CA2075032A1 - Piezoelectric motor - Google Patents

Abstract

A piezoelectric motor comprising a stator (1) with a piezoelectric oscillator and a rotor (2), the piezoelectric oscillator having a piezoelectric element (12) with electrodes (13), and pushers (15). Each pusher is provided with a spring (16) by means of which it is arranged on a collector (18, 19) being mounted on the body coaxially with the piezoelectric element (12). Each pusher by one end keeps mechanical contact with the piezoelectric element (12) under the action of the spring and by other end abuts a surface of the rotor at an acute angle. The springs of all pushers may be orientated in one direction circumferentially or in opposite direction (for adjacent pairs of pushers). Furthermore, to allow a reverse of the motor, the pushers are divided into two groups, in each group the pushers contact the surface of the rotor in opposite directions.

Description

, lu~7~ ~'Cl/~ 0X~)7 ~S~
PIEZOELECTRIC MOTOS~

tSpeci1catlon) .

FIELD OF THE INVI~NIION

The pres~ont lnventlon relates to plezoelectrlc devlcesand, more partlcularly, to plezoelectrlc devices of a preferably rotational movement type. A motor may be us~d as a low-speed gearless drlv~ of diferent meohanls~s such on~s t as tape transport mechanlsms of tape-recorders, lnput-output apparatus, alpha-num~ric prlnters perlstal~ic pumps o~ ~ `
medlcal usage, ln an automotlve lndustry as drlves o windscreen wlpsrs, glass-fram~ rlsersand others.
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PRIOR ART `
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lS It is knoun a piezoelectrlc ~otor (US patent ~' 3211931, : . .
- US. C1~10-8.3, published October 12, 19S5) comprlsmg a :~
statlonary mounted pie~oelectric osclllator of t~rsional .
vibratlons whlch is a cylindr~cal element made of .
plezoelectrlc ceramlcs and polarlzed ln a speclflc mannsr, wlth electrodss provlded on hls end sur~aces and a drlv~n element a rotor b~lng rotatlonally mounted ln allgnment wlth hlm. on ~re~ ends of the ple~oelectric element are fi~ed pu3hers the free ~nd o~ whLch are bended-off and lnteract `.
wlth a ~ur~ace of the rotor at an acute angle. When applylng an alternatlng voltage to the elect~odes ~f the osc~lator :.
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the free ends o~ hollow cyllndrlcal ple20electrlc elements supported as a cantllever perform torslonal vlbratlo~s ~ln a circumferentlal dlrectlon). Ihese vlbratlons are transeormed through the pushers lnto a unldlrectlonal rotatlonal ~ovement of the rotor ln a manner llke that which takes place in a ratchEt-and-pawl ~echanism.
A drawback of the abo~e piezoelectrlc ~otor ls ' , slgnlflcant dlmenslons of the p1ezoelectrlc ele~ent (the length of tne cyllnder) stlpulat~d by necesslty , to obtaln ,' angular displacoments of tho fee ends of the-plezoel~ctrlc element to be sufflclent or the oparatlon of the ~otcr.
To overcome such draubac~ ln the plezoelectrlc motors are used the osclllators ulth piezoelectrlc elements made ln ' orm of a solid dlsk or a rlng wlth electrodes and polarlzed '15 ln such a manner that when applylng an alternatlng voltage , ~ ' to the electrodes radlal vlbratlons take place ln the plezoelectrlc element.
It ls known a piezoelectrlc motor ~USSR. A.C N ', 1278994, Int. Cl. H 02N2/00, flled July 5, 1974, publlshed December 23, 1986) comprlsing tuo coaxlally mounted cyllndrlcal elements one o uhich s made o a plezoelectrlc actlve material with 21ectrodes, and pushers, each pushsr belng fixed on one of the above elements made of a ~ pie20electrlc non-actlve material at an acute angle with lts -~ ~ 25 surface: a free end of the pusher lnteract-~ wlth a surface o~ other element made o~ a piezoelectrlc actlve materlal also at an acute angle wlth lts sur~ace. On the sur~acs o~ ;
the cyllndrlcal el~men~ mdde Oe the pl0zoelectr~c ~ct~ve ,' ' materlal tnteract~ng wlth the end~ o~ the pushers ls coated 3û a uaar-reslstant layer acoustlr~ally coupled ~lth the '~ p~ezoelectrlc element.
-; , When applylng an alternatlng voltage to the electrodes--,~ o the plezoeleCtrlc element ln the last take place rad1al ' t, Yibrat~ons, and durlng lnteractlon of the surace o the -35 plezDelectrlc element ulth pushers orlglnates constant ;~
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~orque s~ttlng tha motor ln rotatlon.
A drawback of the above motor ls a necessity to apply a wear-r~515tant layer on the surface of the plezoelectrlc elem2nt lnteractlng ~iCh the pushers since, ~lrstly, the 5 presence of such layer results ln a partial absorptlon o~ -acoustic vibratlon energy of thq plezoelectr~c element re~uclng the motor e~ficiency and, secondly, ls the reason o lou rellablIlSy s~nce a breakdo~n of coupllng of the layer wlth the plezoelectrlc element puts the motor out of order. Moreover, upon wearing the above layer 1t ls requested to change an osclllator assembly.
It ls known a plezoeie~trlc motor t~ritish patent - applicatlon N 2I18374 A, Int. Cl. H 02Nll/OO, published October 26, 1983) comprlsing a stator, a rotor frictlonally 13 lnteractlng wlth the stator hav~ng a body, a plezoelectrlc oscillator of radial vlbratlons being mounted on the body and cOmprLsln9 a plezoelectrlc element mounted coaxlally ulth the rotor and made ln form of a dlsk ~a ring) wlth electrodes and, at least, two pushersi each of ~hlch ls flxed ~`
by one end on cyllndr~cal surface of the plezoelectrlc . .element uhlle by other end abuts the rotor. The pushers are fixed on the plezoelectric elements by two ways:
al dlrectly ln a materlal itself in grooves on a perlphery of t~e piezoelectrlc element ~for example, w~th '5 help of glue): `
bl on a ring-caslng belng placed on outer slde o the ~`
pie24~1actrlc alemqnt: a tlghtness of connectlon o~ the rlng-cDslng ~lth a materlal o the plezoelectric element ls achieved by usage of a ~orced ~lt of by so~e other way (for ~;g 30 example, by a glue fixlng ~he r~ng on a cyllndrical slde surfac~ Tha pushers ars flxed to such rlng or rad~al slots by m~ans of solderlng, or by ~elding to its outer surface.
Draubacks of the at~va piezoelectric motor result from a manner o ~lx~ng the pushers to the plezoelectrlc element i3 and are the follo~lng:
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a) Flxlng of pushers directly ln the materlal of the plezoel~ctric element reduces dlmenslons o~ an active region of the element slnce d clrc~lar portlon of the plezoelectrlC
element ln whlch one are made radlal slots for placlng pushers ln act proves to be passlvo one:
b~ Flxlng of pushers in radlal slots on a perlphery of the plez~e}ectrlc element wlth help of dlfferent solders, .~
co~pounds ls a mechanically non-reliable uay: moreover, the .-presence Oe such materlal to be dlferent from a materlal of - .
the plezoelectric element ln respect of physlcal propert~es be~ween pushers and the plezoelectric elennent teven ln form .:~
o a thin layer) detariorates a transmission Oe vlbratlons from the plezoelectrlc elements to pushers reduclng the apparatus ef1clency:
c) ThP slots ln the ple~oelectric elenlenL for flxlny oL
pusher~ ~n operational mode of the piezoelectrlc element are the ~ourre of the mlcloclacks causlng the break-down of th~s element herewi~h reduclng an operatlng resource of the plezoelectrlc motor:
2~ 0 A u.~age of an outel- Irletallic rlng as ~n internlediate elemenL for mountln~ l~ushers conl~ cates a pinL, Ina~es It non-re]iable:
- when asse~blln~ by a Eorced fil. t~,e OU-~I rlny on Lhe plezoelectric element ln l.he last origlnate ln~ernal '5 stresses~ This leads to reductlon of the nloLor eflc~ency slnce a part o applled electrlcal energy ls consumed or compensatlon ot a rlny resls~ance and as a result ~s unnecessarlly dlsslpatad ln form Oe heat lncreaslng a temperature ot a worklng bo~y of the motor. Arlses, 30 moreover, dl~flcult to be solved problem of a ~electlon of a ~
rlng materlal possessing an agreed wlth plezoelectrlc --ceramlcs value o a coe~flcient of thermal expansion as we as necessary elastclty and flexlbillty;
- connrx~lon of the outer rlng on uhlch are flxed the pushers wlth the plez~electrlc element by means of glue, '' .

