CA1061578A - Stored energy motor - Google Patents
Stored energy motorInfo
- Publication number
- CA1061578A CA1061578A CA282,043A CA282043A CA1061578A CA 1061578 A CA1061578 A CA 1061578A CA 282043 A CA282043 A CA 282043A CA 1061578 A CA1061578 A CA 1061578A
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- CA
- Canada
- Prior art keywords
- motor
- gas
- vessel
- liquefied gas
- passage
- 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.)
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- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
MOTORS
Abstract of the Disclosure A motor of the kind which is driven by gas evaporated from a liquefied gas has in combination therewith gas supply apparatus comprising a vessel containing the liquefied gas, a passage in communication with the motor for the flow of gas evaporating from the liquefied gas in the vessel, valve or other means operable to permit gas evaporating from the liquefied gas to flow into the motor, and, in thermal communication with the vessel or the passage (or both), a container charged with a buffer substance (which is normally a liquid which has a freezing point at normal pressure above the boiling point of the liquefied gas) which acts as a source of heat.
Abstract of the Disclosure A motor of the kind which is driven by gas evaporated from a liquefied gas has in combination therewith gas supply apparatus comprising a vessel containing the liquefied gas, a passage in communication with the motor for the flow of gas evaporating from the liquefied gas in the vessel, valve or other means operable to permit gas evaporating from the liquefied gas to flow into the motor, and, in thermal communication with the vessel or the passage (or both), a container charged with a buffer substance (which is normally a liquid which has a freezing point at normal pressure above the boiling point of the liquefied gas) which acts as a source of heat.
Description
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This invention relates to motors and to gas supply apparatus for use in association with motors.
Motors which run on liquefied gases are. known and have for instance been used to power model aircraft lusing sometimes a bottle. of pressure-liquefied carbon dioxide).
A major difficulty which arises with such motors is the progressive fall in gas pressure which occurs as gas flows ~rom the bottle or tank in order to drive ~he motor, and which limits the power of the motor to a rathPx .
low level. This fall in pressure is a consequence of the cool-ing of ~he gas as it iattemp~s to evapora~e from the liquid state in the s.upply bottle and to expand against ambient pressure during consumption by the motor. .This cooling effect becomes worse as one attempts to lncrease the speed and power of the motor and can even cause forma~ion . , , ~ , ~
of ice on the outside of the bottle~ Furthermore the cooling of thQ gas causes its density ~o increase with ~he result that gas consumption is increased undesirably.
A further disadvantage of exis~ing motors powered by . .
.vaporised gas arises because the gas taken from ~he bottlè for such e~isting motors is at or near the condition known as "saturation" with the consequence that, as soon as it is e~panded in the motor, i~
in~vltably condenses partly back into its liquid or even its solid state~ Apart fxom khe possibility o~ damage to the motor such condensation also causes a large lncrease ., . . .. ~ . . .... . . .
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in ~he sl~écil`i c volun~e oî the ~Yorking Llui~l an~ l;his requires ;hat the mc)tor shoulcl have a high exp.~llsiorl ratio in order adequately to expand tl~ ~vorkin~ fluid and so extract its avai lable ener~y, and this in turn leads to t11e need ~or an undesirably lar~e motor, or to an undesirably low charge volume (wllich reduces motor po~Yer), or to the need ~or excessively high rpm in order to secure sufficient power from the motor. One proposal ~or overcoming the problem of condensation o~ the gas in the motor is to superheat the gas be~ore it is used in the motor, that is to increase its heat at sensibly constant pressure, br to reduce its pressure at sensibly constant temperature (or any combination of these two processes).
Although the value of superheating has sometimes been recognised in existing motors, the usual technique of achieving it has been by leadillg the gas from the supply bottle through fine-bore metal tubing be~ore admission to the motor, this metal tubing usually bein~ coiled and positioned so tha* ambient air flows over the tubing during operation. (Existing motors are usually adapted to fly model planes and so have a propellor which blo~vs air over the n~etal tubing). This technique ~ives a small but si~nificant improvement in performance, though not overco~i~g the problem of ondensation, diseconomy, power loss and possible motor damage at high power settings and, being reliant on the temperature o~ the ambient air to provide the superheatinG, is not very effective in cold weather when the extent of power loss can be severe.
Moreover it does not give ~ significant expansion of the ~as as it passes to ~he motor.
According to a first asl)ect of the present invention there is provided a mvtor ~vhose reciproca~le or rotrary element(s) is (or are) a~a~ted to be driven by evaporated liquid gas, ~ -3-.
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the motor having associated therewith a vessel containing liquefied gas under pressure or being capable of being charged with lique~ied gas, a passage which af~ords communication between the ullage space of the vessel and the element(s) or which by operation of valve or other means is able to provide communica-tion between the ullage space of the vessel and chamber(s) which house(s) the element(s), and in heat conductive relationship with the vessel or the passage (or both), at least one container holding or capable of being charged with buffer substance (as hereinafter defined).
By the term "buffer substance" is meant a substance which undergoes a change in its physical, chemical crystallo-graphic or other state at a temperature between amhient temperature and the final operating temperature of the liquefied gas, the change of state then causing a release of heat, to the liquid gas or evaporated liquefied gas. This heat may be derived from its latent heat of fusion, or from its laten-t heat of vapour-isation, or from its heat of hydration, or from.an~ other effect which causes a significant release of heat at a certain falling temperature and which, advantageously, re-absorbs that heat reversibly as the temperature rises again. Substances from which the buffer substance may be selected include a very large number of alternatives (as listed for instance in the CRC "Handbook of Chemistry and Physics", 55th Edition, Pages B 63 to B-156, B-243 to B-247, C-639 to C-658, and C-680 to C-719.) ~ 4 ~
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'` h~. ' Motors making use of this buff.ering technique are referred to herein as "s~:ored ener~y motors" because their buffer substances effectively store heat energy which is released.
to the working fluid for conversion into power as the motor runs. In the case of stoxed energy mo~or~; running on CO~ at normal ambient temperatures, suitable buffers include acetic acid (MP circa 16C), formic acid (MP circa 8C), and water (MP OQC), and mixtures of these materials i~ which allow other melting points to be achieved: for instance a mixture of 99~ acetic acid and 1% water by o volume has a meltlng point near 10 C which is useful for stored energy motors ~unning in temperate climates~
The above buffers are attractive by virtue of their ~iigh latent heats of fusion, whereby a relatively small amount of buffer substance suffices (eg o~e gram o~ buffer per thxee or four grams of C02 in the case of a water buffer).
The above buf ~ers are also very inexpensive and so may b~ used, ~or example, in disposable C02 bulbs. Anoth~r desirable quality of the buffer subst~nce is a high~ermal conductivity, to facilltate heat flow from the buffer into the Co2(orother gas being used), and into the buffer from the surrounding environment. Water is particul'arly good in this respect. The function of the bu~fer substance in thexmal contact with the vessel is to prevent the liquefied gas from sustaining a serious fall in temperature and pressure as it evaporates~ The bufer achieves thls function by releasing heat to the liqueied gas as its tempera~ure attempts to fall. For example the . ' . . ' ' .
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Inl:Cfcl r~ay b~ a subst~ ce ~llich has a r~cltin, l~oill t oL
O to 10C .md ~hicl~ is there~ore in its li~lui(l st~te at norl.lal ,u,~ nt ter.lperatur~s, Thell, in the case o-F
a C02 ~otor fol e,;~mple (tllou~,h the invent~on is - equally applicable to other ~ascs), as the C02 gas is drawn OII to drive the motor tlle rer.lainin~; C02 in tlle bottle ~Yill bccohe colder l~ut, bein~ in ~ood t~lermal col.-~unication ~vitll the buffer, the buf~er wi.ll ~lso becor.le colder. I~o~ever the bu~'fer ~/ill resist this . fall in temperature in two ways: firstly by releasing its own sensible heat as its te~peraturc ~alls to~Yards the freezing temperature of the ~u~fer and belo!v; and secondly when its te~.perature ~alls sli~htlybelow the frePzin~ point it will be~in to ~reeze and, in doing -. SO, it ~7ill release its latent heat o~ fusion to the C2 in the supply bottle and so arrest the ~all in te~perature of the C02 at a le~el not ~ar belo~J the freezin~ point o~ the bu~fer thus maintaining the pressure ' o~ the C~2 and ~he power o~ the motor at a se~sibly ~on~tant level.
-At the ènd o~ the po-~er run the buf~er will furthe~.lore ~elt again as heat fro~ t.~e surrounding environr.lent ~lo~vs naturally into it. This provides a further store of hea~ ener~y for tlle next run o~ the motor and this process may of course be repeated inde~initely.
I The vessel may if desired be dstacha~le from ~he re~t of :J the rnotor. It may be disposable or re~illable. I~ ' desired, 6as supply a~ ara~us may be provided to convert i ~ 3~1~'7~
an e~istinV I~OtOr into one .~cor~ o the prcs~nt invclltion. I'notllcr possibility is to I)lovid~ ~s supply appa.~atus ~ icll may ~e used in~el~ch~n~eably witl more than one motor. 'uch ~as supply ~pparatus l.lay have a pas~6e in therMal cor~ ullicatioll with a con~ainer for buf~cr substance, By app~opria~ly selectin~ the buffer su~s~ance a suitable-deg:ree o~ sui~erheating may thereby be achieved.
According to anot;ler aspect of the present invention there is provided gas supply appara~us ~or use i~
asSoCiatioD r~ith a r.lotor to constitute the r~otor accordin~ ~o the first aspect of the invention, the gas supply apparatus comprisin~ a vessel containin~ ue~ied .
gas under pressure Or capable o~ bein~ charged with ue~ied ga5, a pæssa~e in cor~mu~ication at one of its ends with ~he vessel or being capab~e of being placed in.
co~unication ~tith the vessel by operation of ~alve or other ~eans, which apparatus has in heat co~ductive relations~lip with the vessel or the passage or both, at least one container holding or. capable of being cllær~ed ~ith buf~er su~stance t as hereinbefore de~ined), an&
adaptor means capable o~ connectin~ the ~as supply æpparatus to the motor sueh that the outla-t o~ tlle passa~e cor~ unicates with the chamber(s~ ~vhich housets) the rotary ~r reciprocable element(s) OI the motor~
I~ desired, the passa~e n~ay ~orm part o:f a su~erheater.
Alternatively, the superheater r,iay be provided ln the ~ody OI th~ motor itself.
