CA1228096A - Axially contractable actuator - Google Patents
Axially contractable actuatorInfo
- Publication number
- CA1228096A CA1228096A CA000467704A CA467704A CA1228096A CA 1228096 A CA1228096 A CA 1228096A CA 000467704 A CA000467704 A CA 000467704A CA 467704 A CA467704 A CA 467704A CA 1228096 A CA1228096 A CA 1228096A
- Authority
- CA
- Canada
- Prior art keywords
- enclosure
- actuator
- network
- links
- tension links
- 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
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/08—Characterised by the construction of the motor unit
- F15B15/10—Characterised by the construction of the motor unit the motor being of diaphragm type
- F15B15/103—Characterised by the construction of the motor unit the motor being of diaphragm type using inflatable bodies that contract when fluid pressure is applied, e.g. pneumatic artificial muscles or McKibben-type actuators
Abstract
AXIALLY CONTRACTABLE ACTUATOR
ABSTRACT OF THE DISCLOSURE
An actuator has a first connection point and a second connection point at opposite ends and is contractable along an axis extending between the connection points. The actuator has at least one hollow enclosure with an opening for admitting a pressurized fluid. A
simultaneously radially expandable, axially contractable constraining means cooperated with the enclosure. The constraining means converts radial expansion of the actuator into axial contraction when pressurized fluid is comprises a network of non-stretchable, flexible tension links.
ABSTRACT OF THE DISCLOSURE
An actuator has a first connection point and a second connection point at opposite ends and is contractable along an axis extending between the connection points. The actuator has at least one hollow enclosure with an opening for admitting a pressurized fluid. A
simultaneously radially expandable, axially contractable constraining means cooperated with the enclosure. The constraining means converts radial expansion of the actuator into axial contraction when pressurized fluid is comprises a network of non-stretchable, flexible tension links.
Description
~' -1-BACKGROUND OF THE INVENTION
The invention relates to an axially contractable actuator particularly suited for robotics applications.
Robotics technology is f re~uently presented with the problem of mimicking the function of human hands and arms. Mechanical analogies to hands and arms clearly must include some replacement for the many human muscles used to f lex and move the human f ingers, hands and arms. When fluid power, either hydraulic or pneumatic, is used in robotics, a f luid cylinder appears to be a likely substitute for human muscles. However, high pressure f luid requirements due to limited fluid cylinder size and space and positicr.ing problems complicate the use of fluid cylinders or make their use impossible for some applications such as in self-propelling walking robots.
Fluid c~linders are also not entirely suitable as actuators in the food and drug industries. Restrainers must be used to contain dripping caused by leaking seals and misaligned cylinder rods.
SUMMARY OF THE INVENTION
According to the invention, an actuator has first connection means and second connection means at opposite first and second ends of the actuator respectively and is contractable along an axis extending between the connection means. The actuator comprises rneans actuated by the actuator being connectable to the connection rneans. The actuator comprises at least one hollow, flexible enclosure having an opening for adrnitting a pressurized fluid. A constraining rneans extends about the at least one enclosure for converting expansion of the actuator transversely to the axis into contraction along the axis when pressurized fluid is admitted into the at G ~P
~ -la-least one enclosure. The constraining means comprises a plurality of non-stretchable, flexible tension links intersecting to form a tubular network with meshes having four or more sides. The links are connected together at intersections of the network and are arranged so the links approach alignment with the axis when the enclosure is extended and so the meshes open up when pressurized fluid is admitted to thc? enclosure.
According to another aspect of the invention, a fluid operated actuator has expansible enclosure means having a longitudinal axis, and an axially elongated state and an axially contracted state. This fluid operated actuator also includes means for admitting pressurized fluid into the enclosure means for shifting the enclosure means between the states. The fluid operated actuator further includes constraining means disposed about the enclosure means and comprises a plurality of tension links connected together at a plurality of nodes which provides a network having a plurality of open mesh areas. Each of the mesh areas has at least four sides provided by the associated tension links and the tension links of each mesh area are substantially aligned generally in parallel with the axis when in the elongated state. The tensio links of each mesh area are disposed at a substantial angle to each other when in the contracted state and the enclosure means bulges outwardly through the mesh areas when in the contracted state.
A further aspect of the invention provides a fluid operated actuator assembly comprising an expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state. Tt-e assembly includes means for admitting pressurized ~ id into the enclos~lre means for shifting the enclosure means between the states. The assermbly ~urther incl~c~es constraining means disposed about the enclosure mealls and comprises a plurllity of tension links connected tog~ther ~l ~'2~ 9~
-lb-at a plurality of nodes, providing a networ~ having a plurality of open mesh areas. Each of the mesh areas has at least four sides defined by the associated tension links. The tension links of each mesh area are in general alignment when in the elongated state and the tension links of each mesh area are disposed at a substantial angle to each other when in the contracted state so that the open area of the mesh areas is larger in the contracted state than in the elongated state. The enclosure means bulges outwardly through the mesh areas when in the contracted state.
A still further aspect of the invention provides a fluid operated actuator comprising an expansible enclosure means having a longitudinal axis and an axially elongated state and an axially contracted state and includes means for admitting pressurized fluid into the enclosure means for shifting the enclosure means between the states. This actuator further comprises constraining means disposed about the enclosure means and comprising a plurality of tension links connected together at a plurality of nodes to provide a plurality of open mesh areas. Each of the mesh areas have at least four sides, the sides of each mesh area being substantially aligned in parallel with the axis of said enclosure means when in the elongated state. The sides of each mesh area are disposed at a substantial angle to each other when in the contracted state. The enclosure means may be non-elastomeric a,nd bulge outwardly through the mesh areas.
BRIEF DESCRIPTIOM OF THE DRAWINGS
Figure l is a side view of an actuator, according to an embodiment of the invention, in a pre-installation state;
Figure 2 is a side view of the actuator of Fiyure l in an axially uncontracted state after installation on a hinged arm;
g6 Figure 3 is a fragmentary view of an alternative embodiment having a network with six-sided meshes;
Figure 4 is a side view of the actuator of Figures 1 ancl 2 in an axially contracted position aft:er installation;
Figure 5 is a diagrammatic side view illustrating in sirnplified form the function of the network of the actuator of Figures 1 - 4;
Figure 6 are diagrammatic perspective views to 8 illustrating in simplified form the function of the actuator of Figures 1 - 9;
Figure 9 is a perspective view, partly broken away, of an ~G
b947/198 s~
actuator according to anothf?r r?mbooiment of the IIIV~ tiOII;
f lgur(~ 10 l9 ~ll r?xplodf?d pf?rl3pf~c~vl? ~ w of tht? t~tu~tor of Flgure 9;
Flgure-~ 11 is a pl~r~p~r:tivr? V~l?W of tht? fr~ction r~duclng layl?r of the actuator r f F~gurl~9 9 all(l 1(I;
figur~? 12 i~ a pf?rspf~ctivr? YleW of tht~ ela~tolnt?ric t?nclo8ure of thr? actuator of FigurH~ 9 to 11;
Fi9Ur~? 13 i9 a SHCtlO(I~I ViHW alollg linf? 13-13 of Flgurt? 11;
15 Flgure 14 i3 a sldB vicw of ~l~ actuator accordlllg to a further embodimclIt of th~? inVt?lltlOn in all axially urlcontracted 9tatt?;
FigurH 15 i9 ~ Sidt? view of tht? ~ctuator of E19Urt? 13 Ill a~ ally co~ltràcted stat~?;
f l9urt? 16 is a 8t?Ctioll~l ViHW alollg llrlt? 16-16 o f F l9urf? 15; ~lld Fl9urH 17 ls a 9Hctional vlr?w alorlg lillt? 17-17 of ~ Igure 14.