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~ J ~ U~i4 ~ 1/U~V7 2~7~J~'32 _ 5 _ solder (or other compound~ lntroduces an lnter~ltten~ layer deterlor~tln~ a trans~Lsslon of vlbratlons from the ple~oelectrlc elsment to pushers reduc m g thus the apparatus eflciency.
5tatlonary 1xlng~ ~oreover, of pushers on the plezoelectrlc element lor a rlng) narrows unctlonal and te d nologlc~l Q pablLItles ~or ~btainlng motors r,e one ~$andard slze wlth ~fferent r,t~aracterlstlrs (a rotatlonal speed, a shaft torque and so onl.
Therefore the fl~st aLm of t~e lnvention ls to lncre~se rellabl11ty and economy o~ a plezoelectrlc ~otor as ~éll as . ~ :
to ulden functlonal rapabllltles due to lncreaslng a degree of unlficatlon. ,, -- It ls the second alm of the lnvention to slmpllfy and ~ `
lS to reduce dimenslons o~ the plezoelectrlc motor.
One more drawback of the motor ln accordance with the patent applica Uon N 2118374 A, as well as others cases ' mentioned above is a unldlrectlvlty o~ rot~tlon stlpulated ~ by flxlng all pushers ln thelr lnvarlable lnclined positlon- 20 to the surface of the ~otor.
' It is known, however, a plezoelectr~c motor of a -~
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reversible act~on - Sueden patent appllcatlon N 45293~, Int.Cl. H 02 N2/00 flled Apr11 5~ 1982 and publlshsd O~tober 6, 1sa3. The motor comprlses two coaxlally mountsd plezoelectric element~ wlth electrodss ~nd pushers. one of the plezo~le~trlc elements ~s mounted statlonary on a stator, whlle th~ other - o~ an output shaft, hereulth an ~lectrlcal contact of electrodes of movable plezo~lectrlc olemqnt ls reallzed ~ith help o sllp-rlngs and brushers.
.~ 30 Ihe pushers on the plezoelR~trlc elements are bent to onej slde and lnteract wlth lntermedlate rotor ln form Oe a cylLnder.
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When applylng an alterr~tlng voltage to electrodes of statlonary plezoelectrlc element its pushers turn the .:
lnter~ediate rotor and further the output shaet Ulth movable .- ' .. -' ~: ~ 5~ STJTIJTE~ SHE~ll . `

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ple2~1ectrlc element through the actlon of hls pushers t~ended ln the dlrection of movement of the lntermedldte rotor. When app1ylng a voltage to electrodes of movabl~
plezo~lectrlc element the pushers interactlng wlth S sta~lonary lntermedlate rotor be~ng braked by pusher~ of statlonary plezoelectrlc element turn movable plezoel~ctrtc element ulth output shaft ln an opposlte dlrection. ~hen the voLtage ls absent on both plezoelectrlc elements the motor 1 c braked.
Drawback of this motor - a complexlty of d structure slnce lt comprlses a second piezoelectrlc slement, -sllp-rlngs and the lntermedlate rotor as well as a llmlted torque since a passlYe group transf errlng th~? torque operates as a frlctlon coupling.
Therefore it is the third alm of the lnventlon to provide a reverse Oe the plezoelectric motor.