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~dvanta~eo~sly the n~ )tor is sllape~l to match th~
I.~OWltill~ flall~e of tlle r.:otor so th~t tl~e Motor r,lay- be Ii~ed to thc a~aptor. The adalltor is next p~ovided tvith one soclcet ~or a plurality o~ socl;ets, in the case of existill~ motors with more th~n one cylinder3 so that the inlet feed tubin~ of the e~istin~ motor ma~ be easily soldered into t}liS soclcet. ~l~ernatively one ~ ay provide ~1 'O' rin~ or olive connection bet~7een the inlet feed pipe and the adaptor, in the l~nown manner of pipe couplin~s. The adaptor is also advantageously provided with r.leans (preferably sealcd by an 'O' ring) to provide a gas-ti~ht connection with the ~as supply apparatus, preferably in the form of a screw couplin~
or snap couplinv7 By this means, once the adaptor has been connected and ~ixed to the motor, the motor may be quickly fitted to the ~as sup~ly a~ratus, and repeatedl~ removed and recouplcd i~ so desired. ~nis facility is particularly desirable in its appllcation to model ~ircraft and toys, since it allows one motor to be ~uickly moved fror.l one ~odel or to~ to another as -desired, each ~odel or toy havin~ its o~vn individual gas supply apparatus permanentiy ~ittedO The adaptor may be a m~le or ~e~ale-~lember on the ~as suppl~J apparatus , . .
adapted to ~ate with a complimentary female or male me~ber on the motor.
I~ desired the vessel may be a sealed bulb con~ainin~
liquefied gas~ me motor or ~as supply apparatus may have piercin m~ans capable of brealcin~ the seal and thereby placing the vessel in co~nunication ~ h the passage. ~ccordingly, a yet further aspect of the ~ . .8 -E:r~scnt invt?ntion l~rovitles ~,~s surnl~ a~ .ar.ltus for associL~tion with ~ posit;ivc-disr)l~ccrent or turbille motor to con.sl;itnte a r.~otor accordinb to the first asl ect o:e tll~ in~ention, the ~r~s 5u~?pl~y ~pp~.ratus includin" ~ holder ~cl~pted to :receive a vessel containin~ liquefied ~as, the holder havlng on its ner surf ace: .
ta~ a closeLl or re~illable jacl;et contD.inin -~ or adapted to be char~ed ~with buIfer subst~nce ( as hereinbefore de~ined) such that on insertion o~ the vessel into the holder, the j acliet cor.;es - into heat-con&uctin~ relationship ~ïith the ve~sel; or .
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(b) sealing means adapted to n~ie a liquid-ti~ht . se~l with the vessel, the holder being shaped and constructed SUC'L1 tllat it is capable of .definin~ with the Yessel ~ jacket ~or bu~Ier . .
substance ( ~s hereinbeIore defined) around the vessel, and a body mer,lber or body asser.l~ly e~agea~le Wit~l the holder and the ~lotor or an adaptor connected to the ~.iotor, the body ~ember .. . .
. or body assem'~ly having a passa~e able to be . . `placed in con~unication at orle oi lts ends with the ullage space o~ the vessel and at its other end with a cha~nber (or chambers3 housin~ the . ~ .
-~ rotary or reciprocable eler.lent(s) o~ the n~otor.
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The motor or gas supply apparatus zccordin~ to the illvention may i~e~sold with tlle or each container cllarged with bu~Ier substance. Alternatively, the or ezch cont~iner may be , .
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adapted to be charged with buffer substance by the user of the motor.
The container may conveniently comprise a jacket surrounding the vessel. It is advantageous to encourage the flow of heat by the use of metal foam to carry the buffer - (especially when the buffer is in a cavity or jacket surrounding the vessel) or partly to fill the container or jacket holding the buffer with fine metal mesh, gauze, filings, - swarf, powder or woven or knitted metal wire so as to form a latticework of heat flow paths throughout the buffer. It is advantageous to arrange for the length of these heat flow paths within the latticework to be as small as possible as a means of increasing the rate of heat transfer, together with the use of the smallest convenient size of pocket or voids containing the buffer. The or each container may alternatively be situated in the vessel itself. A closed tube or small capsules may for example be used. The size of such capsules should preferably be below 1 mm diameter and preferably as small as 0.2 mm diameter.
In the case of disposable or other supply bulbs (for example bulbs of C02 sold under the trade mark SPARKLETS) which are to be enclosed within a jacket containing the buffer, it is desirable either to make such bulbs from a high thermal conductivity material which is also corrosion resistant (such as aluminium or one of its alloys) or, if it is made of an inexpensive but corrodible material such as steel (as in the case of standard "Sparklets" bulbs), to............. O
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plate or paint or coat the surface of the supply bottle with a corrosion-resisting material which is also a good conductor of heat. Conventional paints are not satisfactory in this respect being poor conductors of heat and it is advantageous to use a paint which is, firstly, applied as a coating of less than 0.1 mm (and preferably less than 0.05 mm) in thickness and secondly, which has a thermal conductivity of at least 0.002 cal/sec.cm.C and preferably nearer to 0.005 cal/sec.cm.C, after application and subsequent drying or curing. This may be achieved ~ith paints containing finely divided metals such as aluminium powder, or finely divided metal oxides such as 2inc oxide or beryllium oxide or finely divided graphite such as that sold under the trade mark "Shawinigan" Black in which the graphite isi in the form of tiny needles which tend to link up to form heat flow paths, or other fillers which allow the thermal conductivity to reach the figures specified above.
Alternatively the tank may be made of inexpensive material such as plastics, and, because such material may not conduct heat very effectively, the buffer may be held within the vessel in a closed tube or in small capsules.
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A preferred way of achieving an effective degree of superheating in accordance with the invention is to arrange for the passage to be so adapted that it causes, in operation of the motor, a pressure drop of more than 10% of the saturation pressure of the liquid gas at the prevailing temperature, whereby the speed of the motor is able to be stabilised. Thus, the passage may for at ~ . . . . . . . . . . . . . . . . . . . .
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, leas1; part oI its le~ dcLine a tOl'tUOUS or ~:Jin~ G
patll for 1;h~ :Elo-~ o eval~or~t~(l GaS fror~1 the vcssel to the ;!~otor. I~t least part o: t;lle tortuolls or r,~linclin~
path is pre:Eer;lbly ill heat-collductivc r~latiorls;lil) with a container holding or capable of bein~ char~d with buI:~er substance. Preferal~ly, the bufIer sul~stance in thermal contact ~Yith tlle superheater has a freezin~
point ~,reater than tnat o~ the bu:E:Eer sulJstance in ther~al contnct ~ril;h the vessel. The passage may at least in part be de . ined by coile~l tubing. The tubing .
may ha~Je a len~th o~ fror.l ~ to 1 metre an(l a bore of up . to, say, 0!25 mm. By way o~ ex~mple, ~as boiled off at a little belo~Y 0C fron~ a vessel bu~ered ~ ith ~vater may then be superheated to approximately 10C by means - o~ an acetic acid (!:~ about 12C) water--bu~e~.
_. In addition the lon~; ~ine-bore superheæter - coil causes a pressure reduction o~ typic~lly 150 psi .
(compared with typic~lly 0.2 p.s.i. in previously l-nown ., ~
l~ I desi~ns~, ~qhich helps to brin~ about the required degree .~ o~ superheQtin~ heat trans~er and ~hichJ furtherr.. ore, causes any incipient slo~.ving dow~ of the motor to be - co~pensated ~or by a lessenin~ o~ such pressure reduction ~ e. it c~uses an increase in gas supply pressure to the - ~otor) ~hlch tends to stabilise ~he motor speed and power.
. Bl~ernatively the pressure drop May be e~fected by providing a porous pla~3- or plug in the passage, Bxistlll~; C02 ~otors, ~herl linked ~ith gas supply apparatus . . employi~ bufferin~ of the Yessel and superheater can :j . -. , - .. ,., .:.. . , ~ : . . ~ , :. . :
d~v~!lc~p tl~rcc to fi~c ti.lles as mu~ o~;cr, lli~her arld n~Ol`C COI~St~rt r.p.m., ~ree~om Iror) icin~, cond~nsation and risk of motor &a~.r.l~e, and ~cqn~te ~er~o~.la~ce in cold ~leathcr, The motors ~ccordinc,~ to the inventioll may be eMplo~e~
in such t'.lin~s as po~:er tools (domestic and industrial), hed~re-trir.~ers, portable chain saws, toys, ~odels, dentists' drills, lawn mowers and light auto~.otive vehicles. They are part.icularly suitable ~or use in toy or model aeroplanes. Particular a~vanta~es of the ~otor accortlin~ to the inventioll include its avoidance o~ the need ~or a trailing electrical power lead ~as in domestic power tools etc) or co~pressed-air hose ~as in industrial power drills and garae equi~.ents~; the rapidity with which it may be recllar~ed (a few seconds ' to re~ill with ~as versus several hours ~o rechar~e ba~terles -); its smaller size and wei~ht; its lac';
oi any ~ire risk, electrical dan~er or radio inter~erence;
its a~oidance of the use of toxic or dan~erous chemicals as in lead-~cid and other bat~eries; its lo-v cost o~
manu~ac~ure an~ of operation; its controllability o~
spe~ and power; and its ability to use sa:Ee natural gases (i.e. as found in~the clean at~os~here) which, after- use, are returned back to the atmosphere without pollution .
Suitable lique~ied. ~ases for .use with the ~otor may be cl~ssi~ied lnto tr~o distinct cate~ories: those wllich at normal ternl)eratures may be liquefied ~y pressure alone . . .
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(for example carbon dioxide); and those such as nitrogen which must be cooled below normal atmospheric temperatures before liquefaction is possible even under pressure.
Gases of the latter category must be stored in well-insulated tanks if they are to remain in the liquid state. Gases of the former category do not require to be kept cold in order to remain liquid and are therefore more easily handled and stored in the liquid state, which confers advantages of compactness, design simplicity and convenience.
Accordingly, the invention comprises a motor having in combination therewith apparatus for supplying to the motor gas evaporated from liquefied gas t said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas . evaporating from the liquefied gas is conducted into the motor, ~ and in heat conductive relationship with the vessel, at least - one container holding a buffer substance which during operation of the motor releases heat to the vessel and the liquefied gas therein, whereby the tendency of the evaporation of the lique-fied gas to cool the remaining liquefied gas in the vessel is at least partly counteracted.
Alternatively, the invention comprises a motor having ; in combination therewith apparatus for supplying to the motor : gas evaporated from liquefied gas, said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas , evaporating from the liquefied gas is conducted into the motor, ~ and, in heat conductive relationship with at least part of the i 1 1 ~ 14 -:: : , i .: .. , :
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passage, at least one container holding a buffer substance which during operation of the motor releases heat to evaporated gas as such gas passes through the passage, thereby raising the temperature of said evaporated gas.