C)ESCRIPTION OF THE PRE~ ERRED EMBODIMENTS
Fl9urr? I illu8trat~s an actuator I accordlng to ao ~?mbodimsnt of thr? illVCIItiOII. Tht? actuator has a hollow t?nclosurt? 2, in thls 30 C~i9B of an etastorlle?ric material. In othsr embodirnellts a plurallt~ of cllclosures could bB us~?d togf?ther ill p~rallF?I. The ~?rlclosurr? may br? madt? of rubb~?r, syrlthr?tlrc rubbBr or a suitable t?laatomBric plastic matt?rlal. Thf?
r?nclo8urr? i~ ClOSf?d at a flrSt f?lld 3 Wht?rr? lt l'S bolldt-d abollt a thrt-ad~l st-ld or bolt 4. Tht~ ~3tud 4 provld~?s conllectloll me ll~8 for conllf~ctlll9 th~
s~
actuator to a mounting bracket 8 as ser n in Figur~ 2. The stud 4 IS
conrlected to thH bracket by 8 pln 10. The mounting bracket i9 conllected tD
an articulated arm 39 by a bolt and nut comblnatiorl 14.
Ihe ~nclo~ur~ has a ~ecolld end 16 whlch 1~ opell in th~t it 18 bonded about 8n Operl ended nipple IB. The nlppl~ h~ a thr~3adf!d outer erld 22 adapted to enlgage a fitting 24 of a hose 26 a~ shown lo F~gure 4. In this manrlr~r prssr~uri~0d fluid, such as hydrHulic fluid or pressurized air, can b~ admitted into the open snd of the enclo3ure. The nipple is conllect0d to ~
10 bracket 23 by a nut 25 and thereby comprises a secolld conrlection means of the actuator. Brucket 23 is mounted on th0 arm 39 by a nut and bolt combination 27. The bracket and arm servH as an exHmple only of msans actuated by the actuator.
The actuator has a network 28 of no~ trr~tchable, flexiblH tension link~ 30 extel)d~ng about the enclo~ure. The links may be, for example, flexibl~l braided w~rH covered with plastic. A plurallty of ~uch wires are connected together at node~ 32 to form the es~entially tubular nHtwork. Alternatively the llnks may be of other materialA s-Jch as ~ylon 20 twine. The network has u first end ~4. Similarly, the network has a secolld erld 36. At Hnd 36 the wires comprising the network pas~ through ~ plurallty of apertures 35 extelnding through a ring 20 and extendirlg circumfererltially about the ring. The ring fits over nipple 18 snd butts ag~dinst end 16 of th~
enclosure. Knots ~7 s~re formed on the ends of ~he wires to retairl the ellds of the wires on the ring. In a similar manller, end 34 of the network 28 Is colmeoted to ring 6 fitted over stud 4.
In referrillg to the actuator, axi~l dimerlsiorls and directions extend alorlg longitudirlal axis 38 of F~gurH 1 extendirlg betwE~e 30 the erlds of the erlclosure. Transverse dimerlsiorls and directions are perperldicular to thbs axis.
Figure I illu~tratss the actuator in its prH-installation or off-the-shelf collditloo. 1'ht! ellclosure 2 IS uustretched a~d the l~etwork 28 fits 1008ely r?boUt thf` (-`I~ OSUrf' IrI .I bag-llke ,na~ er. As may be oL?sr rved, tht~rl1 I? C0119lderi;~bl(1 9paCI` betwt~ell the llntwork aoc1 the f~uclos-lrt exct l)t at the ellds 54 alld -S6. It mr,y ulso br~ ot)served from F~lgurfls I alld 4 th~ the rletwork has rneshes whlt h ar(? Iarger ul-?<?r the cellter of the lletwork to flt the shapf? ofr th~- r xpc,oded f~rlclosure. Thr? mitshes are progresslvt?l~ smaller towards the two nuds of the ellclosur(:.
Flgure 2 IllusLriites the a3ctuator Irl call extr odt~(l, Inlt.l.?l collditlol~. Io this case, the el~closure hr~is bet-~l axlrilly strf tchr-d ul~tll the lletwork fits closely abouL the 0rlclosure~ Thls e3 the axlally ullcolltracted statf- oF the aettiator after lostallatiorl orl the arm 35' wlth a hl~lged or artlculated jolrlt 41. The Inltial tells~orl rt3quired ~o mail~ttilo th~s ullcolltracted at~ite is provlded by ,--, we~ght 43 conllf?cted to a bolt 45 oi~ thr-el~d of thf? arm.
lu order to corltrrict the uctu~itor e.ixliilly~ pressurl~ d3 fluid Is adrnitted illto the erlclosure by hose 26 as Illustrated ~u Flc~urf 4.
Thf? pressurizHd fluid radmitted irIto the r~r.closurt-3 Cf~U9tlS r~idec?l eXpriII9I011 ~?S
showll ~r~ Figurt? 4 where tht~ r llclosurft bulges most prorn~nelltly ~?t the m~d-2i9i poillt betw0ell its two el~ds. The lletwork acts as eollstrr~ g mearls wh~ch Is, at the sam0 time, rad~ally expsl~r'iable, but eixlally cootractablP. Thc wlrt-s or otht?r tt?llsiOIl lirlks cornprislllg thts? Ilt?twork i~rt? r sstllltl~311y Uoll-strt-~cihahle. Coosequel~tly thc radisl expailsloll of the rle~twork, rausr-~t-. hy the radir~l exp~illsloll of the ellclosuri?, must be taccompanlf3d t-~ ax!ril cootrt,ctioll of thi? a-ictuator r~-is may i.?~? observr?d by comparll)g f Igures 2 ao 4. Irl ~I)e extelldcd cooditioll o~ 1 Igule 2,tl)f~ lk; lf t~lt3 ~erwolk apl)r~.le~
lifJII n~llt wit~) tl)i lorl(3itL~cl~ ;Ixi~ 3f`3 ~3f tl~t3 ll~tuilt(?r iiiusL~It( (I i~ t lJI~? 1.
A~; t~t~ ;I(`t~JI~t~)I` (llLl~)r~ t?s tl)f3 cxp~ ed C(~llriltjoll t?f 1- ItI~lr~ 4~ f? f~(lr si~
Int:Sllt'S t?~3t~rl Up riIlL~ .?iL)r()llCll il I ect~ t31Ir Siltl~3t~. l )LI31?r ~-?I~ J(Il "ll Sllilpl?'i f ()I
the meslIl)s mil~ IISI'd SUCIl a"~ the :;ix-sided l?t-twolk 2ba of 1- iqurt? ~. Io e Ir h C<lSt~ tllB li(lkS Ill)~)ri)tlC~ i9r~mt?I~t Witll tllt? Inll(~itll~iiIltll i?XiS ill tlle t~xti?rlfit~l COIlCIitir)l~ d t.llf' f(l!lr Sldf`d mr?SIleS llr ~?f~ly90rlS Operl Ul.? .lS the eoclf)cillre !~X-r? i l O f ~ y ~
3( X~
SilICe tlIe entire SUI`fclCe arS~I l)f thc a(`tUat;-l` iS
empk)~ed ir-l a ful~ctior~ a~090US to cl pi3tl)1~ ilI a fluid cyiirlder, the resultarlt axial pullir19 Forc~? is ~r-~ver.lI tirnes lal`yel` thal- thE~ tntil, folce exerted b~ the prcs3urized fluid clCtill9 l)U a piStOrl inside a fluid cylinder of the S.lme diamet~r as the actliatol.