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DISCLOSURE OF THE INVENIION
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AchiPvement o~ the ~irst alm of tlle lnventlon provldes for creation o~ a plezoelectrlc motor of such deslgn 25 lmplementation whlch could allou, dlle to detachable connectlon of pushers wlth a p1eæoelectrlc element,to lncrease relldblllty o a motor ~hls operatlng resource), an economy ~an efCiciency) as well as to wide~ ~unctlonal capabllltles of motors due to lncrease of a degree o~
30 unlflcatlon.
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The flrst aim of the lnvention is achleved by the fact that a pleoelectrlc nJotor comprislng a stator, a rotor frlctlonally lnteractlng ~ith the s~ator htavl~tg a body, a ple~oelectrlc osclllator of radlal ~lbratlons ~elng ntounted 35 on the body and comprlslng a ~ oelectrlc element mounted ~, ' SI~EISTITVTE SJ~E~T ~: ~

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co~sxidlly wlth the rotor and made in form of a dlsk or r~ng wlth electrodes, and pushers ea~h of whlch by one end mechanlcally contacts the plezoelectrlc element and by o~her end - cont~cts the rotor at an acutz angle to lts surface, 5 ln accordance with the present inventlon addltionally comprlses a collector made ln f orm of a rlng ~lth seats and fi~edly mounted on the body coaxLally with the pl~z~lectric element, the pushers are provlded wlth sprlngs by means of uilich the pushers interac~ w}th the collector (are fixed ln 10 the seats of the collector).
E~esldes, ln accordance wlth the present invention the ~
sprlngs of pushers are orlentated ln one directlon ;`
clrcumferent.lall~ . -ln accordance .ith the presen~ inventlon the sr~rings of l5 ad~acent pushers are orlented, moreover, circumferentially in opposl te di rectl on.
The presen~ lnventlon cherac~erlzed also ln that each palr of ad~acen~ pushers is provided with one doubled sprlng. ~-Here~lth, In accordance uith the present ~nventlon Lt,e 20 springs of the pushers, belng a sil-gle pusher or comblned ones lnto the pair of the pushers, are made ln form o~
bended portlons of pushers plates.
The present invention charac~erlzed, moreover, in tna~
the palr oE the ad~acenl: pushers is ll-shaped and provided 25 wlth addltlonal sprlngs made in form of d palr oE
. s~mmetrically bended plates ~t- o slngle ones or comb~ned `
lnto the palr~ arranged between the ad~acent pushers.
The presenL lnventlon allows to lncrease relldblllty oE
the plezoolectrlc motor due to excludlng permanenC
30 connectlons of th~ pushers wlth ths plezoelectric element, ~o increase hls e~f~clency, maintalnabillt~ ~due to ~nrrease of modularlty o structures~. -~ esldes, the presenL lnventlon allows to produce - plezoelectrlc moLors wlLh unlfled structure components - -3~ p~e~oelectrlc elemzn~s (osclllators), unlts of pushers ''''' "~

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possesslng dlferent characterlstlOE wlth unlfled dimensions that wlll allow to wlden characterlstl~s range o~ motors.
Achlevem~nts of the second alm of the lnventlon provldes ~or creatlng of a plezoelectrlc motor wlth such 5 structure performanca ~hich ~uld allow, because of uslng a collector - wlth elast1c teeth-sprlngs, ~ixlng pushers on the surface of the piezoelactr~c element, to slmpllfy the motor, reduce his rad1al dimenslons, lncrease rellablllty.
The second alm of the lnvention ls achieved by the fact 10 th~t ln a piezoelectrlc motor ln accordanc2 wlth the irst vat lant comprlslng a rotor, a stator wlth a ple~oelectrlc element and a rlng coll ector placed between the plezoelectr~c element and the rotor and havlng pusher~
belng fixed on lt by mean:; of fasten~ng sprlngs the l; collector ln accordance wlth the present invention is made In form of a set o Leeth-sprlngs elashcally pressed to the p~ezo~31ectl ic element and mounted on a plane met alllc rlng belng p]aced on the stator parallel to the pi~zoelectrlc element, the fasten1rl9 springs of pustlers ar~ arranged ~0 t)etween the piezoelectrlc element and the teeLh- sprlngs.
~esides, the pushers in accordance ~A~it.h thf: lnvenLion ~`
are n-shdped and U~e~ r cor~nectors are arranged l~e~ween the plezoelectrlc element and t~le ~eeth-sprl7lgs o~ t he - collector, ~5 Achlevenlent o~ the thlrd alm oE the lnventlon prov~de~;
;~, for creatlon o a plazo~ler trlc motor wlth sllch structure, performance wh~Ch could allow, bac~use ot uslng two groups of pushers whlch are mountad non-unlrdlrectively ln respect to a surface of a rotor and capable to interact alterndtsly ~0 wlth the motor, t~ reverse the motor.
.- The thlrd alm of the ln~enLion lS achisved by the fact ~= that ln a plezoelacts~lc motor comprislng a stator, a rotor ;
-- frictionally lnteractlng with the stator haYlng a bodv, 3 -~ plezoelectrlc oscillator o radlal vlbratlons belng mounted :
35 on the body and ccml~r1s~ng a plezoelectric eiement mounted ' --- - ` SWBSTITUTE SHEET

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coaxlally wlth tha ro~tr and made in orm o d disk wlth elzctrodes, and push~rs e~tch of whlch by one end m~chanlcally contacCs the piezoelectr1c element and by other end - lnteracts with the rotor at an acut~ angla, in accordance ~ith the present inYentlon the pushers are divlded Into equal groups, ln eac~t group the pushers contact the surface o the rotor at acute angles ln oppos1ts dlrectlons, the motor addltlonal1y comprisr-s dogs arranged between the pushers cirumferentlally and movably for lnteraction wlth the pushers, 1.e. or puttlng thus the pushers out o contact ulth the rotor.
Herewith, ln accordance with the present lnvzntlon the i !:
dogs ~ncerac~, In ultlmate positlons, with the pushers of one of two groups of pushers puttlng them out of contact 15 Wlth the rotor. ~ , Besldes, ln accordance ~lth the present inVentlon the dogs lnteract sLmultaneously ln central tneutral) posltlon, with the pushers o both non-unidirectlvely orlented groups - putt~ng them out of contact wlth the rotor.
~he presen~ lnvent~on allows to provlde a revzrse o~
the p~ezoelectrlc mo~or due to alternatlve putL]ng lnto contact ~lth the surface of the rotor the~non-unld~rectlvely or~ented groups ot the pushers: besides, due to slmultaneous contact of both groups o the pushers ~n central positlon ot '5 the dogs, may be provlded a f~xation of the motor ~hen lt swltched off, l.e. braklng ln a definite posltlon of the ntotor and a machanlsm being coupled ~lth it.
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, 30 ~RIEF DESCRIPIION OF THE DRAWINGS