The invention will now be described by way of example with reference to the accompanylng drawings of which:
Figure 1 is a longitudinal cross-section of a stored energy motor according to the invention, which motor has an - integral liquefied gas tank;
Figure 2 is a transverse cross-section on line X-X of the gas tank;
Figure 3 is a transverse cross-section on line Y-Y
showing the rotor and vanes used to expand and e~tract power from the gas.
Figure 4 is a longitudinal cross-section of a gas supply apparatus according to the invention incorporating means to increase motor power, reduce gas consumption and to stabilise and control gas pressure.
Figure 5 is a longitudinal cross-section of gas supply apparatus according to the invention containing a disposable supply bulb such as a "Sparklets" bulb.
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urc ~ is Ll lon~itu~ini~l croi~s~secti.on of ~1l a~aptor suiti~ble to a~ t ';no~ ypes oI existing l~o~el C02 motors to ~it the ~as supply a1~paratus shotvn in Fi~ure5 , ~i~ure 7 is a view in elevation of a typical e~;istin~
model C02 ~otor.
~Pith refexence to ~i~ure 1, the r;iotor has a tan~; (or .
. vessel) 33 whicll is de~ cd by shaped coupling rrembers 16 ancl 34 ~in screw threaded en~z~er.~ent ~ith a sleeve 3i5 .. ( oi' good hea ~conductive metzl. To en~ble it to be charged Witil iique~ie~ gas the r.~otor has a ~ill nozzle 1 whose lower end (as sho~vn) is mounted in the coupling member 1~ in a passage (or o~ening) 36 which com~unicates with the interior o~ the ti~ll; 33 by uay o~ an o~ifice 30 The internal sur~ace o~ the nozzle 1 has a ~rustoconical suri'ace ~ ~hich acts as an upper valve seat engaging elastoaleric plug 2.
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~ At the lower end (as sho~n) o~ the passage 36 is a lower : : ; .
frusto-conical valve seat 9 enga~eable ~Yith the plug 2 to seal irom ~he tank a gas space 10 of chosen ~olume `~ relative to that o~ the tan~ i~ communication with the ssa~e 3~ by way o~ a second orifice g. The gas space : . .
is deiined between.one end o~ the couplin~ mer.lber 16 a~d one ~lld o~ the cylindric~l body OI the motor, the coupling member 1G ~nd body 11 bein~ held in engagement by a slee~e 12 o~ heat conductive ~e~al.
To char~e the t~nk 33 with 9 say, liquid carbon dioxide, a refill cylindcr (not shown) containing liquid C02 is applied to the nozzle 1 ~Ivhereupon the plu~ is ~orceLI
down~vardis into en~er,lent ~ith the lo.ver val~e seat 9 to ' .
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place the -tank 33 in communication with the nozzle 1.
Liquid C02 thus ~lows into the tank 33 but not the gas space lO. The refill cylinder may be of conventional design. For example, it may operate in precisely the same manner as a butane cylinder for refilling cigarette lighters.
On withdrawing the refill cylinder9 the plug 2 is returned by differential gas pressure to engage the upper valve seat 4. Because of the provision of the gas space 10 the motor is able to be constructed such that it complies with the international legislation governing containers of compressed or liquefied gas. This legislation requires that not more than approximately 75% of the internal volume of the tank and motor assembly should be taken up by liquid C02, at 60F. The remaining 25% is -to be reserved for free gas space in order to accommodate expansion effects in hot climates. Thus, the ratio of volume of the gas space to that of the tank may be, for example, 25:75. When the charging is complete the maximum permissible ratio of 75%
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liquid to 25% gas will thus not be exceeded, As shown in Figure 1, the sleeve 35 has a circumferential recess 37 ln its outer surface. An outer sleeve of good heat conductive metal engages the outer surface of the (inner) sleeve 35 to define a closed cavity or (jacket) 3 for buffer substance 7.
When the jacket 33 is charged with the buffer substance (usually water) a small air space is left (see Figure 2) ,~ .
' to accommodate temperature-expansion effects. Elastomeric - sealing rings 39 and 40 are engaged between the sleeves to prevent leakage of the buffer substance. ;
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Satura-ted vapour evaporating from the tank 33 passes into the passage 36, -through the orifice 8 and into the gas space 10. It then en-ters a passageway 13 which is defined between the body 11 of the motor and -the sleeve 12. The sleeve 12 is in screw-threaded engagement with one end of the coupling member 16 and with one end of the body 11. The passageway 13 is helical and relatively long and narrow being defined between the screw threads on the sleeve 12 and those on the body 11, these screw-thread being suitably truncated. The adjacent ends of the body 11 and the coupling member 16 are spaced longitudinally ,apart from one another by a small distance to provide an entry for the vapour into the helical passageway 13.
The vapour enters the passageway 13 as shown by arrows 14 and makes its way to the motor via a needle control valve 15 and in doing so is heated to a temperature close to that of the sleeve 12 and the body 11 which 9 in the region of the engaging threads, are the warmest par-ts of the motor~ The gas also experiences a loss in pressure due to frictional pressure drop in the helical passageway 13 and this, combined with the gas ternperature rise, provides the gas with an adequate degree of super-heating.
-The coupling member 16 is preferably made of insulatingmaterial such as glass-reinforced nylon, so that the sleeve 12 and cylindrical body 11 are not cooled by thermal communica-tion with the colder tank. In order to enhance further the degree of superheating, the sleeve 12 is , : ~
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provided with a plurality of fins 18 which link with a metallic shroud 17 which serves as a heat collector. The motor has a shaft l9. If the shaft is provided with a small fan or propellor in order to induce a flow of air over the motor shell with its fins and shroud, the temperature o~ the metal around the passageway 13 will closel~ approach that of the ambient air and thus impart to the C02 gas a temperature close to ambient.
An alternative method of enhancing the degree of superheating comprises the provision of a cavity or jacket around the shell in a way similar to that shown in Figures l and 2 for the tank. In this case a buffer substance is chosen for the cavity around the motor shell so that its buffering temperature is equal to or slightly above the superheat temperature desired. Thus~ for instance, one could have a tank buffered at 0C by means of a water jacket and ~he motor buffered at 16~ ~y means of an acetic acid jacket.
The shaft carries a vaned rotor shown in Figure 3.
. The rotor comprises a conventional design in which a plurality
This invention relates to motors and to gas supply apparatus for use in association with motors.
Motors which run on liquefied gases are. known and have for instance been used to power model aircraft lusing sometimes a bottle. of pressure-liquefied carbon dioxide).
A major difficulty which arises with such motors is the progressive fall in gas pressure which occurs as gas flows ~rom the bottle or tank in order to drive ~he motor, and which limits the power of the motor to a rathPx .
low level. This fall in pressure is a consequence of the cool-ing of ~he gas as it iattemp~s to evapora~e from the liquid state in the s.upply bottle and to expand against ambient pressure during consumption by the motor. .This cooling effect becomes worse as one attempts to lncrease the speed and power of the motor and can even cause forma~ion . , , ~ , ~
of ice on the outside of the bottle~ Furthermore the cooling of thQ gas causes its density ~o increase with ~he result that gas consumption is increased undesirably.
A further disadvantage of exis~ing motors powered by . .
.vaporised gas arises because the gas taken from ~he bottlè for such e~isting motors is at or near the condition known as "saturation" with the consequence that, as soon as it is e~panded in the motor, i~
in~vltably condenses partly back into its liquid or even its solid state~ Apart fxom khe possibility o~ damage to the motor such condensation also causes a large lncrease ., . . .. ~ . . .... . . .
: ~ ' ' ' ' ' :" ' ' . - ' , ' ' ' . '' , '7~
in ~he sl~écil`i c volun~e oî the ~Yorking Llui~l an~ l;his requires ;hat the mc)tor shoulcl have a high exp.~llsiorl ratio in order adequately to expand tl~ ~vorkin~ fluid and so extract its avai lable ener~y, and this in turn leads to t11e need ~or an undesirably lar~e motor, or to an undesirably low charge volume (wllich reduces motor po~Yer), or to the need ~or excessively high rpm in order to secure sufficient power from the motor. One proposal ~or overcoming the problem of condensation o~ the gas in the motor is to superheat the gas be~ore it is used in the motor, that is to increase its heat at sensibly constant pressure, br to reduce its pressure at sensibly constant temperature (or any combination of these two processes).
Although the value of superheating has sometimes been recognised in existing motors, the usual technique of achieving it has been by leadillg the gas from the supply bottle through fine-bore metal tubing be~ore admission to the motor, this metal tubing usually bein~ coiled and positioned so tha* ambient air flows over the tubing during operation. (Existing motors are usually adapted to fly model planes and so have a propellor which blo~vs air over the n~etal tubing). This technique ~ives a small but si~nificant improvement in performance, though not overco~i~g the problem of ondensation, diseconomy, power loss and possible motor damage at high power settings and, being reliant on the temperature o~ the ambient air to provide the superheatinG, is not very effective in cold weather when the extent of power loss can be severe.
Moreover it does not give ~ significant expansion of the ~as as it passes to ~he motor.
According to a first asl)ect of the present invention there is provided a mvtor ~vhose reciproca~le or rotrary element(s) is (or are) a~a~ted to be driven by evaporated liquid gas, ~ -3-.
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the motor having associated therewith a vessel containing liquefied gas under pressure or being capable of being charged with lique~ied gas, a passage which af~ords communication between the ullage space of the vessel and the element(s) or which by operation of valve or other means is able to provide communica-tion between the ullage space of the vessel and chamber(s) which house(s) the element(s), and in heat conductive relationship with the vessel or the passage (or both), at least one container holding or capable of being charged with buffer substance (as hereinafter defined).
By the term "buffer substance" is meant a substance which undergoes a change in its physical, chemical crystallo-graphic or other state at a temperature between amhient temperature and the final operating temperature of the liquefied gas, the change of state then causing a release of heat, to the liquid gas or evaporated liquefied gas. This heat may be derived from its latent heat of fusion, or from its laten-t heat of vapour-isation, or from its heat of hydration, or from.an~ other effect which causes a significant release of heat at a certain falling temperature and which, advantageously, re-absorbs that heat reversibly as the temperature rises again. Substances from which the buffer substance may be selected include a very large number of alternatives (as listed for instance in the CRC "Handbook of Chemistry and Physics", 55th Edition, Pages B 63 to B-156, B-243 to B-247, C-639 to C-658, and C-680 to C-719.) ~ 4 ~
.. .