1ll the Ibf~e embodirncllt therc is a telld~l1c~ for th~
etwork to colltr lct aXb~ ' f Ister th IO thc erlclosure, resultillg ir- bucklirlg l)F
the snclosure rlear its two euds as p~essurized fluid is intrL)duced. for this 10 reasorl, the netwurk has the loose pre-inst1llatioll stai~e showrl ill 1 igure 1.
Providir1(J the iuitial stretcr1 to the enclosure upoo installatiurl, .lS illustrated ill Figure 2, prevellts tllis buckiirlg.
The theory of opr~ratiorl of the actuator 1 Ig explallled wlth ri~ferHIlc~ to Figur~s 5 to 8. The ll~twork Is r~presi~llted by a 1~ ? 4~ sf lerlgth L irl Flgure 5. At ollr el~ the l~lle is attach~d to 8 fixed moullt 42.
At the opposlte r-~lld, the Illle is attaohed to a load 44 slldably restll~g o surfacH 46.
11l figure 5, a small force FL has be~n applied perpendicular to the lir~r 40. The smalt forc~ FL produces a tt?oslon forc~
FT which is rnally tlmes larger thal~ the force FL for a small a~lgle a. At th~
same tlm~, the lo~d is mo~d a dlstallc~q D. Thc r~lat~ooships ar~? defloed by the following ~quations:
¦fT1¦ = ¦FT2¦-)FLI2 1 ¦FT¦ = ,FT1¦ +¦FT2¦ =¦FL¦
9i~
alld 1:) = L - L co~ a f igur(- 6 shows all elastom~rlc tube or ellclo~ure 3 of 35 length L. Tht~ tubr-~ is seal(~d at both ellds, but has a port 5 for admlttll1g J'~ ?si6 prr?ssuri~r?d fluid. Thr tube is surrourlded by eight i~oll-stretchs~blr?, flrtxiblr?
te~lsiol~ liuks 7, ol~ly thrr?f? of whicn carl be ss?r?ll from the ~llustrated sidrt. At their first ellds ~, the lillks are collllr3ctr3d to mour~t 42. At eheir st?r oud euds 11, t~lt? Iir~ks are r~ol~ ?ct~?d to load 44 slidably rt?stillg oll a surfacr? 46.
Whell prt3ssurizt?d fluld IS ~rltroduct3d through port 51 a pulling force F jB Cl eated due to radlal expar~siou o~ly of the ellclosure surrour~ded by the links. Refr?rrirlg to Flgure 7, the loed 44 has tra~rtlled Sldistallcr3 D1 due to the rs~dial expallsioll. Dlsts~llce D1 is gre~ter thao thr-10 dlstallce D ùf Figure 5. Thls Is becs~use the links3 are I~OW deforms.3d il~tO the arc ahaprt of Flgure 7 rather thal~ the stharp brtud of Flgure 5.
F = f PdS
5 8il~ a where P = prt?srturr3 in8ide t3l~r.~10surt S = surfacr? ares of erlclosurt?
tt = aoglr~3 bHtweell ct-l~trr~
axis 3H s~lld tarlglqllt 41 to 8 pOlllt 011 ellclo5urtt sur f ace If thr-3 links slre iuterculll~ected It regulslr iutr?r~ill^. t form sl ontwurk 1 S, sls seel~ in f igure 8, ilnd the er-closurt3 is irlflslted, sl two-25 fold .ll~plic~ttioo of the cstse of Figure 5 uccurs. r~irstly, tlle ,~ressuri~ed fiuldinsidr? the el~closure ~rovides Sl fùrce f~lOn9 the tube's Ineridiilos Sl9 Sl?ell io Figure 7. Secolldly, tellsiurl forces Tl- rtlor~9 equ~ltors of the tube product?pullil~y forces Ps- sllorlg the links uf the nr3twurk. At the ss~me tirne i~ greiltel cootrrlctiorl uf the slctuSItur uccurs~ Firstly, thr3 ellclosures Inericliilrri belld 30 iotO iul s~rc wllicb cilus~3s iictuiltor colltr ICtiOI~ rls slluwrl io Fi9Ul'e 7. Sec~ di~
due tu the reguls~r iutercollrll3ctiQrls of the l~etwork lioks, Ineridi.lo leoytlls der`reslae ila tlle r3rlcl~1surr? t3xp<lrlds r-ldi~ y, ful t~le~ lcrr3ilsirlr~ t~le dr3~ 3r3 r3f cootr Ictiorl D2 S13 'illOWrl ill Figure 8.
` 9~i, An uxlally colltrartable actuatQr accordlug to the illventiol~ of fers slgruficaot adval~tages ovt?r hydraulic or pnf-umatlc cylindr rs. Thr-~ actuator i~ ea:i;c?r to manufactur~ aud could br3 cousiderablyless expf?lls~ve thao a cylirlder. No sealirlg or leakacJe problema are llkel~ to 5 occur becausf no slidillg seals are required as In the case of cyllndr rs. Thu~
it would be very attractive for installatloll where fluid leakage Is of grr at concern. The actuator is unf3~fr~cted by 3ide forces ullllke fluld cyllllders which c~nrlot tolerate sldf forccs. At the same tlme, the actu0tor cao be ir~stalled more tlghtly thau hydraul~c cyllndt?rs, ullowlllg more sophlstlcatPd 10 robotlc srms ar~d hands to be dr?slgl~f d.
Flgures 9 to 12 Illustrate an alternat~ve actustor 1.1 which is gr?llerally slrnllur to actuator 1. Correspondlrlg parts are ournbr?rr-?d the same w~th the addltional deslgl~r~tt~ol~ ".1".
Actuutor 1.1 has all ftoclosurr~t 2.1 whlch Is ~pu~dle-ahapHd Irl the pre~ stallatior~ state of Figure 12. Thls utlows ~vel~ wall thlcklles~ after oxpanslou of the el~clorurt~.
Actuator 1.1 alrio has a nf?twork 28.1 of llon-stretchuble, flr-?xibls tellsloo links 30.1 which are ombedded In a layer 50 of fl~x~blP
material extelldlng about tho èrlclosure. The laycr may bf3 of a ~ul~able flexible plastic, for oxsrnple. The layèr of material 19 loose aod bulges outwardly at n~eshf s 52 lo thf? prc-l(lstallatiorl statrt. Thls perrnlt~? the layer 25 S0 to readlly r~tretch to the ullcos)tructftd ~tate evlqll though ~hn rnatt~ru~l erJdll't b~t elu~tolnf?rlr. Thls also pro~ Idt~s u Inllamul rt ~llttu~lcrt by tht- IL~ r 50 U(~UI119t tr~ sYr?r9rt rtxpr~oslorl to tht? axl~lly colltr~ct.r)cl 8t~tFl. At t~lld 3t,. 1 wlres cornprl~ g the nr-?twork arc placed aud borlded Ir~slde ~emlclrculur chullllel~? 35.1 e~telldlllg alollg a cyllrldt r 20.1. ~he chal~ll01s ure arrallged ~0 clrcum'erelltlully about thè cylinder. Thf! cyllllder flts over a olpple 18. !
alld IS bondtd to It. Wlre 37.1 19 woulld about cyllodt3r 20.l alld bollded to retalo wirt3s of thr~ nr3twork on tho cyllllder. 11l a slrnllar mal~ller, e ld 34.1 of the l~vtwork ~8.1 18 collnt?cted to c~llndttr 6.1 flttr?d over stud 4.1.