he present InYentlon ls clarifled by concrete euamples of lts amtx}dlment and the a~companylng drawings and where~n: -~
. ~ Fig.l shows a f~rst Yarlant of a plezoelectric motor ; `~
ith a cylindrlcal ouCer rotor smbracing pushers which are ..,. -.
. -2~ 32 pressed to h~m ln accordance wLth ~ E~rs~ alm of the Lnventlon, and a lon~ltudlnal sactlon n-n Ot Flg.l;
Flg.2 shows a piezoelec:tric motor, a cross-sectlon along a llne I-I of flg.l ln accordance wlth the lnvention:
Flgs~a, 3b show a pushar with a fastening sprlng made ln ~orm of a bended end of a pusher plate ln accordance ulth the lnventlon:
Flgs4a, 4b sho~; a pusher ith fastening springs made in orm o oended cut slde edges of a pus~er plate in accordance wlth the lnventlon: -FlgsS and 6 show doubled pushers, with fastenlng sprlngs made ~n orm of ~ended nllddle pdrt of pushers plate `
in accordance with the lnvention;
Fig.7 shows a doubled pusher fasten~ng springs of whlch la are made lndependent ones ln accordance wlth the lnvent~on;
Figs.8a - 8e deplce varlants of emtodlment of one o~
two fasl enlng sprlngs of the doub~ed pusher shown ~o Flg.7 ~n accordance with the lnvenelon:
Figs.9a - Sld deplct varlous klnds of flxlny slngle 'O pu~hers ~n accordance wlth F~gs.3a and 3b and doubled pu~hers ~n accorslanc~ ~iLh Figs.5,6 and 7;
Figs.lOa and lOb deplct a varlant o~ f~x~ny ~he doubled pusiler ln accordance InLh Fig.7;
Flg.11 show fl.~ng the double~l pusher ln a S ple~oelectr~c motot wlth an ouLer rlng elemenl. and d rotor placed wlChln lt ln accordance wlth the lnvention:
Flgs.12a ~ 12d show one o~ varlants of structure eldm~nts Oe a collector as well as mdnners Oe f~x1ng a colleceor to a body o a pieZoelectrlc motor and cannectlng the structure memt~rs tharebetween ~n acrordance ulth the lnventlon; :.
Flg.13 shows a second varlant o a plezoelectrlc motor wlth a cyllndrlcal outer rotor embraclng pushers wh~c~h are pressed to him ln accordance ;ith the second alm of the 35 lnventlon, a longltudinal section n-n of Flg.13:

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~ IU~7~ 5~ P~/s~9~/~n8u7 Fl~.14 shows a ple~oelectrlc motor a cross-sectlon along a llne I-I of Flg.13 ln accordance with the inventlon:
Flgs.lSa and 15b sho~ fragments of blanks of eollectors for a plezoelectrlc motor with the an outer rotor tFl~.15a) and wlth lnner or outer rotor (Fig.15b) ln accordance with `. the inventlon:
Figs.16a - 16c depict mutual location of a collector wlth a piezoelectric element ln structures with outer - arrangement o~ a rotor tFigs.16a, 16b) and inner arrangement of 2 rotor ~lg.16a);
Flg.17 shows a third varlant o a piezoelectrlc motor with a cylindrlcal ouLer rotor embracing pushers which ones - belng non-unldlrectlvely orlented are pressed to hinl and . ~. .
have dogs for interactlon with the pushers 1n accordance 1-. wlth a third alnl of the invenLion, a longitudlnal sectlon n-n of Fig.18:
F19.18 show a plezoelectric motor, a cross-section along a line I-I of Fig.17 in accordance with the invention:
Figs.19a - l9d deplct various dlagrams of interact~on - '0 of dogs with pushers in central and ultimate poslLions of -: the pushers ln accordance ~ith Lhe lnventlon:
F19sO20a - 20e sho~ on~ of posslble varlants o~ a de~ice for turning a rlng with dogs and hls ~l~atlon ln central and ultlr~ate posltlons ln accordance wlth the 25 ln~ention: ~ `
Fig.~l deplcts mutual locatlon of structure elel(lents of ,, ' ' ! ,' "
a plezoelectrlc motor with a central rotor and outer rlng-shaped plezoelectr~c element in accordance wlth the nventlon. . ":`
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J ~ '/lU~7-t 2~ P(-~5E91/00~07 DFI AILE~ DEsCRIPTION OF THE INVE~IT~ON

A plezoelectrlc motor ln accordance wlth the flrst var~ant of emtodlment ~Flgsl, O comprlses d stator I ~
5 ~tatlonary part of the plezoelectr1c motor ln respect of an artlcle (not shown ln flgures) and a rotor 2 supported rotat1-/ely on the stator 1 wlth help of a ~earlng (a bush~
3. Agalnst axlal displacement the rotor ls flxed ~n a rotor shaft 5 by means o a shoulder 4 and a lock ~asber 6.
The stator 1 of the plaZoeleCtrlC motor comprlses a piezoelectric oscillator 7 of radlal vlbrations aco~stlcally lnsulated f rom a body 8 by means o gaskets 9 of elashc materlal ~for ex~mple, rubber) and ~lxed on lL with help' of a nuL 10. The body 8 protects the plezoelectrlc osclllator 7 15 and other elenlents of the motor agalnst da~lage, as well as support the ple20electrlc motor ln the artlcle wi th help o~
astenlng holes 11.
The plezoelectrlc oscillator 7 of radlal vlbra~lons is dn elec~romechanlcal device for converslon o~ e~ectrlcal `:
20 enerqy Lo n,ec~lanlccll one of oscillatory preer~bly ~n radlal dlrecLlon, moLlon of parLicles of actlve element o~ the p~ezo~lectrJc oscillatol 7 - a plezoelectric ~lement J2 made ~n form of a body of revolu~lon. For orlglnatlng radial vlbratlons ln the plazoelec~rlc osc~lla~or 7 ~t~e '5 piezoelectr~c element 12 ls made in form o~ a flat rlny ~a desk wi~h holes) manufactur~d of a materlal poæes lng ' - ple~oelectric pro,oertles, llth elecerodes 13 on flat surfaces Oe ~he rlng provlded wlth terminals 14. 'rhe electrod~a dr~ a thln matal coatlng on a ground surl~ace Oe ` -30 tho plezoelectrl~ element 12 hlch may be obtalned, ln part1cular, by spraylng a metal, chemlcal sedlmentat~on of a -~ I metal up to nec~scary thlckn~s of slectrodes. Alternatlng ' `
voltage ~rom a po-~er source In~t shown ~n Flg.l) ls applled to the electrodes 13 through the tern~lnals 14 uhlch are 35 soldered to tha electrodes as sho~n ln Flg.l. ~The terminals may be ~onnected also by a contaFt method.) ,: .
' ' ' ,.''.. , ~3U~STIT~JTE SHEET - ;- -`~r'O ~/1()8~ PCI`/SE91/00$07 2~