'` h~. ' Motors making use of this buff.ering technique are referred to herein as "s~:ored ener~y motors" because their buffer substances effectively store heat energy which is released.
to the working fluid for conversion into power as the motor runs. In the case of stoxed energy mo~or~; running on CO~ at normal ambient temperatures, suitable buffers include acetic acid (MP circa 16C), formic acid (MP circa 8C), and water (MP OQC), and mixtures of these materials i~ which allow other melting points to be achieved: for instance a mixture of 99~ acetic acid and 1% water by o volume has a meltlng point near 10 C which is useful for stored energy motors ~unning in temperate climates~
The above buffers are attractive by virtue of their ~iigh latent heats of fusion, whereby a relatively small amount of buffer substance suffices (eg o~e gram o~ buffer per thxee or four grams of C02 in the case of a water buffer).
The above buf ~ers are also very inexpensive and so may b~ used, ~or example, in disposable C02 bulbs. Anoth~r desirable quality of the buffer subst~nce is a high~ermal conductivity, to facilltate heat flow from the buffer into the Co2(orother gas being used), and into the buffer from the surrounding environment. Water is particul'arly good in this respect. The function of the bu~fer substance in thexmal contact with the vessel is to prevent the liquefied gas from sustaining a serious fall in temperature and pressure as it evaporates~ The bufer achieves thls function by releasing heat to the liqueied gas as its tempera~ure attempts to fall. For example the . ' . . ' ' .
. , . . -- 5 --, . .
. , :
Inl:Cfcl r~ay b~ a subst~ ce ~llich has a r~cltin, l~oill t oL
O to 10C .md ~hicl~ is there~ore in its li~lui(l st~te at norl.lal ,u,~ nt ter.lperatur~s, Thell, in the case o-F
a C02 ~otor fol e,;~mple (tllou~,h the invent~on is - equally applicable to other ~ascs), as the C02 gas is drawn OII to drive the motor tlle rer.lainin~; C02 in tlle bottle ~Yill bccohe colder l~ut, bein~ in ~ood t~lermal col.-~unication ~vitll the buffer, the buf~er wi.ll ~lso becor.le colder. I~o~ever the bu~'fer ~/ill resist this . fall in temperature in two ways: firstly by releasing its own sensible heat as its te~peraturc ~alls to~Yards the freezing temperature of the ~u~fer and belo!v; and secondly when its te~.perature ~alls sli~htlybelow the frePzin~ point it will be~in to ~reeze and, in doing -. SO, it ~7ill release its latent heat o~ fusion to the C2 in the supply bottle and so arrest the ~all in te~perature of the C02 at a le~el not ~ar belo~J the freezin~ point o~ the bu~fer thus maintaining the pressure ' o~ the C~2 and ~he power o~ the motor at a se~sibly ~on~tant level.
-At the ènd o~ the po-~er run the buf~er will furthe~.lore ~elt again as heat fro~ t.~e surrounding environr.lent ~lo~vs naturally into it. This provides a further store of hea~ ener~y for tlle next run o~ the motor and this process may of course be repeated inde~initely.
I The vessel may if desired be dstacha~le from ~he re~t of :J the rnotor. It may be disposable or re~illable. I~ ' desired, 6as supply a~ ara~us may be provided to convert i ~ 3~1~'7~
an e~istinV I~OtOr into one .~cor~ o the prcs~nt invclltion. I'notllcr possibility is to I)lovid~ ~s supply appa.~atus ~ icll may ~e used in~el~ch~n~eably witl more than one motor. 'uch ~as supply ~pparatus l.lay have a pas~6e in therMal cor~ ullicatioll with a con~ainer for buf~cr substance, By app~opria~ly selectin~ the buffer su~s~ance a suitable-deg:ree o~ sui~erheating may thereby be achieved.
According to anot;ler aspect of the present invention there is provided gas supply appara~us ~or use i~
asSoCiatioD r~ith a r.lotor to constitute the r~otor accordin~ ~o the first aspect of the invention, the gas supply apparatus comprisin~ a vessel containin~ ue~ied .
gas under pressure Or capable o~ bein~ charged with ue~ied ga5, a pæssa~e in cor~mu~ication at one of its ends with ~he vessel or being capab~e of being placed in.
co~unication ~tith the vessel by operation of ~alve or other ~eans, which apparatus has in heat co~ductive relations~lip with the vessel or the passage or both, at least one container holding or. capable of being cllær~ed ~ith buf~er su~stance t as hereinbefore de~ined), an&
adaptor means capable o~ connectin~ the ~as supply æpparatus to the motor sueh that the outla-t o~ tlle passa~e cor~ unicates with the chamber(s~ ~vhich housets) the rotary ~r reciprocable element(s) OI the motor~
I~ desired, the passa~e n~ay ~orm part o:f a su~erheater.
Alternatively, the superheater r,iay be provided ln the ~ody OI th~ motor itself.
.
~3~.~5'~ ~
~dvanta~eo~sly the n~ )tor is sllape~l to match th~
I.~OWltill~ flall~e of tlle r.:otor so th~t tl~e Motor r,lay- be Ii~ed to thc a~aptor. The adalltor is next p~ovided tvith one soclcet ~or a plurality o~ socl;ets, in the case of existill~ motors with more th~n one cylinder3 so that the inlet feed tubin~ of the e~istin~ motor ma~ be easily soldered into t}liS soclcet. ~l~ernatively one ~ ay provide ~1 'O' rin~ or olive connection bet~7een the inlet feed pipe and the adaptor, in the l~nown manner of pipe couplin~s. The adaptor is also advantageously provided with r.leans (preferably sealcd by an 'O' ring) to provide a gas-ti~ht connection with the ~as supply apparatus, preferably in the form of a screw couplin~
or snap couplinv7 By this means, once the adaptor has been connected and ~ixed to the motor, the motor may be quickly fitted to the ~as sup~ly a~ratus, and repeatedl~ removed and recouplcd i~ so desired. ~nis facility is particularly desirable in its appllcation to model ~ircraft and toys, since it allows one motor to be ~uickly moved fror.l one ~odel or to~ to another as -desired, each ~odel or toy havin~ its o~vn individual gas supply apparatus permanentiy ~ittedO The adaptor may be a m~le or ~e~ale-~lember on the ~as suppl~J apparatus , . .
adapted to ~ate with a complimentary female or male me~ber on the motor.
I~ desired the vessel may be a sealed bulb con~ainin~
liquefied gas~ me motor or ~as supply apparatus may have piercin m~ans capable of brealcin~ the seal and thereby placing the vessel in co~nunication ~ h the passage. ~ccordingly, a yet further aspect of the ~ . .8 -E:r~scnt invt?ntion l~rovitles ~,~s surnl~ a~ .ar.ltus for associL~tion with ~ posit;ivc-disr)l~ccrent or turbille motor to con.sl;itnte a r.~otor accordinb to the first asl ect o:e tll~ in~ention, the ~r~s 5u~?pl~y ~pp~.ratus includin" ~ holder ~cl~pted to :receive a vessel containin~ liquefied ~as, the holder havlng on its ner surf ace: .
ta~ a closeLl or re~illable jacl;et contD.inin -~ or adapted to be char~ed ~with buIfer subst~nce ( as hereinbefore de~ined) such that on insertion o~ the vessel into the holder, the j acliet cor.;es - into heat-con&uctin~ relationship ~ïith the ve~sel; or .
.
(b) sealing means adapted to n~ie a liquid-ti~ht . se~l with the vessel, the holder being shaped and constructed SUC'L1 tllat it is capable of .definin~ with the Yessel ~ jacket ~or bu~Ier . .
substance ( ~s hereinbeIore defined) around the vessel, and a body mer,lber or body asser.l~ly e~agea~le Wit~l the holder and the ~lotor or an adaptor connected to the ~.iotor, the body ~ember .. . .
. or body assem'~ly having a passa~e able to be . . `placed in con~unication at orle oi lts ends with the ullage space o~ the vessel and at its other end with a cha~nber (or chambers3 housin~ the . ~ .
-~ rotary or reciprocable eler.lent(s) o~ the n~otor.
.~ .
The motor or gas supply apparatus zccordin~ to the illvention may i~e~sold with tlle or each container cllarged with bu~Ier substance. Alternatively, the or ezch cont~iner may be , .
57~
adapted to be charged with buffer substance by the user of the motor.
The container may conveniently comprise a jacket surrounding the vessel. It is advantageous to encourage the flow of heat by the use of metal foam to carry the buffer - (especially when the buffer is in a cavity or jacket surrounding the vessel) or partly to fill the container or jacket holding the buffer with fine metal mesh, gauze, filings, - swarf, powder or woven or knitted metal wire so as to form a latticework of heat flow paths throughout the buffer. It is advantageous to arrange for the length of these heat flow paths within the latticework to be as small as possible as a means of increasing the rate of heat transfer, together with the use of the smallest convenient size of pocket or voids containing the buffer. The or each container may alternatively be situated in the vessel itself. A closed tube or small capsules may for example be used. The size of such capsules should preferably be below 1 mm diameter and preferably as small as 0.2 mm diameter.
In the case of disposable or other supply bulbs (for example bulbs of C02 sold under the trade mark SPARKLETS) which are to be enclosed within a jacket containing the buffer, it is desirable either to make such bulbs from a high thermal conductivity material which is also corrosion resistant (such as aluminium or one of its alloys) or, if it is made of an inexpensive but corrodible material such as steel (as in the case of standard "Sparklets" bulbs), to............. O
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plate or paint or coat the surface of the supply bottle with a corrosion-resisting material which is also a good conductor of heat. Conventional paints are not satisfactory in this respect being poor conductors of heat and it is advantageous to use a paint which is, firstly, applied as a coating of less than 0.1 mm (and preferably less than 0.05 mm) in thickness and secondly, which has a thermal conductivity of at least 0.002 cal/sec.cm.C and preferably nearer to 0.005 cal/sec.cm.C, after application and subsequent drying or curing. This may be achieved ~ith paints containing finely divided metals such as aluminium powder, or finely divided metal oxides such as 2inc oxide or beryllium oxide or finely divided graphite such as that sold under the trade mark "Shawinigan" Black in which the graphite isi in the form of tiny needles which tend to link up to form heat flow paths, or other fillers which allow the thermal conductivity to reach the figures specified above.
Alternatively the tank may be made of inexpensive material such as plastics, and, because such material may not conduct heat very effectively, the buffer may be held within the vessel in a closed tube or in small capsules.
.; .
A preferred way of achieving an effective degree of superheating in accordance with the invention is to arrange for the passage to be so adapted that it causes, in operation of the motor, a pressure drop of more than 10% of the saturation pressure of the liquid gas at the prevailing temperature, whereby the speed of the motor is able to be stabilised. Thus, the passage may for at ~ . . . . . . . . . . . . . . . . . . . .
