JPH02131375A - Torus-shaped ultrasonic motor - Google Patents

Abstract

PURPOSE:To improve output efficiency by providing a protruding part between specific wavelength of an elastic unit constituting a vibrator, and exciting an elastic vibration of (n) wave in one direction of rotation while of predetermined integral wave other than the (n) wave in the other direction of rotation. CONSTITUTION:A vibrator 9 is constituted of a piezoelectric unit 8 and an elastic unit 7, and a protruding part 10 is provided in any part at least between 0 to 1/4 or 1/2 to 3/4 wavelength or 1/4 to 1/2 or 3/4 to 1 wavelength for the elastic unit 7. In one direction of rotation 11, an elastic vibration of (n) wave is excited, and in the other direction of rotation 12, an elastic vibration of integral wave except the (n) wave further with a vibration locus of the protruding part 10 in the direction 11 changed into an opposite direction is excited. In this way, normal and reverse rotation can be obtained by only a single elastic vibration further enabling the vibration to be fixedly supported in a node in the same position.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は圧電体の弾性振動を用いて駆動力を発生する円
環形超音波モータの構成に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of an annular ultrasonic motor that generates driving force using elastic vibrations of a piezoelectric body.

従来の技術 近年、圧電セラミック等の圧電体を用いた振動体に弾性
振動を励振し、これを駆動力とした超音波モータが注目
されている。2. Description of the Related Art In recent years, ultrasonic motors have attracted attention in which elastic vibrations are excited in a vibrating body using a piezoelectric material such as a piezoelectric ceramic, and the vibrations are used as a driving force.

以下、図面を参照しながら超音波モータの従来技術につ
いて詳細に説明する。Hereinafter, the conventional technology of an ultrasonic motor will be explained in detail with reference to the drawings.

第３図は径方向１次、周方向３次以上の円環形超音波モ
ータの切り欠き斜視図であり、円環形の弾性体１に円環
形圧電体２を貼合せて振動体３を構成している。第４図
は円環形超音波モータの径方向１次の振動モードを用い
た時の振動姿態と振動変位を示す図である。４は耐磨耗
性材料の摩擦材、５は弾性体であり、互いに貼合せられ
て移動体６を構成している。移動体６は摩擦材４を介し
て振動体３と接触している。圧電体２に電界を印加する
と振動体３の周方向に曲げ擾動の進行波が励起され、移
動体６を駆動する。尚、同図中の矢印は移動体６の回転
方向を示す。FIG. 3 is a cutaway perspective view of an annular ultrasonic motor with primary order in the radial direction and tertiary or higher order in the circumferential direction. ing. FIG. 4 is a diagram showing the vibration mode and vibration displacement when the first-order vibration mode in the radial direction of the annular ultrasonic motor is used. Reference numeral 4 indicates a friction material made of a wear-resistant material, and reference numeral 5 indicates an elastic body, which are pasted together to form a moving body 6. The moving body 6 is in contact with the vibrating body 3 via the friction material 4. When an electric field is applied to the piezoelectric body 2, a traveling wave of bending vibration is excited in the circumferential direction of the vibrating body 3, thereby driving the movable body 6. Note that the arrow in the figure indicates the rotation direction of the moving body 6.

第５図は第３図の超音波モータに使用した圧電体２の電
極構造の一例を示している。同図では円？方向に９波の
弾性波がのるようにしてある。ＡおよびＢはそれぞれ２
分の１波長相当の小領域から成る電極群で、Ｃは４分の
３波長相当、Ｄは４分の１波長相当の電極である。電極
ＣおよびＤは電極群ＡとＢに位置的に４分の１波長（＝
９０度）の位相差を作るために設けている。電極ＡとＢ
内の隣り合う小電極部は互いに反対に厚み方向に分極さ
れている。圧電体２の弾性体１との接着面は、第５図に
示された面と反対の面であり、電極はべ夕電極である。FIG. 5 shows an example of the electrode structure of the piezoelectric body 2 used in the ultrasonic motor of FIG. Is it a circle in the same figure? Nine elastic waves are placed in the direction. A and B are each 2
This is an electrode group consisting of a small region corresponding to one-quarter wavelength, where C is an electrode corresponding to three-quarter wavelength and D is an electrode corresponding to one-quarter wavelength. Electrodes C and D are positioned at a quarter wavelength (=
This is provided to create a phase difference of 90 degrees. Electrodes A and B
Adjacent small electrode portions within the electrode are polarized in opposite directions in the thickness direction. The bonding surface of the piezoelectric body 2 to the elastic body 1 is the surface opposite to the surface shown in FIG. 5, and the electrode is a solid electrode.