Pushers 15 cont~ct outer cyllndrlcal surface of Che plezo~lec~r~c elem~n~ 12 and abut lnner surfaco o~ ~h~ rotor 2 at an acute angle ~lth oCher end. F~xing of the pushers to the body ls made ~lth help o~ spr~ngs 16 by whlch ls 5 provided each pusher lndl~ldually as shown in Fig.2 lsee also F19s3a, 3b 4a, 4b). Dlrect contact of each ends of pushers lS uiCh the surace of the piezoelectrlc element 12 wlthout lntermedla Ce blndlng mate~lals lsolder, glue epoxy compounds etc3 ellminates energy losses ln th~n layer o~
10 tha above materlals placed bacween the pushers and the surace of the plezoelectrlc element allowlng to increase the ~otor efflclency and rellablllty due to stablllty of dlrect contact of ~he pushers with the plezoelectr~c elemenc.
The pushers may comprlse a spring elemcnt 16 uhlch 15 a --part of a plaCe-blank ~hich ls bended in a specLflc manner (see Figs.3a, 3b, 4a, 4b). Ends 17 of sprlngs 16 of the pusher 15 are supported in a collector made of two structure elemenCs 18, 19 tFigs.l, 0 whlch provldes for ax~al and 'O clrcum~eren~ial fl~aClon of the pushers such fas~enlng does not hlnder ~he end of ~he pushor ~ronl a radidl dlsplacenlenL
wh~ch one dlrectly contac~s the surface o Che plezoelectr~c elen~ent 1'.
Pushers may be made as slngl~ ones tFl~s.2, 3a, 3b, d,a '5 and 4b) or doubled.
The sprlngs 16 for fast~dnlng th~d pusher~ may be made as a banded part o the plate-hlank as shown ln Flgs.3a, 3b, ~b, 5 dnd 6 or as separate parts (Flgs.7,8), In last rdse to prevent an axlal dlsplacament o~ the pushers on ends of such ~i 30 spslngs ar~ mdde slots (~lg.8b) or angles of such sprlngs are bended outward lFlgs.8c, Bd, 8e).
Each pusher ls nlade o~ flaL tsheet) elastic sound conductlng materlal, for example, of steel, trass, ;;
phosphor bronze.
Single pushers 15 1 Flgs.3a, 3b) nlay be mounCed w~th - , ~
".~
~ T1 IT~ II~T

... . - - . -, . . . . . . .. . . ..

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help of sprln~s 16 belns oriented ln one directlon as shown ln Flg2, or ln opposlte dlrectlon as shown in Flg.9a.
Examples of mountlng the doubled pushers ~Fl~5, 6, 7~ in i~`' the collector are glven ln Flgs.9b - 9d, lOa and 11.
S lo the bcdy 8 of the ple~ltelectrlc motor as assembled unit of the structure elements 18, 19 of the collector ul~h pushers ls fixed by means of several scre~s 20 ~see ~igs ` 12c, l2d~. ~he parts 18, 19 of the collector are connected - therebetween by tlghtening screus 21 ~lth washers æ:
hereulth the ends 17 of sprlngs 16 are rigldly pressed betueen flat surfaces of the parts 18, 19 that provides or fl~atlon of the pushers in an axial directlon.
To slmpllfy mounting the pushers unlt on Lhe osclllator a uedge clamp of the pushers ends b~ the parL 19 ~Fig.12a) -15 may be provided. In such a case the pushers unlt ~lLh the part 18 ls reely mounted ln the bodv 8 of the plezDelectric element and is fix~d to lt by nleans of screws 20, a~er tha~ -the ends 17 of sprlngs 16 o~ the pushers are finally clamped by a conlc portlorl o~ e rarL 19 as shown ln Fig.l.
~- ~ '0 The proposel3 dJagra~- Or fi~ng ~he pushers b! means of he sprlngs 16 n~ounr.ed ~th the ends 17 In the collector ~structure element ~6) ~ldens posslbillLles of un~flca~lon of the n,otors slnce the IlloLor lS nlade of separate ln~ep~nden~
unlts - a stator ~uth ~ ple2~electric elemenLs, a pushers unit in a collector, a motor whose parameters ~ln partlculdr~
a thlckness of a plezoelectrlc element and power accordlngly) ma~ be changed. Herewlth, ln one collector 1~
ls posslble to moun~ pushers lS o d dlfferen~ wldth corresponding to a thlckness o~ a plezoelectrlc element 12 30 slnca pushers b4ing dlfferent in ~Idth ~ay be provlded ~lth .~rlngs whose ~astenlng ends 17 hav~ equal wldth, In other varlant of embodlment of a collecLor the unlflcatlon may be --Iachleved by usage if lnter~edlate rlngs for ensurlng :~:
flxatlon of pushers havlng dlfferent wldth of the fasten~ng 35 ends 17 of the sprlngs. ~ -BSTITliTE SH~ET