'.
J
, leas1; part oI its le~ dcLine a tOl'tUOUS or ~:Jin~ G
patll for 1;h~ :Elo-~ o eval~or~t~(l GaS fror~1 the vcssel to the ;!~otor. I~t least part o: t;lle tortuolls or r,~linclin~
path is pre:Eer;lbly ill heat-collductivc r~latiorls;lil) with a container holding or capable of bein~ char~d with buI:~er substance. Preferal~ly, the bufIer sul~stance in thermal contact ~Yith tlle superheater has a freezin~
point ~,reater than tnat o~ the bu:E:Eer sulJstance in ther~al contnct ~ril;h the vessel. The passage may at least in part be de . ined by coile~l tubing. The tubing .
may ha~Je a len~th o~ fror.l ~ to 1 metre an(l a bore of up . to, say, 0!25 mm. By way o~ ex~mple, ~as boiled off at a little belo~Y 0C fron~ a vessel bu~ered ~ ith ~vater may then be superheated to approximately 10C by means - o~ an acetic acid (!:~ about 12C) water--bu~e~.
_. In addition the lon~; ~ine-bore superheæter - coil causes a pressure reduction o~ typic~lly 150 psi .
(compared with typic~lly 0.2 p.s.i. in previously l-nown ., ~
l~ I desi~ns~, ~qhich helps to brin~ about the required degree .~ o~ superheQtin~ heat trans~er and ~hichJ furtherr.. ore, causes any incipient slo~.ving dow~ of the motor to be - co~pensated ~or by a lessenin~ o~ such pressure reduction ~ e. it c~uses an increase in gas supply pressure to the - ~otor) ~hlch tends to stabilise ~he motor speed and power.
. Bl~ernatively the pressure drop May be e~fected by providing a porous pla~3- or plug in the passage, Bxistlll~; C02 ~otors, ~herl linked ~ith gas supply apparatus . . employi~ bufferin~ of the Yessel and superheater can :j . -. , - .. ,., .:.. . , ~ : . . ~ , :. . :
d~v~!lc~p tl~rcc to fi~c ti.lles as mu~ o~;cr, lli~her arld n~Ol`C COI~St~rt r.p.m., ~ree~om Iror) icin~, cond~nsation and risk of motor &a~.r.l~e, and ~cqn~te ~er~o~.la~ce in cold ~leathcr, The motors ~ccordinc,~ to the inventioll may be eMplo~e~
in such t'.lin~s as po~:er tools (domestic and industrial), hed~re-trir.~ers, portable chain saws, toys, ~odels, dentists' drills, lawn mowers and light auto~.otive vehicles. They are part.icularly suitable ~or use in toy or model aeroplanes. Particular a~vanta~es of the ~otor accortlin~ to the inventioll include its avoidance o~ the need ~or a trailing electrical power lead ~as in domestic power tools etc) or co~pressed-air hose ~as in industrial power drills and garae equi~.ents~; the rapidity with which it may be recllar~ed (a few seconds ' to re~ill with ~as versus several hours ~o rechar~e ba~terles -); its smaller size and wei~ht; its lac';
oi any ~ire risk, electrical dan~er or radio inter~erence;
its a~oidance of the use of toxic or dan~erous chemicals as in lead-~cid and other bat~eries; its lo-v cost o~
manu~ac~ure an~ of operation; its controllability o~
spe~ and power; and its ability to use sa:Ee natural gases (i.e. as found in~the clean at~os~here) which, after- use, are returned back to the atmosphere without pollution .
Suitable lique~ied. ~ases for .use with the ~otor may be cl~ssi~ied lnto tr~o distinct cate~ories: those wllich at normal ternl)eratures may be liquefied ~y pressure alone . . .
. . ~ .
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(for example carbon dioxide); and those such as nitrogen which must be cooled below normal atmospheric temperatures before liquefaction is possible even under pressure.
Gases of the latter category must be stored in well-insulated tanks if they are to remain in the liquid state. Gases of the former category do not require to be kept cold in order to remain liquid and are therefore more easily handled and stored in the liquid state, which confers advantages of compactness, design simplicity and convenience.
Accordingly, the invention comprises a motor having in combination therewith apparatus for supplying to the motor gas evaporated from liquefied gas t said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas . evaporating from the liquefied gas is conducted into the motor, ~ and in heat conductive relationship with the vessel, at least - one container holding a buffer substance which during operation of the motor releases heat to the vessel and the liquefied gas therein, whereby the tendency of the evaporation of the lique-fied gas to cool the remaining liquefied gas in the vessel is at least partly counteracted.
Alternatively, the invention comprises a motor having ; in combination therewith apparatus for supplying to the motor : gas evaporated from liquefied gas, said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas , evaporating from the liquefied gas is conducted into the motor, ~ and, in heat conductive relationship with at least part of the i 1 1 ~ 14 -:: : , i .: .. , :
;: :. .: ~ : ;: , ;:, ; , . ..
:: .. . ; .; : .: - . , ;, : , ,: i . : . ... ; , .: - . . : :,: ~ : , , 3L57~
passage, at least one container holding a buffer substance which during operation of the motor releases heat to evaporated gas as such gas passes through the passage, thereby raising the temperature of said evaporated gas.
The invention will now be described by way of example with reference to the accompanylng drawings of which:
Figure 1 is a longitudinal cross-section of a stored energy motor according to the invention, which motor has an - integral liquefied gas tank;
Figure 2 is a transverse cross-section on line X-X of the gas tank;
Figure 3 is a transverse cross-section on line Y-Y
showing the rotor and vanes used to expand and e~tract power from the gas.
Figure 4 is a longitudinal cross-section of a gas supply apparatus according to the invention incorporating means to increase motor power, reduce gas consumption and to stabilise and control gas pressure.
Figure 5 is a longitudinal cross-section of gas supply apparatus according to the invention containing a disposable supply bulb such as a "Sparklets" bulb.
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s~
urc ~ is Ll lon~itu~ini~l croi~s~secti.on of ~1l a~aptor suiti~ble to a~ t ';no~ ypes oI existing l~o~el C02 motors to ~it the ~as supply a1~paratus shotvn in Fi~ure5 , ~i~ure 7 is a view in elevation of a typical e~;istin~
model C02 ~otor.
~Pith refexence to ~i~ure 1, the r;iotor has a tan~; (or .
. vessel) 33 whicll is de~ cd by shaped coupling rrembers 16 ancl 34 ~in screw threaded en~z~er.~ent ~ith a sleeve 3i5 .. ( oi' good hea ~conductive metzl. To en~ble it to be charged Witil iique~ie~ gas the r.~otor has a ~ill nozzle 1 whose lower end (as sho~vn) is mounted in the coupling member 1~ in a passage (or o~ening) 36 which com~unicates with the interior o~ the ti~ll; 33 by uay o~ an o~ifice 30 The internal sur~ace o~ the nozzle 1 has a ~rustoconical suri'ace ~ ~hich acts as an upper valve seat engaging elastoaleric plug 2.
,,J . ~
~ At the lower end (as sho~n) o~ the passage 36 is a lower : : ; .
frusto-conical valve seat 9 enga~eable ~Yith the plug 2 to seal irom ~he tank a gas space 10 of chosen ~olume `~ relative to that o~ the tan~ i~ communication with the ssa~e 3~ by way o~ a second orifice g. The gas space : . .
is deiined between.one end o~ the couplin~ mer.lber 16 a~d one ~lld o~ the cylindric~l body OI the motor, the coupling member 1G ~nd body 11 bein~ held in engagement by a slee~e 12 o~ heat conductive ~e~al.
To char~e the t~nk 33 with 9 say, liquid carbon dioxide, a refill cylindcr (not shown) containing liquid C02 is applied to the nozzle 1 ~Ivhereupon the plu~ is ~orceLI
down~vardis into en~er,lent ~ith the lo.ver val~e seat 9 to ' .
5~
place the -tank 33 in communication with the nozzle 1.
Liquid C02 thus ~lows into the tank 33 but not the gas space lO. The refill cylinder may be of conventional design. For example, it may operate in precisely the same manner as a butane cylinder for refilling cigarette lighters.
On withdrawing the refill cylinder9 the plug 2 is returned by differential gas pressure to engage the upper valve seat 4. Because of the provision of the gas space 10 the motor is able to be constructed such that it complies with the international legislation governing containers of compressed or liquefied gas. This legislation requires that not more than approximately 75% of the internal volume of the tank and motor assembly should be taken up by liquid C02, at 60F. The remaining 25% is -to be reserved for free gas space in order to accommodate expansion effects in hot climates. Thus, the ratio of volume of the gas space to that of the tank may be, for example, 25:75. When the charging is complete the maximum permissible ratio of 75%
. .
liquid to 25% gas will thus not be exceeded, As shown in Figure 1, the sleeve 35 has a circumferential recess 37 ln its outer surface. An outer sleeve of good heat conductive metal engages the outer surface of the (inner) sleeve 35 to define a closed cavity or (jacket) 3 for buffer substance 7.
When the jacket 33 is charged with the buffer substance (usually water) a small air space is left (see Figure 2) ,~ .
' to accommodate temperature-expansion effects. Elastomeric - sealing rings 39 and 40 are engaged between the sleeves to prevent leakage of the buffer substance. ;
' ,'' 1. .
, . , ,, .. , . . . ~ . . .
5~7~
Satura-ted vapour evaporating from the tank 33 passes into the passage 36, -through the orifice 8 and into the gas space 10. It then en-ters a passageway 13 which is defined between the body 11 of the motor and -the sleeve 12. The sleeve 12 is in screw-threaded engagement with one end of the coupling member 16 and with one end of the body 11. The passageway 13 is helical and relatively long and narrow being defined between the screw threads on the sleeve 12 and those on the body 11, these screw-thread being suitably truncated. The adjacent ends of the body 11 and the coupling member 16 are spaced longitudinally ,apart from one another by a small distance to provide an entry for the vapour into the helical passageway 13.
The vapour enters the passageway 13 as shown by arrows 14 and makes its way to the motor via a needle control valve 15 and in doing so is heated to a temperature close to that of the sleeve 12 and the body 11 which 9 in the region of the engaging threads, are the warmest par-ts of the motor~ The gas also experiences a loss in pressure due to frictional pressure drop in the helical passageway 13 and this, combined with the gas ternperature rise, provides the gas with an adequate degree of super-heating.
