabric of fibers impregnated with conductive particles, and fire the same at the firing temperature of the piezoelectric ceramic to form a laminate. However, in this case, it is necessary to select conductive particles and fibers that can withstand the above firing temperature.
【００２５】さらに上記実施例では、導電性粒子とし
て、Ａｇ粒子を用いたが、これの代わりにＡｕ，Ｎｉ，
Ａｌ，Ｐｔ，Ｐｄ等の他の導電性粒子を用いることも可
能である。 （実施例２）上記実施例１では、内部電極２の形成方法
として、３次元織りにより繊維の織物を予め形成し、こ
れに導電性ペーストを含浸させる方法を採用したが、本
実施例２はこれの代わりに以下の方法により内部電極２
を形成した。また、上記実施例１では、繊維２１として
導電性繊維である炭素繊維を用いたが、本実施例２では
これの代わりに非導電性繊維としてのガラス繊維を用い
た。Furthermore, in the above embodiment, Ag particles were used as the conductive particles, but instead of Au, Ni,
Other conductive particles such as Al, Pt, and Pd can be used. (Embodiment 2) In Embodiment 1, as a method for forming the internal electrode 2, a method of forming a fiber woven fabric in advance by three-dimensional weaving and impregnating the fabric with a conductive paste was employed. Instead of this, the internal electrode 2 is formed by the following method.
Was formed. In the first embodiment, the carbon fibers which are the conductive fibers are used as the fibers 21, but in the second embodiment, the glass fibers are used as the non-conductive fibers instead.
【００２６】まず、導電性粒子としてのＡｇ粒子（粒
径：０．１μｍ）：３０重量部、ガラスフリット：５重
量部、及びエタノール：６５重量部よりなる導電性ペー
ストを準備した。この導電性ペースト中に、長さ１ｍ
ｍ、径０．０１〜０．５ｍｍのガラス繊維（導電性ペー
スト１００重量部に対して５０重量部）を入れ、ボール
ミルで４８時間、十分に攪拌、分散して分散液とした。First, a conductive paste composed of 30 parts by weight of Ag particles (particle size: 0.1 μm), 5 parts by weight of glass frit, and 65 parts by weight of ethanol as conductive particles was prepared. 1m long in this conductive paste
m, glass fiber having a diameter of 0.01 to 0.5 mm (50 parts by weight with respect to 100 parts by weight of the conductive paste) was put therein, and sufficiently stirred and dispersed by a ball mill for 48 hours to obtain a dispersion.
【００２７】また、中心孔を有し、この中心孔に注入用
管（径３ｍｍ）が突設されたディスク（直径５０ｍｍ）
を準備した。このディスクを上記実施例１と同様にして
得た圧電セラミックスの焼成体の上に、０．０５〜０．
１ｍｍ程度離して保持した状態で、注入用管から上記分
散液を圧力をかけながら１０分程度注入した。これによ
り、分散液が焼成体の中心から放射状に流れて、外周か
ら流れ出るので、分散液中の各繊維が放射状に配向し
た。そして、上記ガラス繊維を長手方向に配向させつつ
所定形状（５ｍｍ×２ｍｍ）に３次元織りした接合部２
ａを、繊維の配向方向が同じとなるように所定位置に配
設した。A disk (50 mm in diameter) having a center hole, into which an injection tube (3 mm in diameter) protrudes.
Was prepared. This disk was placed on a fired body of piezoelectric ceramic obtained in the same manner as in Example 1 above, and was placed in the range of 0.05 to 0.1.
The dispersion was injected from the injection tube for about 10 minutes while applying pressure while being held at a distance of about 1 mm. As a result, the dispersion liquid radially flows from the center of the fired body and flows out from the outer periphery, so that each fiber in the dispersion liquid is radially oriented. Then, the joining portion 2 is formed by three-dimensionally weaving the glass fiber into a predetermined shape (5 mm × 2 mm) while orienting the glass fiber in the longitudinal direction.
a was disposed at a predetermined position so that the orientation directions of the fibers were the same.