'/ IU~7~ PCI/SE91/0080 7 -15- ~r,~
Clamplng Oe pushers 15 to the rotor 2 ~nd the p~fazo~ lectric el~ement 12 ls reallzed due to forc~a o eldstlc de~orm,~ tlon of pushers them~ lves. To the piezoslectrlc ` alement l? are pressed pushers addltionally by their springs 5 16. l~ls ensures ~uaranteed me~hanlcal cont~ct of pushsrs lS
ulth Che plezoelectrlc element 12 uhen the last performs :
radlal vibratlons.
To ensure un~orm medlanlcal load applled to the ple20electric element the number of pusher~ should be at -10 least tuo single ones or two doubled ~nes accordlngly at unlform arrangement of them clrcumÇerPntlalIy. `.
- Radlal clearances between thee plezoelectrlc element 12, the collector 18, 19 and the rotor 2 accordlngly and a l~dngth of pushers are caled up schematlcally ln Flgs.l, 2.
15 9a - 9e, lOa and 11; ~n reality the leng~h of pushers should . `
be less to increase lts rigldlty to lateral t~ndlng.
Herewlth the sprlng 16 of pushers should have lesser rddial dlnlenslons to prevent clrcumerentlal dlsplacenlen~ of - pushers ends interactlng with the surL'ace o~ the 3û piezoelectrlc eler,le~r,t: the~l poslt~on should be near to a tangent llne in d r~oint o contacl ot Ll~e pusher end wiU, the piezoelectrlc element.
Rol or ' o f ~he pl~oelectrlc nlotor (Flg.l) comprlses three n,dln parts - tl-~- shaft 5, d CUp 23 assembled by a ~J forced fit on i~ and a Çrlc~lonal pare - a rlng ~nsert 24 uhich flct~onally lnteracts with pushers lS. The frictlonal part ls made Oe wear-reslstant materlal: lts opqratlng sur~acq should have mln~mu~ roughness to reduce wear o pushers. Th~ sha~t 5 Oe the rotor 2 ls mouAt~dd ln the 30 bearlng-bush 3 m~d~ oÇ anti~rlctlonal materlal.
c.~
- The plezoelectrlc motor may b~ performed also wlth an lnt~ rn~l rotor, l.e. b~ placsd lnsld~ ~ rlng plezoelectrlc .~ --element~ In such case doubled pushers are made not divergent ones, as shown, for example, ln Flgs.S, 6 and 7, but 35 onvergent ones: manner oÇ thelr fixatlon and ~astenlng ~' '' .
:, St3E~STITUTE~ SHEET ;~
... . . .

~ 2~10~7~ YC~r/S E9l/008U7 2'~CJ~33~

parts do not dlefer from the wrltLen above, with the axcDptlon o a shape of the par~s ltself ~see Flg.ll).
The ple20electrlc motor operates dS follows. When applyLng to the electrodes 13 o the pie~oelectrlc S osclllator 7 an ~lt~rndtln9 voltage of the deflnlte frequency - equal ~o or approxlmdilng to the resonance frequency of longltudlnal and radial vlbratlons of the plezo~lectrlc element 12 ln the last orlglnate the longltud~nal radial vlbratlons. These vlbrat~ons are transmltted to pushers 15.
When the plezoel~ctrlc element 12 l5 extended hls surface ~oves ln a radlal dlrectlon inner ends of the pushers 15 ~hlch mechanically cont~ct the surface. Opposlte ends of the pushers belng ln the frlctional interacC-on wlth the cylindrlcal surface o~ the frlctlonal elenlen~ 2~ of the rotor 2, due to a ~edging, create on the rotor d tangentlal force (s~nce dn angle betueen the pusher and th~ llne tangerlt to the surface of the rotor is less than 90 ) that results ln turn mg the rotor through some angle.
'0 From Lhe clrcumferent~al displacemen~ of inner ends o~
: pushers 15 belng ~n a mechanlcal conLacL ~lth ~he cylindrical side sur~ce of the plezoelectrlc elen~ent 1~
hinder the sprlnqs 16 o~ pushers, by means or wh~ch ~he pushers ar~ flxed on th~ collecto~ which one lS a part o~
the st~tor, as well as Che frictlonal force between ~hen~ and the surfdce ot the plezo~lectrlc ~l~m~nt ~hlch one is also a par~ o~ th~ stator.
9esldes, a fixatlon o pushers ~n clrcumer~ntial.
dlrectlon mdy ba reallzed by the collector in whase seats are mounted pushers ~see Flgs gd, lOd).
Wh~n the piezoelectrlc el~men~ 12 is compressed inner ends Oe pushers ~5 mov0 ln a radlal dlrection to a center of the plezoelectrlc ~lement under the action of an elastlc force o as the pushers thsm6elYes and the orce o thelr 3S fastenLng sprlngs 16. More outer ends of pushers 15 .'.
; .
SUBSTI~l)TE StlEET
, . . .

'fff~ ff ff~f ~ff I/UffJff~,fU I
. ~ .