Actuator 1.1 also has a perforated frlctlon reduc~l-g luyer 54 in the naturt of a thln rr silir nt sheet-llkr- tube betwl3rtll the layer 50 and the enclosure 2.1. I ayr?r 54 reduces reslstcirlce to expansioll cau~ed by frlctlon betwer-3ll ~he nt-twork 28.1 and the enclosure 2.1 in colljuCtlOIl wlth5 layer 50. The perforatlolls 80 elimillate the vacuum that may be creclted betweell layers. A sultclble~ lubricarlt 3uch as all oil, grerlse or petroleum jelly is applled be~weell layer 54 url(i the erlclosure 2.1 to furthl3r redure frlct~orl. The lubrlc~llt muy ul~o be appllrtd betw~tt~ll layf3r6 50 und 54. Layftr 54 has a first e~ld 5~ alld aecoud end 59. At first end 58 It 19 fltted over and10 bonded to a flrst erld 3.1 of rtlastomrtric enclo$ure 2.1. Slmllarly,at 9ecDrld end 59 it i5 fittr d over and bonded to secolld end 16.1 of the elastomerlc enclo~iure.
Actu~tor 1.1 may hUVr3 a longrtr expectrtd Il~H thun 15 actuator 1 due to thr~ rt1duc~3d frlct~oll and rollseguent reducHd we~r on thu .snclorlure.
F~gures 14 - 17 ahow arl actuator 1.2 accordlng to a further embodimerlt of the inventiorl. This embodiment f3mploys a combined 2û encloaurrt and network 60. The walls 62 are of arl elsstomerlc materlal, suchas rubber and sf3rvr3 as the enclosure. A network 63 of non-str~tchuble, flexible links 64, such as braided wire, are embedded in walla 62. A aecoild n0twork 66 of similar or llghter wire, for example, extellds across flach of the meshes 68 of the lletwork 63. This second nHtwork stops undue outward 25 bulgulg of ellclosure 62 botweell the wires oF IlHtwork 63.
The actuator 1.2 i8 similar to previous embodimellts, haVirl9 8 port 70 for conllecti~lg a hosf3 for supplylng a pre3surizctd fluld.
Riogs 74 and 76 provide conntctiol~ mealls at opposite ends of the actuator.
30 Wirr3s or l~nks 64 extend about the rings for udded strength as may he Ref'll !n Figure 17. Rings 74 und 76 and links 64 are encapsuluted In suitable rlgld plastic bodies 75 alld 77 at each end of the actus~or.
~'~'2~
-- ~o Although ~u ~tlastomel IC matttr~al ~s pretr~rred for thl nllclosure, other sheet-llke, flexlble, noll-perme?able mater~als of plastlc, for examplrt, carl be used. Refr-?rrlllg to Flgure 9, the elltire actuator ma~
comprise the? network 28.1 ernbedded IU the noll-elastornerlc layer 50 wh~ch 5 af?rvr?s as thr? er~closurrt. The col~uectlr~g meal~s cQuld bt? of elthrtr the forrn shown ~1l Figure 9 or thr form show~l IU Flgure 14. The maLel u~l ls ovr?ra~zr?d al~d telld~ to bulge outwsr(lly betwet?ll the hilkri of the ur?twork.
Thla accommodate?s the llect?ss3ary expallsloi~ ar~d dlstortlorl of the ~?llcloaurt without tht? Ilr?r?d of r~lastomr?l8c qualities.
The invention relates to an axially contractable actuator particularly suited for robotics applications.
Robotics technology is f re~uently presented with the problem of mimicking the function of human hands and arms. Mechanical analogies to hands and arms clearly must include some replacement for the many human muscles used to f lex and move the human f ingers, hands and arms. When fluid power, either hydraulic or pneumatic, is used in robotics, a f luid cylinder appears to be a likely substitute for human muscles. However, high pressure f luid requirements due to limited fluid cylinder size and space and positicr.ing problems complicate the use of fluid cylinders or make their use impossible for some applications such as in self-propelling walking robots.
Fluid c~linders are also not entirely suitable as actuators in the food and drug industries. Restrainers must be used to contain dripping caused by leaking seals and misaligned cylinder rods.
SUMMARY OF THE INVENTION
According to the invention, an actuator has first connection means and second connection means at opposite first and second ends of the actuator respectively and is contractable along an axis extending between the connection means. The actuator comprises rneans actuated by the actuator being connectable to the connection rneans. The actuator comprises at least one hollow, flexible enclosure having an opening for adrnitting a pressurized fluid. A constraining rneans extends about the at least one enclosure for converting expansion of the actuator transversely to the axis into contraction along the axis when pressurized fluid is admitted into the at G ~P
~ -la-least one enclosure. The constraining means comprises a plurality of non-stretchable, flexible tension links intersecting to form a tubular network with meshes having four or more sides. The links are connected together at intersections of the network and are arranged so the links approach alignment with the axis when the enclosure is extended and so the meshes open up when pressurized fluid is admitted to thc? enclosure.
According to another aspect of the invention, a fluid operated actuator has expansible enclosure means having a longitudinal axis, and an axially elongated state and an axially contracted state. This fluid operated actuator also includes means for admitting pressurized fluid into the enclosure means for shifting the enclosure means between the states. The fluid operated actuator further includes constraining means disposed about the enclosure means and comprises a plurality of tension links connected together at a plurality of nodes which provides a network having a plurality of open mesh areas. Each of the mesh areas has at least four sides provided by the associated tension links and the tension links of each mesh area are substantially aligned generally in parallel with the axis when in the elongated state. The tensio links of each mesh area are disposed at a substantial angle to each other when in the contracted state and the enclosure means bulges outwardly through the mesh areas when in the contracted state.
A further aspect of the invention provides a fluid operated actuator assembly comprising an expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state. Tt-e assembly includes means for admitting pressurized ~ id into the enclos~lre means for shifting the enclosure means between the states. The assermbly ~urther incl~c~es constraining means disposed about the enclosure mealls and comprises a plurllity of tension links connected tog~ther ~l ~'2~ 9~
-lb-at a plurality of nodes, providing a networ~ having a plurality of open mesh areas. Each of the mesh areas has at least four sides defined by the associated tension links. The tension links of each mesh area are in general alignment when in the elongated state and the tension links of each mesh area are disposed at a substantial angle to each other when in the contracted state so that the open area of the mesh areas is larger in the contracted state than in the elongated state. The enclosure means bulges outwardly through the mesh areas when in the contracted state.
A still further aspect of the invention provides a fluid operated actuator comprising an expansible enclosure means having a longitudinal axis and an axially elongated state and an axially contracted state and includes means for admitting pressurized fluid into the enclosure means for shifting the enclosure means between the states. This actuator further comprises constraining means disposed about the enclosure means and comprising a plurality of tension links connected together at a plurality of nodes to provide a plurality of open mesh areas. Each of the mesh areas have at least four sides, the sides of each mesh area being substantially aligned in parallel with the axis of said enclosure means when in the elongated state. The sides of each mesh area are disposed at a substantial angle to each other when in the contracted state. The enclosure means may be non-elastomeric a,nd bulge outwardly through the mesh areas.