-The coupling member 16 is preferably made of insulatingmaterial such as glass-reinforced nylon, so that the sleeve 12 and cylindrical body 11 are not cooled by thermal communica-tion with the colder tank. In order to enhance further the degree of superheating, the sleeve 12 is , : ~
, ~s~s~
provided with a plurality of fins 18 which link with a metallic shroud 17 which serves as a heat collector. The motor has a shaft l9. If the shaft is provided with a small fan or propellor in order to induce a flow of air over the motor shell with its fins and shroud, the temperature o~ the metal around the passageway 13 will closel~ approach that of the ambient air and thus impart to the C02 gas a temperature close to ambient.
An alternative method of enhancing the degree of superheating comprises the provision of a cavity or jacket around the shell in a way similar to that shown in Figures l and 2 for the tank. In this case a buffer substance is chosen for the cavity around the motor shell so that its buffering temperature is equal to or slightly above the superheat temperature desired. Thus~ for instance, one could have a tank buffered at 0C by means of a water jacket and ~he motor buffered at 16~ ~y means of an acetic acid jacket.
The shaft carries a vaned rotor shown in Figure 3.
. The rotor comprises a conventional design in which a plurality
2~ of vanes 21, advantageously made of oil-filled polyethylene plastic tinjection moulded~, slide in slots in the rotor 22 which may advantageously be made by injection moulding of oil-filled acetal resin (or vice versa). The body ll of the motor has an eccentric bore 23 defining a chamber for the ~ rotor 22. The vanes 21 are biased outwards in the eccentric '~ bore 23 of the body ll either under the action of vane spxings 24 '~,t, or by gas pressure fed vi~ suitable small b~leed holes (not shown) to the i:nward edge of the vanes 21.
: -~
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, . ,,. ,.,,. ,. ...... , ~, . , . . , ~, . . ..... . .
- : - . . : ~ . -, , . , , .. :,::, ,, . - . :.: : .... .. :
S'7&~
The superheated gas, having first been throttled to a greater or lesser degree by the adjustable needle control valve 15, enters the chamber 23 via an inlet port 25, drives the vanQd rotor as it expands, and finally exhausts via port 26.
Prevention of escape of gas acxoss the faces of the vaned rotor may be achieved by the provision of two-face sealing discs 29, of relatively soft and low frictional material such as PTFE or oil-filled polyethylene, which are pressed against the faces of the vaned rotor by means of an'O' ring 30 or other compressible part such as a spring or spring-washer. The peripheries of the faces of ~he Rotor 22 preferably are provided with sli~htly raised rims (similar to the rims of coins~ which wear into ~he face sealing discs and so inhibit thP escape o~ gas across the faces of the vaned -rotor. The ' O' ring 30 also prevents escape of gas sideways from the pexiphery of the vaned rotor assembly ~where it meets the e~centric bore 23) and also ~eing ini~lally compressed, expands , , .
as wear occurs in the vaned rotor and face sealing discs s~ as to take up tha~ wear and prevent gas leakage pa~hs paths from d3veloping~ . -Higher ~o~or powers and greater eneryy stora~e for a given amount of working fluid an d buffer substance, and greater control and constanc~ of pxessure and motor power as the tank is~ emptied, is achievable by ~he al~erna~lve tank assembly shown in Figure 4. Th~s desi~n is of ~alue in the larger-power and longer-duration-power applicatlons such as lawn mowers, moped motors and light automotive motors, and in applica~ions requiring hlgher power-to-weight ' . ... ~.' , ' ' .'. '' . . : ~. ' . ' ' ' ' ., . .. '' , I ' ' '7~
ratios and lower gas consumption such as airborne power devices; it is described as follows:
A buffer substance 133 is held in a container 134 prefexa~ly of metal of high thermal conductivity and low weight such as aluminium alloy or magnesium alloy. The container, or a part thereof, has integ~al therewith an extension at one end which is in the form of a yoke 135. The yok~ 135 has on its inner surface a step 14~ and thQrefore has cylindrical por~ions 136 and 148 of narrower and wlder bore respec~ively. Inside the yoke 135 and preferably clos~ly-fitting with, and frictionally engaging, the portion 136 of narrower bore so as to provide good thermal communica~ion with the yoke.135 ~s a metal block 137 (or other form of thermal pick-up) which can be txansla~ed along the axis of the yoke 135 in to positions in which its.
outer surface makes greater or less physical contact with the innex surface of the yoke 135. By this means the surface area of the boundary across which heat may flow from the yoke l35 to the metal block 137 (which is preferably also of metal of high thermal c~nductivity) can vary from zero up to a maximum as the metal block moves leftward in Figure 4 Any radial clearanc~ between the metal block : - .
- ` 137 and the yoke 135 may advantageously be filled with a grease of high thermal cond~ctivity,(for example silicone grease having zinc oxide dispersed therein) in .
order~ to improve heat flow.
~he metal block acts as a bearing for one end of a rod . : of material of high thermal conductivity or a heat pipe 45Lwhis~exte~ aftward ~as shown? through a 1exibl~
dlaphragm 138 and a wall 147 integral with part of a tan~
:~13tj3LSi~7~
139, into the tank 139 itself. The ~iaphr~l has an inner marginal portion 1~9 held in enga~ement bet~veen the heat ~ipe or rod 140 and the meral block 137 and an outer marginal poxtion 150 held in engage~ent betvleen *he vall ) .. . . .
~ , ,<
. . .
: .
. .
. .
. ~ .
:. ~
. J
. :~ ' .
5'7~
i~7 ~ f~ard (~s SilO'.III) f~cc of an in\~arcl projecti~ll 151 ~lorn a hollo:v ~,~n~rally cylillc'ric~l cou~ r.l~G~oe~ in s~ threa~cd cnt,a~;er,ellt ~ith the tanl; 13~. Li.q~ icc:l ,.,~;, is aL~ilc to pass throut,:~ ~n a~erture in tllc wall 147 tl~rou~;h t;'nich the lleat pipe (or rod) 1~l0 e,;te~ds ~nd t:~erehy the clia~hr~ 138, in e~fect, acts ?~S a closure ol; wa:ll o~ t}~e tanl;.
The le:Et~iard end ( as sho~ ) OI the hcat pii,e ( or rod) 14d is supported in a line~r bearing 141 Iorr,lin~ part o~ a couplin~ ~eM'~er 11~) so that the heat pipe (or rod) may ~e translated l~ftward or ri~htward. A re~ion of that part of the heat pipe (or ro~) that is in the t~nl; 139 has a plurality of ~ins 145 ~ihich m~y be axial or r~ial as s~own in.~igure ~ aad ~lhich e~tend int~ the liquefied ~as in tlle tank 139. This aXr~n~emen~
facilitates flo~ o~ heat ~rom the he~t pipe (or rod) 140 into the tan~: 139.
Around the heat pipe 1~0 in the tank 139 is a co~pression sprinV 1~2 so arran~ed as to apply a leIt~Y~I~d Iorce on the heat pi~e asser.~bly, and scale~ so that when ~as pressure in the tan~ is at the desired level the metal block 13~ is approxirilately in the positio~ shown in Fi gure 4 .
The.yol;e 135 advanta~eously h~s an e~:ternial thread 143 whicl~ en,,ages a cor.lplementary i~ternal threiad of the couplin~, member 14~. The coupling ~.ernber 1~ is pre~erably o~ therr.l~lly~ sulatin~ r~1aterial such as ~lass-reinIorcecl uylon so ~s to prevent undesirable flow o~ heat ~rom the contain~x 134 to the t~2llr 139.
.. . .
~l 22 -~.~.. ~ . . . .... .
'' ' .' ;; ' ' '' ' ' ' :~ , . : . : , , ' 7~
The engaging threads between the coupling member 144 and the yoke 135 allow the yoke 135 to be adjusted so as to provide greater or lesser thermal coupling between the inner surface of the yoke 135 and the metal block 137. This allows external adjustment of the controlled gas pressure in the tank 139 and thus of the power of a motor which can be connected to the let hand end (as shown) of the coupling member 116 in a manner ~imilar to that shown in Figure 1.
The function of the tank assembly shown in Figure in stabilising gas pressure will now be apparent as follows:
Any withdrawal of gas from the tank 139 will initially cause a slight fall in both the temperature and the pressure of the contained gas, and thus a fall in temperature of the left hand end of the heat pipe or metallic rod 140. The control spring 142, because of the said fall in tank pressure, will thus cause the heat pipe assembly to moveleftward, increasing the thermal contact area between the metal block 137 and the yoke 135 which, being warmer than the now-cooling heat pipe assembly, will convey more heat into the heat pipe or metallic rod and thence via the fins 145 into the liquid gas, thus restoring and regulating its temperature and pressure and causing the diaphragm 138 to flex outwardly and return the heat pipe (or rod) rightwards (as shown).
An equal or greater advantage of this design of tank assembly is its ability to control the heat flow from a much larger store of heat. Thus, even if the buffer substance 133 is much hotter than the tank 139 and its contained liquid gas, heat flow into the liquefied gas. . . . . . . . . . . . . . .
,~
, . . . ~ . . . , , j ~ . . :
will be regulated so as to maintain the desired gas pressure and not allow it to rise undesirably and cause a wasteful increase in gas consumption. The buffer siubstance may therefore be heated above ambient temperature before use, so as to store a greater amount oE heat energy which, during later use, is transferred to the working fluid and converted ; to useful energy in the motor.
In addition, the arrangement allows the generation of gas pressures much higher than would be achieved at ambient temperature and, provided that the motor has an adequate expansion ratio, this permits a marked reduction in gas consump-tion for a given power output, or a large increase in power output at the same gas flow.
To permit these greater amounts of heat storage it is desirable to pre-heat the buffer substance before use and this may be accomplished for instance by either an electric element or an electrical heating jacket 156 preferably fitted with a thermostatic cut-out. If intended as auxiliary power to an I.C. engine, the buffer container may be kept hot by means of the hot exhaust or other engine heat (eg the cylinder block). In all such cases it is usually desirable to thermally-insulate the tank and buffer container so that the stored heat does not leak away to the environment. Referring ,~ to Figure 5, a disposable supply bottle or bulb 201 containing C2 i~shown partly emptied) and painted on its outside surface with a thermally-conducting paint has a small oil-soaked `' pad 2Q2 positioned immediately on the inside of a closure diaphragm 203. The supply bulb 201 is shown inserted in a holder 204 which is advantageously made of injection-moulded glass-reinforced nylon and which is . . . . . . . . . . . . . . . . .
i ~ .
:
, , ~ ; , , , ;
6~57~3 provided with a lining 205 of metallic foam or mesh containing a first buffer substance 206 if the bulb contains ~g o~ CO2, preferably which comprises approximately 2 grams of water.
The le~ward end (as shown) of the holder 204 is provided with a female thread which engages with the male thread of a body member 207, and this thread not only supports the holder 204 but also allows the closure diaphragm 203 to be punctured by a hollow piercing needle 208 when it is desired to energize the apparatus by increasing the engagement o~ the threads.