使用時には、電極群ＡおよびＢは同図に斜線で示したよ
うに、それぞれ短絡して用いられる。During use, electrode groups A and B are short-circuited, as indicated by diagonal lines in the figure.

以上のように構成された超音波モータの圧電体２の電極
ＡおよびＢに Ｖ　ｉ−ＶｏＸｓｉｎ（ωｔ）　　　　　　　　−−−
（１）Ｖ　２　−Ｖ　Ｏ　ｘｃ■ｓ（ωｔ）　　　　　
　　　−−−（２）ただし、ｖＯ：電圧の瞬時値 ω：角周波数 ｔ：時間 で表される電圧ｖ１およびｖ２をそれぞれ印加すれば、
振動体３には ξ−ξｏ　ｘ（ｃｏｓ（　ωｔ　）ｘｃｏｓ（ｋｘ　）
＋ｓｉｎ（　ωｔ）ｘｓｉｎ（ｋｘ））一ξｏｘｃｏｓ
（ｃｃ＞ｔ−ｋｘ）　　　　　　−−−（３）ただし　
ξ：曲げ振動の娠幅値 ξ０：曲げ振動の瞬時値 ｋ　：波数（２π／λ） λ：波長 Ｘ　：位置 で表せる、円周方向に進行する曲げ振動の進行波が励振
される。Vi−VoXsin(ωt) at the electrodes A and B of the piezoelectric body 2 of the ultrasonic motor configured as above
(1) V 2 −V O xc■s(ωt)
---(2) However, vO: Instantaneous value of voltage ω: Angular frequency t: If voltages v1 and v2 expressed in time are applied, respectively,
The vibration body 3 has ξ−ξox(cos(ωt)xcos(kx)
+sin(ωt)xsin(kx))−ξoxcos
(cc>t-kx) ---(3) However
ξ: Stretch width value of bending vibration ξ0: Instantaneous value of bending vibration k: Wave number (2π/λ) λ: Wavelength

第６図は振動体３の表面のＡ点が進行波の励起によって
、長軸２ｗ、短軸２ｕの楕円運動をし、振動体３上に加
圧して設置された移動体６が、楕円の頂点近傍で接触す
ることにより、摩擦力により波の進行方向とは逆方向に
Ｖ−ω×ｕの速度で運動する様子を示している。FIG. 6 shows that point A on the surface of the vibrating body 3 moves in an ellipse with the long axis 2w and the short axis 2u due to the excitation of the traveling wave, and the movable body 6 placed under pressure on the vibrating body 3 moves in an ellipse. This figure shows how the waves move at a speed of V-ω×u in the direction opposite to the direction of wave travel due to frictional force due to contact near the apex.

機械出力を大きくするには、振動体の進行方向の変位成
分Ｕを太き《すればよい。そのために、第７図に示すよ
うに振動体に柱状の突起体７を設ける。柱状の突起体７
により、曲げ振動による進行方向の成分Ｕは拡大される
ので、機械出力を増大できる。In order to increase the mechanical output, the displacement component U in the traveling direction of the vibrating body should be made thicker. For this purpose, columnar protrusions 7 are provided on the vibrating body as shown in FIG. Columnar projection 7
As a result, the component U in the traveling direction due to bending vibration is expanded, so that the mechanical output can be increased.

発明が解決しようとする課題 従来の円環形超音波モータは、弾性進行波を用いている
ため径方向に対しても周方向においても節円や節線とな
る節が存在せず、振動を阻害しないように固定や支持を
行う事ができないという重大な問題がある。改善のため
に弾性的に柔らかい物質（例えばフェルト材）で支持し
ても移動体の加圧時に生じる物質の変形によって振動体
と移動体の接触状態を一定に保でな《なり機械出力の取
り出しにおいて動力伝達の効率が悪《出力効率が低下す
るという問題がある。また、時間的・位相的に興なる２
つの波の合成で弾性進行波を励振するため、加工や電極
位置精度による駆動周波数ズレなどで容易に２つの波の
振幅差で生じる定在波が発生し、それにより安定した特
性が得られず、駆動回路による制御が困難であった。Problems to be Solved by the Invention Conventional annular ultrasonic motors use elastic traveling waves, so there are no nodal circles or nodal lines in the radial or circumferential direction, which inhibits vibration. There is a serious problem in that it cannot be fixed or supported to prevent it from happening. Even if the movable body is supported with an elastically soft material (for example, felt material) for improvement, the contact state between the vibrating body and the movable body cannot be maintained constant due to the deformation of the material that occurs when the movable body is pressurized, resulting in the extraction of mechanical output. There is a problem that the efficiency of power transmission is poor (the output efficiency is reduced). In addition, 2 that arises temporally and topologically
Since an elastic traveling wave is excited by combining two waves, a standing wave caused by the amplitude difference between the two waves can easily occur due to drive frequency deviation due to processing or electrode position accuracy, making it difficult to obtain stable characteristics. , control by the drive circuit was difficult.