BRIEF DESCRIPTIOM OF THE DRAWINGS
Figure l is a side view of an actuator, according to an embodiment of the invention, in a pre-installation state;
Figure 2 is a side view of the actuator of Fiyure l in an axially uncontracted state after installation on a hinged arm;
g6 Figure 3 is a fragmentary view of an alternative embodiment having a network with six-sided meshes;
Figure 4 is a side view of the actuator of Figures 1 ancl 2 in an axially contracted position aft:er installation;
Figure 5 is a diagrammatic side view illustrating in sirnplified form the function of the network of the actuator of Figures 1 - 4;
Figure 6 are diagrammatic perspective views to 8 illustrating in simplified form the function of the actuator of Figures 1 - 9;
Figure 9 is a perspective view, partly broken away, of an ~G
b947/198 s~
actuator according to anothf?r r?mbooiment of the IIIV~ tiOII;
f lgur(~ 10 l9 ~ll r?xplodf?d pf?rl3pf~c~vl? ~ w of tht? t~tu~tor of Flgure 9;
Flgure-~ 11 is a pl~r~p~r:tivr? V~l?W of tht? fr~ction r~duclng layl?r of the actuator r f F~gurl~9 9 all(l 1(I;
figur~? 12 i~ a pf?rspf~ctivr? YleW of tht~ ela~tolnt?ric t?nclo8ure of thr? actuator of FigurH~ 9 to 11;
Fi9Ur~? 13 i9 a SHCtlO(I~I ViHW alollg linf? 13-13 of Flgurt? 11;
15 Flgure 14 i3 a sldB vicw of ~l~ actuator accordlllg to a further embodimclIt of th~? inVt?lltlOn in all axially urlcontracted 9tatt?;
FigurH 15 i9 ~ Sidt? view of tht? ~ctuator of E19Urt? 13 Ill a~ ally co~ltràcted stat~?;
f l9urt? 16 is a 8t?Ctioll~l ViHW alollg llrlt? 16-16 o f F l9urf? 15; ~lld Fl9urH 17 ls a 9Hctional vlr?w alorlg lillt? 17-17 of ~ Igure 14.
C)ESCRIPTION OF THE PRE~ ERRED EMBODIMENTS
Fl9urr? I illu8trat~s an actuator I accordlng to ao ~?mbodimsnt of thr? illVCIItiOII. Tht? actuator has a hollow t?nclosurt? 2, in thls 30 C~i9B of an etastorlle?ric material. In othsr embodirnellts a plurallt~ of cllclosures could bB us~?d togf?ther ill p~rallF?I. The ~?rlclosurr? may br? madt? of rubb~?r, syrlthr?tlrc rubbBr or a suitable t?laatomBric plastic matt?rlal. Thf?
r?nclo8urr? i~ ClOSf?d at a flrSt f?lld 3 Wht?rr? lt l'S bolldt-d abollt a thrt-ad~l st-ld or bolt 4. Tht~ ~3tud 4 provld~?s conllectloll me ll~8 for conllf~ctlll9 th~
s~
actuator to a mounting bracket 8 as ser n in Figur~ 2. The stud 4 IS
conrlected to thH bracket by 8 pln 10. The mounting bracket i9 conllected tD
an articulated arm 39 by a bolt and nut comblnatiorl 14.
Ihe ~nclo~ur~ has a ~ecolld end 16 whlch 1~ opell in th~t it 18 bonded about 8n Operl ended nipple IB. The nlppl~ h~ a thr~3adf!d outer erld 22 adapted to enlgage a fitting 24 of a hose 26 a~ shown lo F~gure 4. In this manrlr~r prssr~uri~0d fluid, such as hydrHulic fluid or pressurized air, can b~ admitted into the open snd of the enclo3ure. The nipple is conllect0d to ~
10 bracket 23 by a nut 25 and thereby comprises a secolld conrlection means of the actuator. Brucket 23 is mounted on th0 arm 39 by a nut and bolt combination 27. The bracket and arm servH as an exHmple only of msans actuated by the actuator.
The actuator has a network 28 of no~ trr~tchable, flexiblH tension link~ 30 extel)d~ng about the enclo~ure. The links may be, for example, flexibl~l braided w~rH covered with plastic. A plurallty of ~uch wires are connected together at node~ 32 to form the es~entially tubular nHtwork. Alternatively the llnks may be of other materialA s-Jch as ~ylon 20 twine. The network has u first end ~4. Similarly, the network has a secolld erld 36. At Hnd 36 the wires comprising the network pas~ through ~ plurallty of apertures 35 extelnding through a ring 20 and extendirlg circumfererltially about the ring. The ring fits over nipple 18 snd butts ag~dinst end 16 of th~
enclosure. Knots ~7 s~re formed on the ends of ~he wires to retairl the ellds of the wires on the ring. In a similar manller, end 34 of the network 28 Is colmeoted to ring 6 fitted over stud 4.
In referrillg to the actuator, axi~l dimerlsiorls and directions extend alorlg longitudirlal axis 38 of F~gurH 1 extendirlg betwE~e 30 the erlds of the erlclosure. Transverse dimerlsiorls and directions are perperldicular to thbs axis.
Figure I illu~tratss the actuator in its prH-installation or off-the-shelf collditloo. 1'ht! ellclosure 2 IS uustretched a~d the l~etwork 28 fits 1008ely r?boUt thf` (-`I~ OSUrf' IrI .I bag-llke ,na~ er. As may be oL?sr rved, tht~rl1 I? C0119lderi;~bl(1 9paCI` betwt~ell the llntwork aoc1 the f~uclos-lrt exct l)t at the ellds 54 alld -S6. It mr,y ulso br~ ot)served from F~lgurfls I alld 4 th~ the rletwork has rneshes whlt h ar(? Iarger ul-?<?r the cellter of the lletwork to flt the shapf? ofr th~- r xpc,oded f~rlclosure. Thr? mitshes are progresslvt?l~ smaller towards the two nuds of the ellclosur(:.
Flgure 2 IllusLriites the a3ctuator Irl call extr odt~(l, Inlt.l.?l collditlol~. Io this case, the el~closure hr~is bet-~l axlrilly strf tchr-d ul~tll the lletwork fits closely abouL the 0rlclosure~ Thls e3 the axlally ullcolltracted statf- oF the aettiator after lostallatiorl orl the arm 35' wlth a hl~lged or artlculated jolrlt 41. The Inltial tells~orl rt3quired ~o mail~ttilo th~s ullcolltracted at~ite is provlded by ,--, we~ght 43 conllf?cted to a bolt 45 oi~ thr-el~d of thf? arm.
lu order to corltrrict the uctu~itor e.ixliilly~ pressurl~ d3 fluid Is adrnitted illto the erlclosure by hose 26 as Illustrated ~u Flc~urf 4.
Thf? pressurizHd fluid radmitted irIto the r~r.closurt-3 Cf~U9tlS r~idec?l eXpriII9I011 ~?S
showll ~r~ Figurt? 4 where tht~ r llclosurft bulges most prorn~nelltly ~?t the m~d-2i9i poillt betw0ell its two el~ds. The lletwork acts as eollstrr~ g mearls wh~ch Is, at the sam0 time, rad~ally expsl~r'iable, but eixlally cootractablP. Thc wlrt-s or otht?r tt?llsiOIl lirlks cornprislllg thts? Ilt?twork i~rt? r sstllltl~311y Uoll-strt-~cihahle. Coosequel~tly thc radisl expailsloll of the rle~twork, rausr-~t-. hy the radir~l exp~illsloll of the ellclosuri?, must be taccompanlf3d t-~ ax!ril cootrt,ctioll of thi? a-ictuator r~-is may i.?~? observr?d by comparll)g f Igures 2 ao 4. Irl ~I)e extelldcd cooditioll o~ 1 Igule 2,tl)f~ lk; lf t~lt3 ~erwolk apl)r~.le~
lifJII n~llt wit~) tl)i lorl(3itL~cl~ ;Ixi~ 3f`3 ~3f tl~t3 ll~tuilt(?r iiiusL~It( (I i~ t lJI~? 1.