【００２８】この後、このように形成した分散液付の焼
成体を６０枚積層し、５００℃の温度で約３０分保持し
て焼き付けて、圧電板１と内部電極２とが交互に積層さ
れた積層体を形成した。そして、上記実施例１と同様に
積層型圧電アクチュエータとした。なお、上記実施例２
では、非導電性繊維としてガラス繊維を用いたが、これ
の代わりにアラミド繊維やポリエチレン繊維等の他の非
導電性繊維を用いることも可能である。Thereafter, 60 pieces of the fired bodies with the dispersion liquid formed as described above are laminated, baked at a temperature of 500 ° C. for about 30 minutes, and the piezoelectric plates 1 and the internal electrodes 2 are alternately laminated. A laminated body was formed. Then, similarly to the first embodiment, a laminated piezoelectric actuator was obtained. In addition, the second embodiment
In the above, glass fiber was used as the non-conductive fiber, but another non-conductive fiber such as aramid fiber or polyethylene fiber may be used instead.
【００２９】（実施例３）本実施例３の積層型圧電アク
チュエータは、内部電極２を導電性繊維のみから構成し
たものである。つまり、本実施例３に係る内部電極２
は、圧電板１の中心から外周に向かって連続してほぼ均
一に放射状に配向された繊維２１のみから構成されてい
る。(Embodiment 3) In the laminated piezoelectric actuator of Embodiment 3, the internal electrodes 2 are formed only of conductive fibers. That is, the internal electrode 2 according to the third embodiment
Is composed of only the fibers 21 which are radially oriented substantially uniformly continuously from the center of the piezoelectric plate 1 toward the outer periphery.
【００３０】本実施例の積層型圧電アクチュエータは、
上記実施例１で準備した炭素繊維の織物と、同じく上記
実施例１で準備した圧電セラミックスの焼成体とを交互
に積層し、不活性雰囲気中５００℃の温度で約３０分保
持して焼き付けて、圧電板１と内部電極２とが交互に積
層された積層体を形成した。そして、上記実施例１と同
様に積層型圧電アクチュエータとした。The laminated piezoelectric actuator of this embodiment is
The carbon fiber fabric prepared in Example 1 and the piezoelectric ceramic fired body similarly prepared in Example 1 are alternately laminated, and baked in an inert atmosphere at a temperature of 500 ° C. for about 30 minutes. Then, a laminate in which the piezoelectric plates 1 and the internal electrodes 2 were alternately laminated was formed. Then, similarly to the first embodiment, a laminated piezoelectric actuator was obtained.
【００３１】上記実施例２及び実施例３の積層型圧電ア
クチュエータについても、上記実施例１と同様の耐久試
験を行った結果、ほぼ同様の結果が得られた。With respect to the laminated piezoelectric actuators of Examples 2 and 3, a durability test similar to that of Example 1 was performed. As a result, almost the same results were obtained.
【００３２】[0032]
【発明の効果】以上詳述したように本発明の圧電積層体
は、内部電極が放射方向に伸縮可能であるため、圧電板
の放射方向の変位に追従して内部電極が変位する。この
ため、圧電板の放射方向の変位が内部電極で拘束され
て、圧電板に剪断による内部応力が発生することがな
い。したがって、圧電板に亀裂や割れが発生することを
効果的に防止することができる。As described in detail above, in the piezoelectric laminate of the present invention, since the internal electrodes can expand and contract in the radial direction, the internal electrodes are displaced following the radial displacement of the piezoelectric plate. For this reason, the radial displacement of the piezoelectric plate is not restricted by the internal electrodes, and no internal stress is generated in the piezoelectric plate due to shearing. Therefore, it is possible to effectively prevent the piezoelectric plate from cracking or cracking.