本発明はかかる点に鑑みてなされたもので、支持固定が
でき、効率の良い、しかも長寿命で高信頼性の超音波モ
ータを提供することを目的としている。The present invention has been made in view of these points, and an object of the present invention is to provide an ultrasonic motor that can be supported and fixed, is efficient, has a long life, and is highly reliable.

課題を解決するための手段 本発明は振動体に、少なくともＯ〜１／４か１／２〜３
／４波長の間あるいは１／４〜１／２か３／４〜１波長
の間のいずれかに凸部を設け、方の回転方向ではｎ波の
弾性振動を印加し他方の回転方向（Ｂ）では、ｎ波以外
で、しかも一方の回転方向の凸部の振動軌跡が反対方向
となるような整数波の弾性振動で励振する構成としたも
のである。Means for Solving the Problems The present invention provides a vibrating body with at least 0 to 1/4 or 1/2 to 3
A convex portion is provided between /4 wavelength, between 1/4 and 1/2, or between 3/4 and 1 wavelength, and n-wave elastic vibration is applied in one direction of rotation, and vibration is applied in the other direction of rotation (B ), the structure is such that the vibration is excited by an integer wave elastic vibration other than the n wave, and in which the vibration locus of the convex portion in one direction of rotation is in the opposite direction.

作用 振動体に、一方の回転方向ではｎ波の弾性振動に対して
、少なくとも０〜１／４か１／２〜３／４波長の間ある
いは１／４〜１／２か３／４〜１波長の間のいずれかに
凸部を設け、他方の回転方向（Ｂ）では、ｎ波以外で、
しかも一方の回転方向の凸部の振動軌跡が反対方向とな
るような整数波の弾性振動で励振する。これにより両回
転方向の励振はいずれも一つの定在波のみで駆動するた
め、両回転方向を励振する二つの定在波に共通に存在す
る節で支持固定を行うことができ、特性の安定した高信
頼性の超音波モータを実現するものである。The acting vibrator has at least 0 to 1/4 or 1/2 to 3/4 wavelength or 1/4 to 1/2 or 3/4 to 1 wavelength for n-wave elastic vibration in one direction of rotation. A convex portion is provided somewhere between the wavelengths, and in the other rotation direction (B), other than the n wave,
Moreover, it is excited with integral wave elastic vibration such that the vibration locus of the convex portion in one direction of rotation is in the opposite direction. As a result, excitation in both rotational directions is driven by only one standing wave, so it is possible to support and fix at nodes that are common to the two standing waves that excite both rotational directions, resulting in stable characteristics. The aim is to realize a highly reliable ultrasonic motor.

実施例 以下、図面に従って本発明の実施例について詳細な説明
を行う。EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