The holder 20~ is sealed against loss of the first buffer sub-stance 206 by means of an '0' ring 209 and the neck of the supply bulb 201 is sealed against leakage of the CO2 after puncturing by means of an '0' ring 210 about the neck of the bulb 201. The piercing needle 208 is held in the body member 207 by means of a nut 211 and sealed by an '0' ring 212 and soldered to a tube 213 which is coiled within a superheater chamber 214 and which terminates with a soldered connection-to a probe 215.
The superheater chamber 214 in this embodiment is housed between an end member 229 and the lefthand end face (as shown) of the body member 207O In this embodiment it may contain 1.5 grams of 99% glacial acetic acid/1%/water (by volume) which comprises a second buffer 216 and ~hich assists the superheating process to - a vapour temperature of approximately 10C. A coil ratainer 217 in the form of a disc of plastic sheet (such as "Cobex" R T M P~C
sheetl serves to contain the coils of the tube 213. The probe 215 is provided with '~' ring 218 and is pressed . . . . . . . . . .
. ~ ~
, :
:'1 ' ~ ~
into a housing 219 after the application of an adhesive sealant such as that sold under the trade mark "Loctite". The probe housing 219 is itself pressed and sealed into the end member 229 either using "Loctite" or possi~ly by moulding it into the end member 229 which, together with the body member 207, may advantageously be injection moulded in glass-reinforced nylon or acetal resin or similar plastics resistant to acetic acid. The superheater chamber may be sealed against loss of the second buffer 216 by means of an '0' ring 220 or alternatively sealed to the body member 207 by an adhesive sealant or by spin or friction welding. All metallic parts in contact with the second buffer 216 are desirably made of aluminium or stainless steel or ~; electro-plated mild steel when acetic acid is used; copper and copper containing metals such as brass are likely to corrode and are not therefore recommended.
- Referring to Fig 6 and Fig 7 it will be seen that the motor is provided with a mounting flange 221 and mounting screws 222. The adaptor shown in Fig 6 is so designed to marry with this mounting flange 221 and is provided with tapped attach-20 ment holes 223 positioned so as to accept the mounting screws 222 as indicated by the dashed lines, and thereby to allow the adaptor to be fixed to the motor. The leftward end (as shown~ oE the adaptor is provided with a socket 224 sized to take an inlet feed ; pipe 225 of the motor by means of a soldered connexion. The right-ward end (as ~hown) of the adaptor is provided firstly with a male - thread 226 which engages with a female thread in the leftward end , . , -' (as shown) of the housing 219 shown in Fig 5 so as to allo~ the motor plus adaptor to be . . . . . . . . . . . . . . . . . . . .
' "' ''" ' '" . '' " '' '; '' ` ' ~ '~ ';' " '' ."''' '' '' ' , ' "'.;'', ' " '~''' .' "." ' ''' ' '' ' " "" '' `'. ' "' ' , . ' . ' " ' " " ' ~ .' ~ "'-' . .'. ' ' ' , ' .' . ' . '' '. . '.' " ' ' ' ' ' ' "' " ' ' " ' ' ' ' " : ' ' .,:,'., ., . . , . ', ' ,. , ',' . ' ,',. ' . ' ,' ' ;'', . '': ' '.' ~ ,', ' " ' ." " ' ". ' ." ' ' " ' " ' , . .: - ' ' , . , ' . ,. . " " ' ,', , , , , '. ' ' ' ' ' . ' ~ ' ' '' ' ' , ' ' ~ ' ', ' :
s~
quickly attached to the probe, and secondly with a chamfered socket 227 which is designed so as to accept the probe 215 and at the same to compress and seal the '0' riny 218 o~ the end member in Fig 5.
The oil-soaked porous pad 202 enables the issuing gas from the supply bulb 201 to carry with it droplets of oil into the motor. This technique is particularly useful where disposable supply bottles such as "Sparklets" (trade mark) bulbs are used, as on each occasion that a fresh supply bottle is slipped into the apparatus and used, the motor will receive fresh lubrication at the beginning of the run.
' ` `
: -~
. .
,,,lZ4,,,~ ~ .
.
, . ,,. ,.,,. ,. ...... , ~, . , . . , ~, . . ..... . .
- : - . . : ~ . -, , . , , .. :,::, ,, . - . :.: : .... .. :
S'7&~
The superheated gas, having first been throttled to a greater or lesser degree by the adjustable needle control valve 15, enters the chamber 23 via an inlet port 25, drives the vanQd rotor as it expands, and finally exhausts via port 26.
Prevention of escape of gas acxoss the faces of the vaned rotor may be achieved by the provision of two-face sealing discs 29, of relatively soft and low frictional material such as PTFE or oil-filled polyethylene, which are pressed against the faces of the vaned rotor by means of an'O' ring 30 or other compressible part such as a spring or spring-washer. The peripheries of the faces of ~he Rotor 22 preferably are provided with sli~htly raised rims (similar to the rims of coins~ which wear into ~he face sealing discs and so inhibit thP escape o~ gas across the faces of the vaned -rotor. The ' O' ring 30 also prevents escape of gas sideways from the pexiphery of the vaned rotor assembly ~where it meets the e~centric bore 23) and also ~eing ini~lally compressed, expands , , .
as wear occurs in the vaned rotor and face sealing discs s~ as to take up tha~ wear and prevent gas leakage pa~hs paths from d3veloping~ . -Higher ~o~or powers and greater eneryy stora~e for a given amount of working fluid an d buffer substance, and greater control and constanc~ of pxessure and motor power as the tank is~ emptied, is achievable by ~he al~erna~lve tank assembly shown in Figure 4. Th~s desi~n is of ~alue in the larger-power and longer-duration-power applicatlons such as lawn mowers, moped motors and light automotive motors, and in applica~ions requiring hlgher power-to-weight ' . ... ~.' , ' ' .'. '' . . : ~. ' . ' ' ' ' ., . .. '' , I ' ' '7~
ratios and lower gas consumption such as airborne power devices; it is described as follows:
A buffer substance 133 is held in a container 134 prefexa~ly of metal of high thermal conductivity and low weight such as aluminium alloy or magnesium alloy. The container, or a part thereof, has integ~al therewith an extension at one end which is in the form of a yoke 135. The yok~ 135 has on its inner surface a step 14~ and thQrefore has cylindrical por~ions 136 and 148 of narrower and wlder bore respec~ively. Inside the yoke 135 and preferably clos~ly-fitting with, and frictionally engaging, the portion 136 of narrower bore so as to provide good thermal communica~ion with the yoke.135 ~s a metal block 137 (or other form of thermal pick-up) which can be txansla~ed along the axis of the yoke 135 in to positions in which its.
outer surface makes greater or less physical contact with the innex surface of the yoke 135. By this means the surface area of the boundary across which heat may flow from the yoke l35 to the metal block 137 (which is preferably also of metal of high thermal c~nductivity) can vary from zero up to a maximum as the metal block moves leftward in Figure 4 Any radial clearanc~ between the metal block : - .
- ` 137 and the yoke 135 may advantageously be filled with a grease of high thermal cond~ctivity,(for example silicone grease having zinc oxide dispersed therein) in .
order~ to improve heat flow.
~he metal block acts as a bearing for one end of a rod . : of material of high thermal conductivity or a heat pipe 45Lwhis~exte~ aftward ~as shown? through a 1exibl~
dlaphragm 138 and a wall 147 integral with part of a tan~
:~13tj3LSi~7~
139, into the tank 139 itself. The ~iaphr~l has an inner marginal portion 1~9 held in enga~ement bet~veen the heat ~ipe or rod 140 and the meral block 137 and an outer marginal poxtion 150 held in engage~ent betvleen *he vall ) .. . . .
~ , ,<
. . .
: .
. .
. .
. ~ .
:. ~
. J
. :~ ' .
5'7~
i~7 ~ f~ard (~s SilO'.III) f~cc of an in\~arcl projecti~ll 151 ~lorn a hollo:v ~,~n~rally cylillc'ric~l cou~ r.l~G~oe~ in s~ threa~cd cnt,a~;er,ellt ~ith the tanl; 13~. Li.q~ icc:l ,.,~;, is aL~ilc to pass throut,:~ ~n a~erture in tllc wall 147 tl~rou~;h t;'nich the lleat pipe (or rod) 1~l0 e,;te~ds ~nd t:~erehy the clia~hr~ 138, in e~fect, acts ?~S a closure ol; wa:ll o~ t}~e tanl;.
The le:Et~iard end ( as sho~ ) OI the hcat pii,e ( or rod) 14d is supported in a line~r bearing 141 Iorr,lin~ part o~ a couplin~ ~eM'~er 11~) so that the heat pipe (or rod) may ~e translated l~ftward or ri~htward. A re~ion of that part of the heat pipe (or ro~) that is in the t~nl; 139 has a plurality of ~ins 145 ~ihich m~y be axial or r~ial as s~own in.~igure ~ aad ~lhich e~tend int~ the liquefied ~as in tlle tank 139. This aXr~n~emen~
facilitates flo~ o~ heat ~rom the he~t pipe (or rod) 140 into the tan~: 139.
Around the heat pipe 1~0 in the tank 139 is a co~pression sprinV 1~2 so arran~ed as to apply a leIt~Y~I~d Iorce on the heat pi~e asser.~bly, and scale~ so that when ~as pressure in the tan~ is at the desired level the metal block 13~ is approxirilately in the positio~ shown in Fi gure 4 .
The.yol;e 135 advanta~eously h~s an e~:ternial thread 143 whicl~ en,,ages a cor.lplementary i~ternal threiad of the couplin~, member 14~. The coupling ~.ernber 1~ is pre~erably o~ therr.l~lly~ sulatin~ r~1aterial such as ~lass-reinIorcecl uylon so ~s to prevent undesirable flow o~ heat ~rom the contain~x 134 to the t~2llr 139.
.. . .
~l 22 -~.~.. ~ . . . .... .
'' ' .' ;; ' ' '' ' ' ' :~ , . : . : , , ' 7~
The engaging threads between the coupling member 144 and the yoke 135 allow the yoke 135 to be adjusted so as to provide greater or lesser thermal coupling between the inner surface of the yoke 135 and the metal block 137. This allows external adjustment of the controlled gas pressure in the tank 139 and thus of the power of a motor which can be connected to the let hand end (as shown) of the coupling member 116 in a manner ~imilar to that shown in Figure 1.