A~; t~t~ ;I(`t~JI~t~)I` (llLl~)r~ t?s tl)f3 cxp~ ed C(~llriltjoll t?f 1- ItI~lr~ 4~ f? f~(lr si~
Int:Sllt'S t?~3t~rl Up riIlL~ .?iL)r()llCll il I ect~ t31Ir Siltl~3t~. l )LI31?r ~-?I~ J(Il "ll Sllilpl?'i f ()I
the meslIl)s mil~ IISI'd SUCIl a"~ the :;ix-sided l?t-twolk 2ba of 1- iqurt? ~. Io e Ir h C<lSt~ tllB li(lkS Ill)~)ri)tlC~ i9r~mt?I~t Witll tllt? Inll(~itll~iiIltll i?XiS ill tlle t~xti?rlfit~l COIlCIitir)l~ d t.llf' f(l!lr Sldf`d mr?SIleS llr ~?f~ly90rlS Operl Ul.? .lS the eoclf)cillre !~X-r? i l O f ~ y ~
3( X~
SilICe tlIe entire SUI`fclCe arS~I l)f thc a(`tUat;-l` iS
empk)~ed ir-l a ful~ctior~ a~090US to cl pi3tl)1~ ilI a fluid cyiirlder, the resultarlt axial pullir19 Forc~? is ~r-~ver.lI tirnes lal`yel` thal- thE~ tntil, folce exerted b~ the prcs3urized fluid clCtill9 l)U a piStOrl inside a fluid cylinder of the S.lme diamet~r as the actliatol.
1ll the Ibf~e embodirncllt therc is a telld~l1c~ for th~
etwork to colltr lct aXb~ ' f Ister th IO thc erlclosure, resultillg ir- bucklirlg l)F
the snclosure rlear its two euds as p~essurized fluid is intrL)duced. for this 10 reasorl, the netwurk has the loose pre-inst1llatioll stai~e showrl ill 1 igure 1.
Providir1(J the iuitial stretcr1 to the enclosure upoo installatiurl, .lS illustrated ill Figure 2, prevellts tllis buckiirlg.
The theory of opr~ratiorl of the actuator 1 Ig explallled wlth ri~ferHIlc~ to Figur~s 5 to 8. The ll~twork Is r~presi~llted by a 1~ ? 4~ sf lerlgth L irl Flgure 5. At ollr el~ the l~lle is attach~d to 8 fixed moullt 42.
At the opposlte r-~lld, the Illle is attaohed to a load 44 slldably restll~g o surfacH 46.
11l figure 5, a small force FL has be~n applied perpendicular to the lir~r 40. The smalt forc~ FL produces a tt?oslon forc~
FT which is rnally tlmes larger thal~ the force FL for a small a~lgle a. At th~
same tlm~, the lo~d is mo~d a dlstallc~q D. Thc r~lat~ooships ar~? defloed by the following ~quations:
¦fT1¦ = ¦FT2¦-)FLI2 1 ¦FT¦ = ,FT1¦ +¦FT2¦ =¦FL¦
9i~
alld 1:) = L - L co~ a f igur(- 6 shows all elastom~rlc tube or ellclo~ure 3 of 35 length L. Tht~ tubr-~ is seal(~d at both ellds, but has a port 5 for admlttll1g J'~ ?si6 prr?ssuri~r?d fluid. Thr tube is surrourlded by eight i~oll-stretchs~blr?, flrtxiblr?
te~lsiol~ liuks 7, ol~ly thrr?f? of whicn carl be ss?r?ll from the ~llustrated sidrt. At their first ellds ~, the lillks are collllr3ctr3d to mour~t 42. At eheir st?r oud euds 11, t~lt? Iir~ks are r~ol~ ?ct~?d to load 44 slidably rt?stillg oll a surfacr? 46.
Whell prt3ssurizt?d fluld IS ~rltroduct3d through port 51 a pulling force F jB Cl eated due to radlal expar~siou o~ly of the ellclosure surrour~ded by the links. Refr?rrirlg to Flgure 7, the loed 44 has tra~rtlled Sldistallcr3 D1 due to the rs~dial expallsioll. Dlsts~llce D1 is gre~ter thao thr-10 dlstallce D ùf Figure 5. Thls Is becs~use the links3 are I~OW deforms.3d il~tO the arc ahaprt of Flgure 7 rather thal~ the stharp brtud of Flgure 5.
F = f PdS
5 8il~ a where P = prt?srturr3 in8ide t3l~r.~10surt S = surfacr? ares of erlclosurt?
tt = aoglr~3 bHtweell ct-l~trr~
axis 3H s~lld tarlglqllt 41 to 8 pOlllt 011 ellclo5urtt sur f ace If thr-3 links slre iuterculll~ected It regulslr iutr?r~ill^. t form sl ontwurk 1 S, sls seel~ in f igure 8, ilnd the er-closurt3 is irlflslted, sl two-25 fold .ll~plic~ttioo of the cstse of Figure 5 uccurs. r~irstly, tlle ,~ressuri~ed fiuldinsidr? the el~closure ~rovides Sl fùrce f~lOn9 the tube's Ineridiilos Sl9 Sl?ell io Figure 7. Secolldly, tellsiurl forces Tl- rtlor~9 equ~ltors of the tube product?pullil~y forces Ps- sllorlg the links uf the nr3twurk. At the ss~me tirne i~ greiltel cootrrlctiorl uf the slctuSItur uccurs~ Firstly, thr3 ellclosures Inericliilrri belld 30 iotO iul s~rc wllicb cilus~3s iictuiltor colltr ICtiOI~ rls slluwrl io Fi9Ul'e 7. Sec~ di~
due tu the reguls~r iutercollrll3ctiQrls of the l~etwork lioks, Ineridi.lo leoytlls der`reslae ila tlle r3rlcl~1surr? t3xp<lrlds r-ldi~ y, ful t~le~ lcrr3ilsirlr~ t~le dr3~ 3r3 r3f cootr Ictiorl D2 S13 'illOWrl ill Figure 8.
` 9~i, An uxlally colltrartable actuatQr accordlug to the illventiol~ of fers slgruficaot adval~tages ovt?r hydraulic or pnf-umatlc cylindr rs. Thr-~ actuator i~ ea:i;c?r to manufactur~ aud could br3 cousiderablyless expf?lls~ve thao a cylirlder. No sealirlg or leakacJe problema are llkel~ to 5 occur becausf no slidillg seals are required as In the case of cyllndr rs. Thu~
it would be very attractive for installatloll where fluid leakage Is of grr at concern. The actuator is unf3~fr~cted by 3ide forces ullllke fluld cyllllders which c~nrlot tolerate sldf forccs. At the same tlme, the actu0tor cao be ir~stalled more tlghtly thau hydraul~c cyllndt?rs, ullowlllg more sophlstlcatPd 10 robotlc srms ar~d hands to be dr?slgl~f d.
Flgures 9 to 12 Illustrate an alternat~ve actustor 1.1 which is gr?llerally slrnllur to actuator 1. Correspondlrlg parts are ournbr?rr-?d the same w~th the addltional deslgl~r~tt~ol~ ".1".
Actuutor 1.1 has all ftoclosurr~t 2.1 whlch Is ~pu~dle-ahapHd Irl the pre~ stallatior~ state of Figure 12. Thls utlows ~vel~ wall thlcklles~ after oxpanslou of the el~clorurt~.