第１図（ａ）〜（ｆ）は本発明の円環形超音波モータの
動作原理を示す図である。同図（ｂ）において、凸部１
０はＯ〜１７４波長間毎に設けている。この弾性体７と
圧電体８からなる振動体９に同図（ｃ）に示した極性の
電界を圧電体８に印加すれば同図（ａ）のようなｎ波の
弾性振動が励振できる。ｎ波の弾性振動によって同図（
ｂ）に示した様に凸部１０の頂点は運動し、頂点に加圧
接触した移動体１２は矢印の方向１１に移動することに
なる。一方、第１図（ｆ）に示した極性の電界を圧電体
８に印加すれば同図（ｄ）のようなｎ／２波の弾性振動
が励振できる。このｎ／２波の弾性振動により同図（ｅ
）に示した様に凸部１０の頂点は（ｂ）とは反対の振動
軌跡で運動するため移動体１２は矢印の方向１３に移動
する。これにより正逆の回転が容易に得られる。第２図
（ａ）〜（ｃ）は本発明の円環形超音波モータの駆動方
法の一例を示す図である。同図（ａ）において、矢印の
方向に交互に分極処理した圧電体１４に図のＶａ，Ｖｂ
ように電極１６を結線する。FIGS. 1(a) to 1(f) are diagrams showing the operating principle of the annular ultrasonic motor of the present invention. In the same figure (b), the convex portion 1
0 is provided every 0 to 174 wavelengths. By applying an electric field having the polarity shown in FIG. 12(c) to the vibrating body 9 composed of the elastic body 7 and the piezoelectric material 8, n-wave elastic vibrations as shown in FIG. 4(a) can be excited. The same figure (
As shown in b), the apex of the convex portion 10 moves, and the movable body 12 that presses into contact with the apex moves in the direction 11 of the arrow. On the other hand, if an electric field with the polarity shown in FIG. 1(f) is applied to the piezoelectric body 8, an n/2 wave elastic vibration as shown in FIG. 1(d) can be excited. This n/2 wave elastic vibration causes the same figure (e
), the vertex of the convex portion 10 moves in a vibration locus opposite to that shown in (b), so the movable body 12 moves in the direction 13 of the arrow. This allows forward and reverse rotation to be easily obtained. FIGS. 2(a) to 2(c) are diagrams showing an example of the method for driving the annular ultrasonic motor of the present invention. In the same figure (a), the piezoelectric body 14 is polarized alternately in the direction of the arrow.
Connect the electrodes 16 as shown.

ここで、圧電体１４の電極１６に Ｖａ＝Ｖｂ＝ＶｏＸｓ　ｉｎ　（ωｔ）ただし、ｖｏ：
電圧の瞬時値 ω　：角周波数 ｔ　；時間 で表される電圧を印加すれば、振動体９は同図（ｂ）で
示されるｎ波の弾性振動が励振される。Here, for the electrode 16 of the piezoelectric body 14, Va=Vb=VoXs in (ωt) However, vo:
Instantaneous value ω of voltage: angular frequency t; When a voltage expressed in time is applied, the vibrating body 9 is excited with n-wave elastic vibrations as shown in FIG. 4(b).

同様に、 Ｖａ＝　　ＶｏＸｓ　ｉｎ　（ωｔ） Ｖｂ＝−ＶｏＸｓ　ｉｎ　（ωｔ） で表される電圧Ｖ．ａ，Ｖｂを印加すれば、振動体９は
同図（ｃ）で示されるｎ／２波の弾性振動が励振される
。Similarly, the voltage V. expressed as Va=VoXs in (ωt) Vb=-VoXs in (ωt). When a and Vb are applied, the vibrating body 9 is excited with n/2 wave elastic vibrations as shown in FIG. 3(c).

上記のように一つの弾性振動だけで回転方向を制御する
ことができ、しかも電圧の極性だけで実現できるため、
駆動が非常に簡略化できる。また、第１図（ａ）および
（ｄ）に示した弾性振動には、同じ位置に節１５を持つ
のでその節１５で容易にビス等で支持固定ができる。そ
の結果、特性の安定や高効率化がはかれるものである。As mentioned above, the direction of rotation can be controlled with just one elastic vibration, and it can also be achieved using only the polarity of the voltage.
Driving can be greatly simplified. Furthermore, since the elastic vibrations shown in FIGS. 1(a) and 1(d) have nodes 15 at the same position, the nodes 15 can be easily supported and fixed with screws or the like. As a result, stable characteristics and high efficiency can be achieved.

上述は、ｎ波の弾性振動に対してＯ〜１／４波長間に凸
部を設けた構成について述べたが、１／２〜３／４波長
間に同時にあるいは単独に設けても同様の動作ができる
ことは言うまでもな《、この場合、回転方向を逆にする
ためには励振方法を変えるだけでよい。このように同様
の動作ができれば、どこに凸部を設けても良く特に限定
されるものではない。The above description has been about a configuration in which a convex portion is provided between O and 1/4 wavelengths for n-wave elastic vibration, but the same operation can be achieved even if the convex portion is provided between 1/2 and 3/4 wavelengths simultaneously or singly. Needless to say, it is possible to reverse the rotation direction by simply changing the excitation method. As long as similar operations can be performed, the convex portion may be provided anywhere and there is no particular limitation.