The function of the tank assembly shown in Figure in stabilising gas pressure will now be apparent as follows:
Any withdrawal of gas from the tank 139 will initially cause a slight fall in both the temperature and the pressure of the contained gas, and thus a fall in temperature of the left hand end of the heat pipe or metallic rod 140. The control spring 142, because of the said fall in tank pressure, will thus cause the heat pipe assembly to moveleftward, increasing the thermal contact area between the metal block 137 and the yoke 135 which, being warmer than the now-cooling heat pipe assembly, will convey more heat into the heat pipe or metallic rod and thence via the fins 145 into the liquid gas, thus restoring and regulating its temperature and pressure and causing the diaphragm 138 to flex outwardly and return the heat pipe (or rod) rightwards (as shown).
An equal or greater advantage of this design of tank assembly is its ability to control the heat flow from a much larger store of heat. Thus, even if the buffer substance 133 is much hotter than the tank 139 and its contained liquid gas, heat flow into the liquefied gas. . . . . . . . . . . . . . .
,~
, . . . ~ . . . , , j ~ . . :
will be regulated so as to maintain the desired gas pressure and not allow it to rise undesirably and cause a wasteful increase in gas consumption. The buffer siubstance may therefore be heated above ambient temperature before use, so as to store a greater amount oE heat energy which, during later use, is transferred to the working fluid and converted ; to useful energy in the motor.
In addition, the arrangement allows the generation of gas pressures much higher than would be achieved at ambient temperature and, provided that the motor has an adequate expansion ratio, this permits a marked reduction in gas consump-tion for a given power output, or a large increase in power output at the same gas flow.
To permit these greater amounts of heat storage it is desirable to pre-heat the buffer substance before use and this may be accomplished for instance by either an electric element or an electrical heating jacket 156 preferably fitted with a thermostatic cut-out. If intended as auxiliary power to an I.C. engine, the buffer container may be kept hot by means of the hot exhaust or other engine heat (eg the cylinder block). In all such cases it is usually desirable to thermally-insulate the tank and buffer container so that the stored heat does not leak away to the environment. Referring ,~ to Figure 5, a disposable supply bottle or bulb 201 containing C2 i~shown partly emptied) and painted on its outside surface with a thermally-conducting paint has a small oil-soaked `' pad 2Q2 positioned immediately on the inside of a closure diaphragm 203. The supply bulb 201 is shown inserted in a holder 204 which is advantageously made of injection-moulded glass-reinforced nylon and which is . . . . . . . . . . . . . . . . .
i ~ .
:
, , ~ ; , , , ;
6~57~3 provided with a lining 205 of metallic foam or mesh containing a first buffer substance 206 if the bulb contains ~g o~ CO2, preferably which comprises approximately 2 grams of water.
The le~ward end (as shown) of the holder 204 is provided with a female thread which engages with the male thread of a body member 207, and this thread not only supports the holder 204 but also allows the closure diaphragm 203 to be punctured by a hollow piercing needle 208 when it is desired to energize the apparatus by increasing the engagement o~ the threads.
The holder 20~ is sealed against loss of the first buffer sub-stance 206 by means of an '0' ring 209 and the neck of the supply bulb 201 is sealed against leakage of the CO2 after puncturing by means of an '0' ring 210 about the neck of the bulb 201. The piercing needle 208 is held in the body member 207 by means of a nut 211 and sealed by an '0' ring 212 and soldered to a tube 213 which is coiled within a superheater chamber 214 and which terminates with a soldered connection-to a probe 215.
The superheater chamber 214 in this embodiment is housed between an end member 229 and the lefthand end face (as shown) of the body member 207O In this embodiment it may contain 1.5 grams of 99% glacial acetic acid/1%/water (by volume) which comprises a second buffer 216 and ~hich assists the superheating process to - a vapour temperature of approximately 10C. A coil ratainer 217 in the form of a disc of plastic sheet (such as "Cobex" R T M P~C
sheetl serves to contain the coils of the tube 213. The probe 215 is provided with '~' ring 218 and is pressed . . . . . . . . . .
. ~ ~
, :
:'1 ' ~ ~
into a housing 219 after the application of an adhesive sealant such as that sold under the trade mark "Loctite". The probe housing 219 is itself pressed and sealed into the end member 229 either using "Loctite" or possi~ly by moulding it into the end member 229 which, together with the body member 207, may advantageously be injection moulded in glass-reinforced nylon or acetal resin or similar plastics resistant to acetic acid. The superheater chamber may be sealed against loss of the second buffer 216 by means of an '0' ring 220 or alternatively sealed to the body member 207 by an adhesive sealant or by spin or friction welding. All metallic parts in contact with the second buffer 216 are desirably made of aluminium or stainless steel or ~; electro-plated mild steel when acetic acid is used; copper and copper containing metals such as brass are likely to corrode and are not therefore recommended.
- Referring to Fig 6 and Fig 7 it will be seen that the motor is provided with a mounting flange 221 and mounting screws 222. The adaptor shown in Fig 6 is so designed to marry with this mounting flange 221 and is provided with tapped attach-20 ment holes 223 positioned so as to accept the mounting screws 222 as indicated by the dashed lines, and thereby to allow the adaptor to be fixed to the motor. The leftward end (as shown~ oE the adaptor is provided with a socket 224 sized to take an inlet feed ; pipe 225 of the motor by means of a soldered connexion. The right-ward end (as ~hown) of the adaptor is provided firstly with a male - thread 226 which engages with a female thread in the leftward end , . , -' (as shown) of the housing 219 shown in Fig 5 so as to allo~ the motor plus adaptor to be . . . . . . . . . . . . . . . . . . . .
' "' ''" ' '" . '' " '' '; '' ` ' ~ '~ ';' " '' ."''' '' '' ' , ' "'.;'', ' " '~''' .' "." ' ''' ' '' ' " "" '' `'. ' "' ' , . ' . ' " ' " " ' ~ .' ~ "'-' . .'. ' ' ' , ' .' . ' . '' '. . '.' " ' ' ' ' ' ' "' " ' ' " ' ' ' ' " : ' ' .,:,'., ., . . , . ', ' ,. , ',' . ' ,',. ' . ' ,' ' ;'', . '': ' '.' ~ ,', ' " ' ." " ' ". ' ." ' ' " ' " ' , . .: - ' ' , . , ' . ,. . " " ' ,', , , , , '. ' ' ' ' ' . ' ~ ' ' '' ' ' , ' ' ~ ' ', ' :
s~
quickly attached to the probe, and secondly with a chamfered socket 227 which is designed so as to accept the probe 215 and at the same to compress and seal the '0' riny 218 o~ the end member in Fig 5.
The oil-soaked porous pad 202 enables the issuing gas from the supply bulb 201 to carry with it droplets of oil into the motor. This technique is particularly useful where disposable supply bottles such as "Sparklets" (trade mark) bulbs are used, as on each occasion that a fresh supply bottle is slipped into the apparatus and used, the motor will receive fresh lubrication at the beginning of the run.
' ` `
Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A motor having in combination there with apparatus for supplying to the motor gas evaporated from liquefied gas, said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas evaporating from the liquefied gas is conducted into the motor, and in heat con-ductive relationship with the vessel, at least one con-tainer holding a buffer substance which during operation of the motor releases heat to the vessel and the liquefied gas therein, whereby the tendency of the evaporation of the liquefied gas to cool the remaining liquefied gas in the vessel is at least partly counteracted.
2. A motor according to Claim 1, in which the buffer substance is contained in a jacket surrounding the vessel.
3. A motor according to Claim 1, in which the said container is located in the vessel.
4. A motor according to Claim 1, in which the vessel has associated therewith means for pre-heating the substance.
5. A motor according to Claim 1, additionally including manually operable means for placing the passage in com-munication within the vessel.
6. A motor according to Claim 1, in which the buffer substance is a liquid which freezes at a temperature between ambient temperature and the final operating temperature of the liquefied gas.
7. A motor according to Claim 1, in which the passage has means for causing the evaporated gas to undergo a pressure drop of more than 10% of the saturation pressure of the liquefied gas at the prevailing temperature of the liquefied gas in the vessel, whereby the speed of the motor is able to be stabilised.
8. A motor according to Claim 7, in which there is at least one secondary container holding buffer substance in heat conductive relationship with at least part of the said passage.
9. A motor according to Claim 8, in which the buffer substance in the said secondary container is a liquid which on freezing releases heat to evaporated gas flowing through the passage, and which has a freezing point between ambient temperature and the temperature of the evaporated gas entering the passage, and in which the buffer substance in the said container in heat conductive relationship with the vessel is a liquid which on freezing releases heat and which has a freezing point between ambient temperature and the temperature of the liquefied gas in the vessel, the buffer substance in the secondary container having a freezing point greater that the freezing point of the buffer substance in the said container in heat conductive relationship with the vessel.
10. A motor having in combination therewith apparatus for supplying to the motor gas evaporated from liquefied gas, said apparatus comprising a vessel containing liquefied gas, a passage which affords communication between the vessel and the motor whereby gas evaporating from the liquefied gas is conducted into the motor, and, in heat conductive relationship with at least part of the passage, at least one container holding a buffer substance which during operation of the motor release heat to evaporated gas as such gas passes through the passage, thereby raising the temperature of said evaporated gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA282,043A CA1061578A (en) | 1977-07-05 | 1977-07-05 | Stored energy motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA282,043A CA1061578A (en) | 1977-07-05 | 1977-07-05 | Stored energy motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061578A true CA1061578A (en) | 1979-09-04 |
Family
ID=4109064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA282,043A Expired CA1061578A (en) | 1977-07-05 | 1977-07-05 | Stored energy motor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1061578A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012001368A1 (en) | 2010-07-02 | 2012-01-05 | Linde Aktiengesellschaft | Gas storage apparatus |
| CN116518583A (en) * | 2023-04-20 | 2023-08-01 | 国网江苏省电力有限公司常州供电分公司 | Energy storage system for drying liquid compressed carbon dioxide by circulating coupling heat pump |
-
1977
- 1977-07-05 CA CA282,043A patent/CA1061578A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012001368A1 (en) | 2010-07-02 | 2012-01-05 | Linde Aktiengesellschaft | Gas storage apparatus |
| US8579146B2 (en) | 2010-07-02 | 2013-11-12 | Linde Aktiengesellschaft | Gas storage apparatus |
| CN116518583A (en) * | 2023-04-20 | 2023-08-01 | 国网江苏省电力有限公司常州供电分公司 | Energy storage system for drying liquid compressed carbon dioxide by circulating coupling heat pump |
| CN116518583B (en) * | 2023-04-20 | 2025-05-06 | 国网江苏省电力有限公司常州供电分公司 | Energy storage system of liquid compressed carbon dioxide cycle coupled with heat pump drying |
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