Actuator 1.1 alrio has a nf?twork 28.1 of llon-stretchuble, flr-?xibls tellsloo links 30.1 which are ombedded In a layer 50 of fl~x~blP
material extelldlng about tho èrlclosure. The laycr may bf3 of a ~ul~able flexible plastic, for oxsrnple. The layèr of material 19 loose aod bulges outwardly at n~eshf s 52 lo thf? prc-l(lstallatiorl statrt. Thls perrnlt~? the layer 25 S0 to readlly r~tretch to the ullcos)tructftd ~tate evlqll though ~hn rnatt~ru~l erJdll't b~t elu~tolnf?rlr. Thls also pro~ Idt~s u Inllamul rt ~llttu~lcrt by tht- IL~ r 50 U(~UI119t tr~ sYr?r9rt rtxpr~oslorl to tht? axl~lly colltr~ct.r)cl 8t~tFl. At t~lld 3t,. 1 wlres cornprl~ g the nr-?twork arc placed aud borlded Ir~slde ~emlclrculur chullllel~? 35.1 e~telldlllg alollg a cyllrldt r 20.1. ~he chal~ll01s ure arrallged ~0 clrcum'erelltlully about thè cylinder. Thf! cyllllder flts over a olpple 18. !
alld IS bondtd to It. Wlre 37.1 19 woulld about cyllodt3r 20.l alld bollded to retalo wirt3s of thr~ nr3twork on tho cyllllder. 11l a slrnllar mal~ller, e ld 34.1 of the l~vtwork ~8.1 18 collnt?cted to c~llndttr 6.1 flttr?d over stud 4.1.
Actuator 1.1 also has a perforated frlctlon reduc~l-g luyer 54 in the naturt of a thln rr silir nt sheet-llkr- tube betwl3rtll the layer 50 and the enclosure 2.1. I ayr?r 54 reduces reslstcirlce to expansioll cau~ed by frlctlon betwer-3ll ~he nt-twork 28.1 and the enclosure 2.1 in colljuCtlOIl wlth5 layer 50. The perforatlolls 80 elimillate the vacuum that may be creclted betweell layers. A sultclble~ lubricarlt 3uch as all oil, grerlse or petroleum jelly is applled be~weell layer 54 url(i the erlclosure 2.1 to furthl3r redure frlct~orl. The lubrlc~llt muy ul~o be appllrtd betw~tt~ll layf3r6 50 und 54. Layftr 54 has a first e~ld 5~ alld aecoud end 59. At first end 58 It 19 fltted over and10 bonded to a flrst erld 3.1 of rtlastomrtric enclo$ure 2.1. Slmllarly,at 9ecDrld end 59 it i5 fittr d over and bonded to secolld end 16.1 of the elastomerlc enclo~iure.
Actu~tor 1.1 may hUVr3 a longrtr expectrtd Il~H thun 15 actuator 1 due to thr~ rt1duc~3d frlct~oll and rollseguent reducHd we~r on thu .snclorlure.
F~gures 14 - 17 ahow arl actuator 1.2 accordlng to a further embodimerlt of the inventiorl. This embodiment f3mploys a combined 2û encloaurrt and network 60. The walls 62 are of arl elsstomerlc materlal, suchas rubber and sf3rvr3 as the enclosure. A network 63 of non-str~tchuble, flexible links 64, such as braided wire, are embedded in walla 62. A aecoild n0twork 66 of similar or llghter wire, for example, extellds across flach of the meshes 68 of the lletwork 63. This second nHtwork stops undue outward 25 bulgulg of ellclosure 62 botweell the wires oF IlHtwork 63.
The actuator 1.2 i8 similar to previous embodimellts, haVirl9 8 port 70 for conllecti~lg a hosf3 for supplylng a pre3surizctd fluld.
Riogs 74 and 76 provide conntctiol~ mealls at opposite ends of the actuator.
30 Wirr3s or l~nks 64 extend about the rings for udded strength as may he Ref'll !n Figure 17. Rings 74 und 76 and links 64 are encapsuluted In suitable rlgld plastic bodies 75 alld 77 at each end of the actus~or.
~'~'2~
-- ~o Although ~u ~tlastomel IC matttr~al ~s pretr~rred for thl nllclosure, other sheet-llke, flexlble, noll-perme?able mater~als of plastlc, for examplrt, carl be used. Refr-?rrlllg to Flgure 9, the elltire actuator ma~
comprise the? network 28.1 ernbedded IU the noll-elastornerlc layer 50 wh~ch 5 af?rvr?s as thr? er~closurrt. The col~uectlr~g meal~s cQuld bt? of elthrtr the forrn shown ~1l Figure 9 or thr form show~l IU Flgure 14. The maLel u~l ls ovr?ra~zr?d al~d telld~ to bulge outwsr(lly betwet?ll the hilkri of the ur?twork.
Thla accommodate?s the llect?ss3ary expallsloi~ ar~d dlstortlorl of the ~?llcloaurt without tht? Ilr?r?d of r~lastomr?l8c qualities.
Claims (36)
1. An actuator (1) having first connection means (4) and second connection means (18) at opposite first and second ends (3,16) of the actuator respectively and being contractable along an axis (38) extending between the connection means, means (23,24) actuated by the actuator being connectable to the connection means, the actuator comprising:
(a) at least one hollow, flexible enclosure (2) having an opening (18) for admitting pressurized fluid; and (b) a constraining means (28) extending about the at least one enclosure for converting expansion of the actuator transversely to the axis into contraction along the axis when pressurized fluid is admitted into the at least one enclosure, the constraining means comprising a plurality of non-stretchable, flexible tension links (30) intersecting to form a tubular network (28) with meshes having four or more sides, the links being connected together at intersections (32) of the network and being arranged so the links approach alignment with the axis when the enclosure is extended and so the meshes open up when pressurized fluid is admitted to the enclosure.
(a) at least one hollow, flexible enclosure (2) having an opening (18) for admitting pressurized fluid; and (b) a constraining means (28) extending about the at least one enclosure for converting expansion of the actuator transversely to the axis into contraction along the axis when pressurized fluid is admitted into the at least one enclosure, the constraining means comprising a plurality of non-stretchable, flexible tension links (30) intersecting to form a tubular network (28) with meshes having four or more sides, the links being connected together at intersections (32) of the network and being arranged so the links approach alignment with the axis when the enclosure is extended and so the meshes open up when pressurized fluid is admitted to the enclosure.
2. An actuator as claimed in Claim 1, wherein the constraining means is simultaneously contractable along the axis and expandable transversely to the axis.
3. An actuator as claimed in Claim 2, wherein the tension links are connected together at intervals so the network (28a) comprises meshes with six sides when open.
4. An actuator as claimed in Claim 2, where the tension links are connected together at intervals so the network (28) comprises means with four sides when open.
5. An actuator as claimed in Claim 1, wherein the network has meshes which are larger near the center of the network and are progressively smaller towards the ends of the enclosure.
6. An actuator as claimed in Claim 1, wherein the enclosure is elongated in a dimension along the axis.
7. An actuator as claimed in Claim 1, wherein the network is non-integral with the enclosure, permitting relative movement between the enclosure and the network.
8. An actuator as claimed in Claim 1 or Claim 7 wherein the enclosure is of an elastomeric material.
9. An actuator as claimed in Claim 1, wherein the enclosure is spindle-shaped when the actuator is uncontracted.
10. An actuator as claimed in Claim 1, wherein the network is operatively connected to the enclosure at the ends of the actuator, and fits closely about the enclosure in an axially uncontracted state.
11. An actuator as claimed in Claim 10, wherein the actuator has a pre-installation state where the network fits loosely about the enclosure, the enclosure being axially stretchable to the uncontracted state.