発明の効果 本発明では、振動体に、一方の回転方向ではｎ波の弾性
振動に対して、少なくともＯ〜１／４か１／２〜３／４
波長の間あるいは１／４〜１／２か３／４〜１波長の間
のいずれかに凸部を設け、他方の回転方向では、ｎ波以
外で、しかも一方の回転方向の凸部の振動軌跡が反対方
向となるような整数波の弾性振動で励振することにより
、一つの弾性振動のみで正逆回転が得られ、かつ同位置
の節で支持固定できるため、従来方式のような支持によ
る振動損失がほとんど無く高効率化がはかれる。また、
回転方向の制御も電圧の極性の切り替えのみで行えるの
で駆動回路の大幅な簡略化ができ、応用上非常に有意義
な超音波モータを提供できるものである。Effects of the Invention In the present invention, the vibrating body has at least 0 to 1/4 or 1/2 to 3/4 of n-wave elastic vibration in one direction of rotation.
A convex portion is provided between wavelengths or between 1/4 to 1/2 or 3/4 to 1 wavelength, and in the other rotation direction, vibration of the convex portion in one direction of rotation is generated other than the n wave. By exciting with integer wave elastic vibrations whose trajectories are in opposite directions, forward and reverse rotation can be obtained with only one elastic vibration, and the nodes at the same position can be supported and fixed, making it possible to achieve High efficiency can be achieved with almost no vibration loss. Also,
Since the direction of rotation can be controlled simply by switching the polarity of the voltage, the drive circuit can be greatly simplified, and an ultrasonic motor that is extremely useful in terms of applications can be provided.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の円環形超音波モータの動作原理を示す
図、第２図は本発明の円環形超音波モータの駆動方法の
一例を示す図、第３図は従来の円環形超音波モータの切
り欠き斜視図、第４図は円環形超音波モータの径方向１
次の振動モードを用いた時の振動姿態と振動変位を示す
図、第５図は第３図の超音波モータに用いた圧電体の形
状と電極構造を示す平面図、第６図は従来の超音波モー
夕の動作原理の説明図、第７図は振動体に突起体を設け
た円環形超音波モータの切り欠き斜視図。 ７・・・・・・弾性体、８・・・・・・圧電体、９・・
・・・・振動体、１０・・・・・・凸部、１２・・・・
・・移動体。 代理人の氏名　弁理士　粟野重孝　ほか１名第 図 第 第 図 図 Ｂ ハ 第 図Fig. 1 is a diagram showing the operating principle of the annular ultrasonic motor of the present invention, Fig. 2 is a diagram showing an example of the driving method of the annular ultrasonic motor of the invention, and Fig. 3 is a diagram showing the conventional annular ultrasonic motor. A cutaway perspective view of the motor, Figure 4 shows the radial direction 1 of the annular ultrasonic motor.
Figure 5 is a plan view showing the shape and electrode structure of the piezoelectric body used in the ultrasonic motor shown in Figure 3. Figure 6 is a diagram showing the vibration mode and vibration displacement when using the following vibration modes. FIG. 7 is a cutaway perspective view of an annular ultrasonic motor in which a protrusion is provided on a vibrating body. 7...Elastic body, 8...Piezoelectric body, 9...
... Vibrating body, 10 ... Convex part, 12 ...
...A moving object. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1 Figure B Figure C

Claims (1)

【特許請求の範囲】[Claims] 　圧電体を交流電圧で駆動して、該圧電体と弾性体とか
ら構成される振動体に弾性振動を励振する円環形超音波
モータにおいて、前記弾性体に少なくとも０〜１／４か
１／２〜３／４波長間あるいは１／４〜１／２か３／４
〜１波長間のいずれかに凸部を設け、一方の回転方向で
はｎ波の弾性振動を励振し他方の回転方向では、ｎ波以
外で、しかも、一方の回転方向の前記凸部の振動軌跡が
反対方向となる整数波の弾性振動で励振するよう分極処
理された前記圧電体に電圧を印加したことを特徴とする
円環形超音波モータ。In an annular ultrasonic motor that drives a piezoelectric body with an alternating current voltage to excite elastic vibrations in a vibrating body composed of the piezoelectric body and an elastic body, the elastic body has at least 0 to 1/4 or 1/2 ~3/4 wavelength or 1/4 to 1/2 or 3/4
A convex portion is provided at any point between ~1 wavelength, and in one rotational direction, n-wave elastic vibration is excited, and in the other rotational direction, vibrations other than n-waves are excited, and the vibration locus of the convex portion in one rotational direction. 1. An annular ultrasonic motor, characterized in that a voltage is applied to the piezoelectric body which has been polarized so as to be excited by integer wave elastic vibrations in opposite directions.