- 17 - ' ~fff fff~3~ft~
lnteractlng Wlth the surface of tho frlctlonal elemenl 24 Oe the rotor 2 for a moment lose contact ~flth the sald surface dnd pushers 15 under thfa actlon of elastlc forces stralghten , ~`~1 . : . .
:~ ~` themselves, and the ends of pushers occupy a new posltlon ln 5 the clrcumferentlal directlon of the rotor, or, because of decrease of a clamplng force of the ends (wlthout loss o contact f~lth the surfacct of tha rlctiondl fEtlement 241 and decrease of a frlctlonal forcfef accordlngly, the ends o~
pushers slip on the surface of the frictional elemant and 10 occ tpy the neu posltlon ln the clrcumferential directlon o `
the rotom ~rom a reverse turn o the rotor 2, because of actlon of frlctlonal forces between the surface of the ~' ricC~onal element and the fefnds of pushers 15 sl}ppln9 on it ln the clrcumferentlal directlon may hinder largely 15 inertial forces of a mass o thb rotor and masses; of a driven in rotahon mechanlsm belng connected with If.
. . , -Such process repeats oneff~elf at vlbratlons o the piezoelectrlc elemenL 1' and is accompanied by orlgin of constant torque sethng the roe4r 2 o thz plezoelectrlc fO moi.or In rof~ation. ;` .
A second varlanf of embodLmfent o a n~o~or wlll tfe f wrlt~en wlth me~erencff ~o accompfany~n, Flgs.13 - 16.
A plezoelectl lc motcffr In accot f~ffdnce wlth I he secfJnd arlan~ of emfbocffiment tFlgs.13, IJ.) com~ ef5 ff~flso a stator 1 and a rotor 2, a ylezoelectric elbmenl 12 and pushers 15 flxed on a collector.
The second varlant o~ f~fmtf~dlment o the piezoeflectric ;' motor dlffers etrucfAf~rdlly from the first one by tff he ~ollowlng.
~ The collector of the pflezoflff~ctrlc motor ls made ln -form of a set of tf3eth-springs 25 f~flastlcf ally pressed to a ~ ¦ ~ working cyilndrlcal surface of the piezoeflectric element 12 - ff and mounted on a metalllc dlsk 26 belng placed on thef sl ator. ;The ~ ~astemng springs 16 o pushers are arranged Iffetweenf the plezofeflff~ctrlc efl2mfenc 12 and the teeth f5 f hlch -:
-: ~ ~

~fcTlT~ffff TffF f~f ff~f F~T

.i, ov l 2~ 3~

closely press the pushers to the sure~ce of the plezo~leCtrlC elom~nt as w~ s ~lx the pushers ln clrc~lmferentlal and axlal dlrectlons.
The collector ls manu~actured o a blank 26 of elastlc sheat met~l (Eor example, o steel) havlng flgured slots ln radlal dlractlon formlng teeth 25 (see Flg. 15a). These teeth ara bended perpend~cularly to a plane of the blank of tha collector and are banded along longltudlnal axes oYer an arc o a clrcle wlth a radlus not exceedlng d radlus of the ple~oelectrlc element. ~eeth-sprlngs are also bended ln longltudlnal dlrectLon ln order a contact o~ the ~`
teath-sprlngs wlth connectors 16 takes place on mlddle ~n respect of helght of the plezoelectrlc element) part of the connector (see Flgs.16a - 16cl Teeth ~5 of the collector are provided ~ith shelves 27 ensurlng flxation of pushers placed ln space between them ln axial directlon. ~
Such collector is desiynated for a piezoelectrlc motor :;
with outer rotor: lt ls nlounted under the plezoelectrl~
- 20 element as sho~n in Flg.I3. From the piezoelectric element iL ls separated by Jnsulating pad 23.
5. The collector may ~e manu~actured of a blank in form oL
a disk ~ith teeth on lts lnner slde lsee Flg.15b). Such -collector ma~ be used in a piezoelectr~c motor as uith o~lLer rlotor ~see Flg.l~bj and wlth lnner arrdngement of the roLor (see Flg.16c~. A dlf~erence in such case }s largely ln a dlrectlon Oe bendLng of taeth-sprlngs.
In the proposed structure of flxing pushers by means o~ :
suctl collector the last functlons as sprln~s whlch reallze clamplng the pushers to the plezoelectrlc elemant wlth a gl~en force provldlng a close contact. Slnce the contact o~
pushers with the ple70electrlc element is realized wlth help ~:
o the connector 16 havlng a large contact stresses ln a materlal of the plezoelectrlc element are reduced. Usage o such collector allous to reduce radlal dlmenslons o~ the '.

SUBSTlJTIJTiE S~E~

.

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motor or to lncreas~ dlmenslons Oe the plezoelectrlc alemen~
I~lth unchans~d dlmenslons o~ the motor th~t ensure an lncre~se nf motor power.
She plezoelectrlc moCor may be made also wlth lnner S rolor, l.e. the rotor arranged lnside the rlng plezoelectr~c slement 1~ In such case a rlng part 26 Oe the collector is placed under the rlng plezcsl~ctrlc element and h~s teeth clamp connects of pushers 15 to lnner cyllndrlcal surface of the plezoelectrlc element ~see FlgI6c~.
Ihe second varlant of tha plezceleCtriC moCor operates analogically to the flrst onæ~ :
As and ln tha ~irst variant o the plezoelectr1c motor ...
: rom the clrcumferentlal dlsplacement of lnnar ends of pusher lS ~lth connectors 16 belng m a mechan~c~l con~act lS wlth the cyllndrical slde surface o the piezoelectric . ---element 12 hinder teeth-springs 25 of the collector. From l .
the axlal dlsplacement o pushers hlnder shelves 27 on .
teeth-sprlngs 25 o the collector in space between ~h~ch are .~, placed pushers 15. - ~, - 20 A third varlan~ of emtK~dimenC of a motor wlll be :~ ;
wr~tten with reerence to accompanylny Flgs.17 - 21.
The thlrd varlanC o embodilllent of the plezoelectric ~ .
motor o reversible type dlffers structurally ~rom the ~irsC ... :
and the second non-reversible mators ~y the followlng.
His struc~ure dlff~rence ensure the ~act Lha~ hls pushers lS contactlng by one end the outer cyllndrlcal ;
surface of the plezoel~ctrlc elem~nt 12 abut by other end ~ha lnner sur~ace of tho rotor 2 at an acute angle ln opposlte dkectlons ormlng two non-unidlrectlve~y orlented groups.
, Besides, ln a rlng araa o the t~dy 8 bet~een the rotor -1 2 and the collector mad~ of tuo str~cture elements la-l9 are .! . . , .' provided elongated holes 29 spaced clrcumerentlally ln ~: whlch ones are arranged dogs ~O ~ount~d on a ring 31 belng movable in clrcumferentlal directlon and clamped to the body l~';TlTllTF ~ .T