12. An actuator as claimed in Claim 1, wherein the network is embedded in a layer (50) of a resilient material forming a tube extending about the enclosure.
13. An actuator as claimed in Claim 12, further comprising a friction reducing layer (50) between the network and the enclosure, the friction reducing layer comprising a tube formed of a resilient, sheet-like material.
14. An actuator as claimed in Claim 13, further comprising a lubricant between the friction reducing layer and the enclosure.
15. An actuator as claimed in Claim 13, further comprising a lubricant between the network and the friction reducing layer.
16. An actuator as claimed in Claim 13, wherein the friction reducing layer is perforated.
17. An actuator as claimed in Claim 1, wherein the constraining means is embedded in l he enclosure.
18. An actuator as claimed In Claim 17, further comprising additional links extending within meshes of the network for limiting bulging of the enclosure.
19. An actuator as claimed in Claim 5, wherein the network is non-integral with the enclosure and enclosure is of a sheet-like flexible non-permeable and non-elastomeric material.
20. An actuator as claimed in Claim 19, wherein the constraining means is embedded in the enclosure.
21. An actuator as claimed in Claims 18 or 19 wherein the layer of resilient material is oversized and bulges or extends outwardly in meshes between the links of the network in the uncontracted state.
22. A fluid operated actuator, comprising:
(a) expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and, (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes providing a network having a plurality of open mesh areas and each of said mesh areas having at least four sides provided by the associated tension links and the tension links of each mesh area are substantially aligned generally in parallel with said axis when in said elongated state and the tension lines of each mesh area are disposed at a substantial angle to each other when in the contracted state and said enclosure means bulging outwardly through said mesh areas when in said contracted state.
(a) expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and, (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes providing a network having a plurality of open mesh areas and each of said mesh areas having at least four sides provided by the associated tension links and the tension links of each mesh area are substantially aligned generally in parallel with said axis when in said elongated state and the tension lines of each mesh area are disposed at a substantial angle to each other when in the contracted state and said enclosure means bulging outwardly through said mesh areas when in said contracted state.
23. The actuator of Claim 22, wherein:
(a) connection means being disposed at opposite ends of said enclosure.
(a) connection means being disposed at opposite ends of said enclosure.
24. The actuator of Claim 22, wherein:
(a) said enclosure means being non-elastomeric.
(a) said enclosure means being non-elastomeric.
25. The actuator of Claim 22, wherein:
(a) said tension links being non-extensible.
(a) said tension links being non-extensible.
26. The actuator of Claim 25, wherein:
(a) said tension links including wire.
(a) said tension links including wire.
27. The actuator of Claim 22, wherein:
(a) said contracting means being embedded in said enclosure means.
(a) said contracting means being embedded in said enclosure means.
28. A fluid operated actuator assembly, comprising:
(a) expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes providing a network having a plurality of open mesh areas and each of said mesh areas having at least four sides defined by the associated tension links, the tension links of each mesh area are in general alignment when in said elongated state and the tension links of each mesh area are disposed at a substantial angle to each other when in the contracted state so that the open area of said mesh areas is larger in the contracted state than in the elongated state and said enclosure means bulging outwardly through said mesh areas when in said contracted state.
(a) expansible enclosure means having a longitudinal axis, an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes providing a network having a plurality of open mesh areas and each of said mesh areas having at least four sides defined by the associated tension links, the tension links of each mesh area are in general alignment when in said elongated state and the tension links of each mesh area are disposed at a substantial angle to each other when in the contracted state so that the open area of said mesh areas is larger in the contracted state than in the elongated state and said enclosure means bulging outwardly through said mesh areas when in said contracted state.
29. The assembly of Claim 28, wherein:
(a) said enclosure means being elastomeric.
(a) said enclosure means being elastomeric.
30. The assembly of Claim 28, wherein:
(a) said tension links being non-extensible.
(a) said tension links being non-extensible.
31. The assembly of Claim 30, wherein:
(a) said tension links including wire.
(a) said tension links including wire.
32. The assembly of Claim 28, wherein:
(a) connection means being secured to said constraining means and said enclosure means at the ends thereof permitting attachment to an item to be moved.
(a) connection means being secured to said constraining means and said enclosure means at the ends thereof permitting attachment to an item to be moved.
33. The assembly of Claim 28, wherein:
(a) said constraining means being embedded in said enclosure means.
(a) said constraining means being embedded in said enclosure means.
34. The assembly of Claim 28, wherein:
(a) said enclosure means being non-elastomeric.
(a) said enclosure means being non-elastomeric.
35. A fluid operated actuator, comprising:
(a) expansible enclosure means having a longitudinal axis and an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and, (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes to provide a plurality of open mesh areas, each of said mesh areas having at least four sides, the sides of each mesh area being substatially alinged in parallel with the axis of said enclosure means when in said elongated state and the sides of each mesh area being disposed at a substantial angle to each other when in the contracted state.
(a) expansible enclosure means having a longitudinal axis and an axially elongated state and an axially contracted state and including means for admitting pressurized fluid into said enclosure means for shifting said enclosure means between said states; and, (b) constraining means disposed about said enclosure means and comprising a plurality of tension links connected together at a plurality of nodes to provide a plurality of open mesh areas, each of said mesh areas having at least four sides, the sides of each mesh area being substatially alinged in parallel with the axis of said enclosure means when in said elongated state and the sides of each mesh area being disposed at a substantial angle to each other when in the contracted state.
36. A fluid operated actuator as claimed in Claim 35, wherein the enclosure means is non-elastomeric and bulges outwardly through said mesh areas.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55353083A | 1983-11-21 | 1983-11-21 | |
| US06/553,530 | 1983-11-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1228096A true CA1228096A (en) | 1987-10-13 |
Family
ID=24209775
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467704A Expired CA1228096A (en) | 1983-11-21 | 1984-11-13 | Axially contractable actuator |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS60132103A (en) |
| CA (1) | CA1228096A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113771021A (en) * | 2021-09-23 | 2021-12-10 | 清华大学 | Rigid-flexible coupling driver based on dielectric elastomer |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3003702B2 (en) * | 1987-11-13 | 2000-01-31 | 株式会社東芝 | Actuator |
| JP4245841B2 (en) * | 1999-11-11 | 2009-04-02 | ホフマン クロイツ | Clamp and / or brake device |
| US7299741B2 (en) | 2003-03-25 | 2007-11-27 | Hitachi Medical Corporation | Hydraulic pressure actuator and continuous manual athletic device using the same |
| WO2006080088A1 (en) * | 2005-01-31 | 2006-08-03 | Squse Inc. | Actuator, drive device, and hand device |
| WO2008140032A1 (en) * | 2007-05-11 | 2008-11-20 | Chuo University | Fluid pouring type actuator |
| US8701545B2 (en) | 2008-04-02 | 2014-04-22 | Squse Inc. | Rotation device |
| GB2467762B (en) * | 2009-02-13 | 2013-08-14 | Shadow Robot Company Ltd | Robotic musculo-skeletal jointed structures |
| JP6226359B2 (en) * | 2013-05-16 | 2017-11-08 | 国立大学法人 岡山大学 | Hydraulic actuator and bending drive device |
| JP6292580B2 (en) | 2015-02-20 | 2018-03-14 | 株式会社コガネイ | Actuator |
-
1984
- 1984-11-13 CA CA000467704A patent/CA1228096A/en not_active Expired
- 1984-11-21 JP JP24469684A patent/JPS60132103A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113771021A (en) * | 2021-09-23 | 2021-12-10 | 清华大学 | Rigid-flexible coupling driver based on dielectric elastomer |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60132103A (en) | 1985-07-15 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |