CA1069478A - Actuators - Google Patents

Actuators

Info

Publication number
CA1069478A
CA1069478A CA287,459A CA287459A CA1069478A CA 1069478 A CA1069478 A CA 1069478A CA 287459 A CA287459 A CA 287459A CA 1069478 A CA1069478 A CA 1069478A
Authority
CA
Canada
Prior art keywords
tube
end closure
flowable material
closure elements
temperature
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
Application number
CA287,459A
Other languages
French (fr)
Inventor
Anthony J. Lawrence
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tungum Hydraulics Ltd
Original Assignee
Tungum Hydraulics Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Tungum Hydraulics Ltd filed Critical Tungum Hydraulics Ltd
Priority to CA287,459A priority Critical patent/CA1069478A/en
Application granted granted Critical
Publication of CA1069478A publication Critical patent/CA1069478A/en
Expired legal-status Critical Current

Links

Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A40/00Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
    • Y02A40/10Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
    • Y02A40/25Greenhouse technology, e.g. cooling systems therefor

Landscapes

  • Infusion, Injection, And Reservoir Apparatuses (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE
A thermally sensitive actuator consists of a pressure cylinder comprising a tube, two end closure elements each secured to a respective end of the tube, a body of flowable material contained within the tube between the end closure elements, and a piston extending through a through-bore in one of the end closure elements and projecting into the body of flowable material.
During assembly, the said body of flowable material is disposed within the tube between and abutting said end closure elements, while at least one of said end closure elements is not secured to the tube, so that said body of flowable material determines the distance apart of said end closure elements. The end closure elements are secured to the tube by displacing the peripheral edges of the ends of the latter inwardly.

Description

94L~
This invention relate~ ~o actuator~ and more particularly to thermally sensltive actuator~.
The particular type o~ actuator in relation to ~hich the inventio~ ha~ been de~eloped 1~ ~or u~e in operating mechani8mB ~or ventllation purpos~9 ~or example ~or opening and clo~ng greenhou~e window3;
the actuator compri~ing a presRure cglinder containing a piston which i8 displaceable outnrardl~ of the cylln~er upon expa~ion of a ~l~vable material contained within the cylinder, sald materlal bein~ wa~ or other material, ~uch as alcohol or mercur~, havi~g a high coef~icient o~ thermal expan~ion. Such cylin~ers comprise a tube ~ -and two en~ closure elemente~ oae o~ which i~ o~ solid .:
or co~tinuous form and ~he other o~ which iæ provided ~ith a through bore to recelY~ the pi3ton rod.
In commo~ly used methods o~ pro~uction the end closure elements are a~a¢hed to the ~ube b~ brazing and : the th~rmall~ indu ed c~ange~ in the metal tructure ~h~ch rl~e from the b~azing proce~3 tend to produce area~ of reduced m~chan~cal ~treng~h ad~acent the braze.
Bulging, or e~e~ rupture, Or the tube adjaca~t the ends thereor i8 thUB liable ~o occur when the ambie~t temperature ~xcee~ the temperature at ~hich ~o rurther outward mo~ement o~ th0 plston i8 possible.
It 1~ accordi~gly a gpeci~ic ob~ect o~ the in~e~tion:to pro~ide an actuator o* the abo~e tgpe ln which the end clo~ur~ eleme~s are eecured to th~ tubs b~ a ~ethod ~hieh does no~ in~o~Ye bra~lng or other ~ratlonB invol~i~g applica~io~ of heat~ ~ mors gen~ral:o~Joot~s~the pro~l-lon of a ~ethod o~
assembll~g a~ actuator o~ the abovs type ~hich i~Yol~s :
~i~ple~ ~ml~ac ur~g ~roce~se~0 ~6~

- According to a first aspect of the invention, there is provided an actuator having a pressure cylinder comprising a tu~e two end closure elements, each of ~hich is secured within a respective end of the tube, the peripheral edge of at least one end of the tube being displaced inwardly to retain the corresponding end closure element in pos~tion, the tube containing a body o~ flowable material between the end closure elements, and one of the closure elements having a through-bore through which extends a piston which projects into the flowable material.
According to a further aspect of the present invention, there is- provided a method of assembling an actuator having a pressure cylinder comprising a tube, two end closure elements each secured to a respective end of the ~ :
tube~ a body of flo~able material contained within the tube between the end closure elements, and a piston extending through a through-bore ~n one of the end closure elements and pro-jecting into the body of flowa~le material, said method includ-ing the steps o~ securing to one end of the tube the end clo-sure element through which the piston extends 7 fully extending ~ ;
the piston, insertiny heated flowable material into the tube with the open end thereof uppermost, cooling the flowable material to a first temperature at which it hardens, inserting the other end closure element into the open upper end of the tube, securing said other end closure element to the tube, and ..
heating the body o~ f1owable material to a second higher tem-j perature whereby it expands and forces the end closure elements : .
outwards from the positions in which they were initially secured.
An embodiment o~ the invention will now be described ~ : :

by way of example with reference to the accompanying drawing ~:
which is a longitudinal cross-section through a thermally ~69~7~3 sensitive actuator.
The actuator comprises a tube 10, the ends of which are closed by respective end closure elements 11 and 12. The portion o~ the tube 10 between the 6~78 closure element~ i8 ~lled wlth a body o~ ~lowable materlal, such as wax, alcohol or m~rcury, hav~ng a high coe~icient of thermal expansion. A respective resilient "0~ r~ng 13, 14 i8 fitted in a groove in the outer periphery of each Or the end closure elemen~
and t2 to provide a seal between such end clo~ure ~lement and the inner wall o~ the tube~
A piston 15, in the ~orm o~ a rod, extend~
through a through-bore 16 in the end clo~ure element 12 and pro~ects into the ~lo~able material. The inner e~d o~ the through-bore 16 ~8 enlarged to accommodate a resilient ~eal 17 ~hich engages b~tween the end clo~ure element 12 and the piston 15 and is held in place by an inwardly directed lip 18 ~ormed on the edge o~ such enlarg~d reces~
Pre~erably, as shown~ the inner end o~ the pi6ton 15 taper~ to a point 1g ~0 that 9 should the pi~ton ~5 b~ forced to its ~ully inward posltion in ~hich it make~ contaet ~lth the ena clo~ure e~eme~t 11~ the flowable material i~ the tube can exert pre~Bure on the tapering ~urface ad~cent the point ~9 when expansion next take~ place. A pin 20 extends tran8~erBely through the piBton 15 near ~he inner end ~ :
thereo~ and eer~e~ 9 by engagement w~th the cloaure element 12~ to pre~ent complete withdrawal o~ th~ pl ston ~5 ~rom the tube 10.
I~ the flowa~1 material i8 a ~aterial ~hich ca~ be ~rozen at temperatur~ not i~co~veniently lower ..
than room temperature, a unit o~ ~lo~able m~terial may b~ formed by producing a ca~ti~g Or the aolidi~ied material ~haped to ~ thin the tu~ 10 and lncluding :-a central hole to accommodate the piston t5 when the latter :~
- .

~6~47~

i 8 inserted into the tube 10 to it 8 maximum extent .
The tube 10, unit o~ fr~ozen flowable mater~al, pi~t ~5, and end closure element~ 11 and 12 may then be assembled together with the unit o~ fl~v/able materlal ~ervin~ to mainta~n the required spacin~ between the two end closure element6 11 and 12 wh~ch are then secured in po~tion in their respective enfls o~ the tube ~00 Th~ la~er operation may conveniently be e~rected b~ pre6~ing the end edges 2~ and 22 o~ the tube inwardly 80 aB to embrace the respective end closure ele~ents ~1 ana 12.
A~ an al~ernative to ~reezin~ the flowable material, a unit thereof may be ~ormed b~ insertine the material, in liquia ~orm, into a ~kin formed ~rom ~5 rle~ble 6heet material such a8 polyethylene~ Th~
; package of ~lowable mat~rial 80 ~ormed iB then in3erted into the tube 10 an~ t~e end closure ele~ents 11 and 12 ~itted w~th the pi~ton 15 ~ithdrawn to lt~ ma~lmum extent. Then, ~ith the end cloaure elements 11 and 12 held in po~ition, the piston rod 15 ia dri~en lnto the tube 10 so as to pierce the poly~thylene or other ~heet materialO Finally the end closure elements 11 and 12 are ~ecured in their per~anent po~itionB. The presence o~ the sheet material in the tu~e 10 has no ~ffect sn ~ubs~quent operation.
A ~urther:msbhod o~ a6semblln~ the ac~uator :
sho~n i~ the dra~lng, for u~e with a nowabl~ material :
~uch a~ ~a~ ~hich hardeQs a~ th~ er end o~ the ~
temperature range ~ncounterea 1~ ~ormal U8~ . . .::
3 initlally to ~it th~ e~d closure o~eme~t 12, ~ith the ~ pisto~ 15 already ~ns~alled therei~ lnto one end o~
,, the tub~ 10 a~d di~place the edBe o~ 6uch e~d i~wardly - 5 ~