- 2~ 3~ ~

8 by ~lxln~ rlng 32 whlch ls flx~d on the body 8.
The dogs 30 may be arranged on the rlns 31 ln a dlfferent, manner so that, when turn~ng the rlng lnto ultlmat~ posltlon~, the dogs band off pushers of one of the ~- i 5 groups ~ses Flgs.19c, lgd) from lnner surface of the rotor 2, whlle at the central p~sltlon of the rlng the dogs elther bend off pushers of both groupsi ~Flg~9a~ or do not lntPract ~lth pushers of both groups as shown ~n Flgsl8 and l9b.
The turn of the ring 31 may be re~al~zed from external d~lvlng means (not shown ln lgures) lnteractlng ln radlal dlrectlon, for example, with a lever 3i ~see Flg~Oa) mounted on the rlng 31.
In ultlmate and central posltlons th~ rlng 31 wlth dogs . 30 is fixed wlth help Oe ~ell known means, for example, a 15 ball 35 belng pressed by a sprlng 34 and mounte~ ln a cage ~ -36 whlc~ ls secured on the body 8 of the motor, or a 1gured sheet sprlng 37 whlch ones lnteract. w~th recesses ln the rlng 31 arrangement of whlch ones ln circumferentlal direction corresponds to glven posit~ons of the rlng an addltlonal restrlct~on to turning the r~ng above the , neces~sary rate may be realized as due to conCact of dogs 30 wi~h ~dges of holes '9 an~ due ~o stnps 38 whlch are pro-id~d on Che body 9 and interact. wLth t~e lever 33 (see `~
~ Figs.20a - 20c).
: 25 The plezoelectrlc motor may be psrfor~led as ~lth an outer rotor (see ~lgæl7 -19) and wlth an lnternal rotor, l.e. be pldced ln51d~ a rlng plezoelectric element (Flg 21~.
In such case holes 29 wlth dogs 30 are spaced clrcumeerentlally ln a rlng area between an lnner rotor 39 30 ulth a ~rlctlonal element 40 and the collector 18 - 19.
Securlng of ~he ring 31 wlth doys 30 by means o~ a flxlng - -~ rl~g 31 ln such case doesi noL dlffer ln essence from the j ~ shown ln Flgl7.
ls varlant of d re~ers~ble plezoelsctrlc mo~or 35 operates as follo~E~ :

:~ -SW~STITVTESHET ` - :-. . .. . , . .. .-.. - , . - . . . ., . . . . ~ . - .. ...

W O 9~/1087~ 2~ ~S~f3~ P~r/5E~l/oo~a7 When turning the rlny 31 with dogs 30 lnco one o~
ultlmate posltions the dogs 30 bend off a group o pushers 15 lnt~ractlng wlth them and put th~m out of contact wlth a surfac~ of tho rotor 2: other group of pwshers keeps contact S wlth the rotor. ..
When applying alternatlng volf ~ge to the electrodes 13 of the plezoelectrlc oscillator 7 the dlrectlon of rotatlon of the rotor ~111 be determlned by that whlch group of pushers keeps conf~act with the rotor.
When the r1ng 31 wlth dogs 30 ls ln the central posltlon a status of the motor wlll be determlned by a scheme of lnteractlon of dogs 30 wlth pushers 15 (see , .
Flys.18, l9b): lf both groups of pushers are slmultane~usly bended-off the motor will be swltched-off and not braked .- 15 even ln the presence of voltage on the electrodes 13; lf both groups of pushers interact simultaneously wlfh the ~
rotor tsee Flgs.18, l9a) the mo_or wlll be braked as ln the :.
ab ence and in the presence of voltage on the electrodes 13. .:
'~
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Claims (11)

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WHAT IS CLAIMED IS

1. A piezoelectric motor comprising a stator, a rotor fractionally interacting with the stator having a body, a piezoelectric oscillator of radial vibrations being mounted on the body and comprising a piezoelectric element mounted coaxially with the rotor and made in form of a disk or a ring with electrodes, and pushers, each of the pusher by one end mechanically contacts the piezoelectric element and by other end contacts the rotor at an acute angle to its surface, c h a r a c t e i z e d in, that to improve reliability and economy as well as to widen functional capabilities of the motor due to increase of a degree of unification, additionally comprises a collector made in form of a ring with seats and fixedly mounted on the body coaxially with the piezoelectric element, the pushers are provided with springs interacting with the collector.

2. A piezoelectric motor according to claim 1, wherein the springs of pushers are oriented circumferentially in one direction.

3. A piezoelectric motor according to claim 1, wherein the springs of adjacent pushers are oriented circumferentially in opposite direction.

4. A piezoelectric motor according to claim 3, wherein a pair of adjacent pusher is provided with one spring interacting with the collector.

5. A piezoelectric motor according to claim 1 or 4, wherein springs of pushers are made in form of bended portions of pushers plates.

6. A piezoelectric motor according to claim 4, wherein the pair of adjacent pushers in n-shaped and provided with additional springs made in form of a pair of symmetrically bended plates arranged between adjacent pushers.

???? ????

7. A piezoelectric motor according to claim 1, c h a r a c t e r s e d in, that to simply a structure of the motor and to reduce his dimensions, the collector is made in form of teeth-springs elastically pressed to the piezoelectric element and mounted on a plane metallic ring being placed on the stator parallel to the piezoelectric element, the springs of pushers are arranged between the piezoelectric element and the teeth of the collector.

8. A piezoelectric motor according to claim 8, wherein the pushers are ?-shaped and their connectors are arranged between the piezoelectric element and the teeth-springs of the collector.

9. A piezoelectric motor comprising a stator, a rotor frictionally interacting with the stator having a body, a piezoelectric oscillator of radial vibrations being mounted on the body and comprising a piezoelectric element mounted coaxially with the rotor and made in form of a disk or a ring with electrodes and pushers, each pusher by one end mechanically contacts the piezoelectric element and by other end - interacts with the rotor at an acute angle to its surface, c h a r a c t e r i z e d in, that to allow a reverse of the motor, the pushers are divided into two groups, in each group the pushers contact the surface of the rotor in opposite directions, the motor additionally comprises dogs arranged between the pushers circumferentially and movably in circumferential direction for interaction with the pushers.

10. A piezoelectric motor according to claim 9, wherein at ultimate positions of the dogs the pushers of one of the two non-unidirectively oriented groups accordingly are put out of contact with the rotor.

11. A piezoelectric motor according to claim 10, wherein at central position of the dogs the pushers of both non-unidirectively oriented groups are put put of contact with the rotor.