【００３３】また、本発明の圧電積層体は、内部電極を
構成する繊維が周方向に均一に分布されているので、局
部的に内部電極から圧電板に積層方向の圧力がかかって
圧電板が割れたり、圧電板に作用する電界が不均一とな
って高精度な電圧−変位特性を得られないといった不都
合がない。さらに、本発明の圧電積層体は、駆動時に内
部電極が圧電板の伸縮に伴って内部電極のヤング率が変
化するので、アクチュエータの変位損失を抑制すること
ができる。Further, in the piezoelectric laminate of the present invention, since the fibers constituting the internal electrodes are uniformly distributed in the circumferential direction, the pressure in the laminating direction is locally applied to the piezoelectric plate from the internal electrodes, so that the piezoelectric plate is pressed. There is no inconvenience that the electric field acting on the piezoelectric plate is broken and the voltage-displacement characteristics with high accuracy cannot be obtained. Further, in the piezoelectric laminate of the present invention, the internal electrode changes in Young's modulus of the internal electrode as the piezoelectric plate expands and contracts during driving, so that the displacement loss of the actuator can be suppressed.
【図１】本実施例に係る内部電極を模式的に示す平面図
である。FIG. 1 is a plan view schematically showing an internal electrode according to the present embodiment.
【図２】本実施例に係る内部電極を模式的に示す拡大断
面図である。FIG. 2 is an enlarged sectional view schematically showing an internal electrode according to the present embodiment.
【図３】本実施例に係る圧電積層体を模式的に示す断面
図である。FIG. 3 is a cross-sectional view schematically illustrating a piezoelectric laminate according to the present embodiment.
【図４】本実施例及び比較例の圧電積層体について、耐
久試験を行った結果を示す線図である。FIG. 4 is a diagram showing the results of a durability test performed on the piezoelectric laminates of this example and a comparative example.
１は圧電板、２は内部電極、２１は繊維、２２は導電性
粒子である。1 is a piezoelectric plate, 2 is an internal electrode, 21 is a fiber, and 22 is a conductive particle.
Claims (2)
された圧電積層体において、 前記内部電極は、放射状に配向され、かつ、周方向に均
一に分布されて、該配向方向に伸縮可能とされた導電性
繊維からなることを特徴とする圧電積層体。1. A piezoelectric laminate in which a plurality of piezoelectric plates and internal electrodes are alternately stacked, wherein the internal electrodes are radially oriented and uniformly distributed in a circumferential direction, and expand and contract in the alignment direction. A piezoelectric laminate comprising conductive fibers made possible.
された圧電積層体において、 前記内部電極は、放射状に配向され、かつ、周方向に均
一に分布されて、該配向方向に伸縮可能とされた繊維
と、該繊維の表面上に接合された導電性粒子とからなる
ことを特徴とする圧電積層体。2. In a piezoelectric laminate in which piezoelectric plates and internal electrodes are alternately stacked in multiple layers, the internal electrodes are radially oriented and uniformly distributed in a circumferential direction, and expand and contract in the orientation direction. A piezoelectric laminate comprising a fiber made possible and conductive particles bonded on the surface of the fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4335862A JP3070311B2 (en) | 1992-12-16 | 1992-12-16 | Piezoelectric laminate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4335862A JP3070311B2 (en) | 1992-12-16 | 1992-12-16 | Piezoelectric laminate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06188473A JPH06188473A (en) | 1994-07-08 |
| JP3070311B2 true JP3070311B2 (en) | 2000-07-31 |
Family
ID=18293216
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4335862A Expired - Fee Related JP3070311B2 (en) | 1992-12-16 | 1992-12-16 | Piezoelectric laminate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3070311B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1179860A1 (en) * | 2000-08-09 | 2002-02-13 | Piezomechanik GmbH | Contact for piezoelectric actuators |
| FR2959877B1 (en) * | 2010-05-06 | 2013-06-14 | Renault Sa | METHOD OF MANUFACTURING A STACK ACTUATOR WITH ALTERNATE ELECTRODE LAYER LAYERS AND PIEZOELECTRIC MATERIAL |
| JP7293898B2 (en) * | 2019-06-18 | 2023-06-20 | Tdk株式会社 | Piezoelectric element |
-
1992
- 1992-12-16 JP JP4335862A patent/JP3070311B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06188473A (en) | 1994-07-08 |
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