3L~69.478 to retain the end clo~ure element 12 ~n positionO
~ext~ With the piston 15 ~ully extended 80 that the pin 20 abut~ against the end clo~ure element 12 and the tube 10 held vertlcal with its open end upward~, heated flowable materlal 18 poured in to completely ~ill the tube 100 The a~sembly iB then co~led to a predetermined temperatUre~ cau~lng ~he flowable mat~rial to con~ract~ h~rden and ~orm a menl~cu~ at the open end of the tube 10. The M owable material 1B then cut ~ay to a predetermined depth ~rom the open end o~ the tube and9 w~th the a~sembly Bt~ 11 at the predetermined temperature and ~ith the piaton 15 still ~ully extended, the other end closure element 11 i~ inserted 80 that ~t re8t8 on the top o~ the t5 ~lowable material and the edge o~ the ad~aeent end of the tube 10 iB displaced inw~rdl~ to hold the end closure eleme~t 11 in po~itio~0 Next~ the a~sembly :
~s heated to a second, higher predetermined temperature~ cauR~*g the ~lowabl~ material to expand~
forcing the end clo6ure elemen~6 ~1 a~d 12 outward~
The outer edges Or the end clogure elementa 11 and ~.2 which are initially o~ very ~mall r~diu~ bite into the overlapping i~wardly di~placed enae o* the tube 10 and~ at the s~me time~ ~ecome more rounded~ The o~erall e~fect ~8 to ~Crea~6 the volum~ of ~he chamber containing the ~ able material 80 that ~hen the :~
asaem~ly i8 again ~ooled ~o a temperature at whiCh the ~low~ble material h~rden6~ the plsto~ t5 i~ :
draw~ ~nto the tube 100 3~ I~ use~ the ~d clos~re el6me~t 11 i~ ;
- coupled to a ~lr~t membe~ and the pis~on to a ~eco~d . . member~ the po~itions of ~hich m~mb~r~9 one relati~

:

~L~6~7~3 to the other g are to be ~ar~ed in dependence on ambient temperature.

:

..

.

:
, ; . : . -:

7 ~
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Claims (3)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:
1. A method of assembling an actuator having a pressure cylinder comprising a tube, two end closure elements each secured to a respective end of the tube, a body of flowable material contained within the tube between the end closure elements, and a piston extending through a through-bore in one of the end closure elements and projecting into the body of flowable material, said method including the steps of securing to one end of the tube the end closure element through which the piston extends, fully extending the piston, inserting heated flowable material into the tube with the open end thereof uppermost, cooling the flowable material to a first temperature at which it hardens, inserting the other end closure element into the open upper end of the tube, securing said other end closure element to the tube, and heating the body of flowable material to a second higher temperature whereby it expands and forces the end closure elements outwards from the positions in which they were initially secured.
2. A method according to claim 1, including the further step, after cooling the flowable material to said first temperature and before inserting the other end closure element into the open upper end of the tube, of removing flowable material to a predetermined depth from the open end of the tube.
3. A method according to claim 1, wherein the flowable material is chosen to be solid at said first temperature and liquid at the temperature to which it is heated before being inserted into the tube.
CA287,459A 1977-09-26 1977-09-26 Actuators Expired CA1069478A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA287,459A CA1069478A (en) 1977-09-26 1977-09-26 Actuators

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA287,459A CA1069478A (en) 1977-09-26 1977-09-26 Actuators

Publications (1)

Publication Number Publication Date
CA1069478A true CA1069478A (en) 1980-01-08

Family

ID=4109623

Family Applications (1)

Application Number Title Priority Date Filing Date
CA287,459A Expired CA1069478A (en) 1977-09-26 1977-09-26 Actuators

Country Status (1)

Country Link
CA (1) CA1069478A (en)

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