CA2135609A1 - Piston and cylinder devices - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to piston-and-cylinder devices having an output member adapted to drive vehicles, generators or other mechanical arrangements. The device may in its simplest form comprise a cylinder including a chamber at least one piston having an exterior cylindrical surface, and which is adapted to partake of a motion having a component of movement lengthwise of the cylinder and a rotatable output member. There are also provided cam means comprising a first cam part and a second cam part, one of said cam parts being a cam track arrangement formed for example in the piston surface and the other being a cam follower means formed on the inside surface of the cylinder and adapted to engage said track arrangement, the construction and operation being such that said cam means operates to impart to the motion of the piston a rotational component of movement and such that rotary motion produced in the output member is derived from said rotary component of movement of the piston motion. Conveniently, a skirt flange may be provided on the piston to act as a sleeve valve.

Description

p~ Y~ ~ UU ~J4 -'t~ .fU~Y

PISTON AND CYLINDER DEVICES
The invention relates to piston-and-cylinder devices, particularly but not exclusively to devices having an output member adapted to provide drive or propulsion to vehicles, generators or other mechanical arrangements.
The invention provides a piston and cylinder device comprising a cylinder, said cylinder including a chamber at least partially defined by an interior surface of said cylinder, at least two pistons each having an exterior cylindrical surface, and an at lea~k substantially radially extending end surface, each said piston present in the chamber being adapted to partake of a rotational motion having a component of movement lengthwise of the cylinder, and an output member adapted to rotate about a lengthwise extending axis thereof, wherein there are provided cam means comprising a first cam part and a second cam part, one of said cam parts being a cam track arrangement formed in one of said surfaces and the other of said cam parts being a cam follower means formed on the other one of said surfaces and adapted to engage said track arrangement, the construction and operation being such that said cam means operates to impart to the motion of ~he piston a rotational component of movement and such that rotary motion produced in the output member is .
derived from said rotary component of movemsnt of the piston motion. ~ `
Advantageously, the motion of the piston may be ;~ ~ -initiated and malnta.ined by a source of chemical or STl~ S~l~

wo93/2365g ~13 ~o9 PCT/~ B93/OU904 elect~ical energy. Prefera~ly, the ca~ trac~ arrangem~nt may be a sinusoidal cam trac~ formed in the exterior surfac~ of the piston and the c:am follower means may c~mprise at least one cam follower projecting from the intPrior sur~ace o~ the cylinder cham~er.
Conveniently, ~here may be provided two lobes in the sinusoidal path o~ the cam-~rac:~. However, in many applications of the devices according to the present invention, three or more lobes may b~ found satis~actory or even prefera~le.
Conveniently, the source of energy may be a liquid fuel of various kinds, petrol, alcohol and other high- or low-actane fuels or may be electric or any other suitable sour~P. In some instances of use tur~ine or other propeller-type blades may be powered which in turn permit by-pass air to be used possibly in the ~anner of an airc-aft-type engine, with additional fuel injection to provide an arrange~en~ similar to that of an after-~ur~2r.
In some of ~he examples to be described below, two or more pistons may be ar_anged in tandem wit~in a single ::
cylinder chamber, said cham~er being divided by the . ;
pistons into a plural~ty of sub-cham~ers. AdvantageoUsly, each sub-chamber may be provided with a spar~ plug or other suitable ignit~on device for a fuel/air mix~ure delivered to the suh-c.hamDers so as to operate in a pre-determined two- or four- stroke cycle. ' -~
Acc~rdiny to the lay-out of the device, the oUtDUt ~ `

;'`' ;; '""`' -`'i; . ~.,o~

wo a3~236~s 213 ~ ~ 0 9 PCT/~B93/00904 member may be arranged to pass axially through ~he piston in a manner ensuring the rotal:ion of ~he output member with the rotary component of mo~ement of the piston motion but compensat~ng for or preventing axial ~ovement with the lengthwise component thereof.
The i~vention also provid~3s in another of its several features a piston-and-c~linder device as described in ~he sacond paraaraph of the present specification wherei~ said piston or pistons are provided with a cir~lar or annular end sur_ace adapted to receive an impulse intended to ~ove the pis~on in the cylinder cham~er, said end surface being provided with radially extending ~luted portions comDrising an array of surfacP portions arranged obliquely with respec~ to a radial plane of the plston.
Further features and ad~antages of devicss ac~ording to the invention will become apparent from the following detailed descripsion of a plurality sf em~odLments of the invention. It will be unders~ood that the description, which is to be read with reference to the drawings, is given by way of example only and not by way of limitation.
In the drawings~
Figure 1 is a~schematic, view in longitudinal $ection ~ -of a first device acc-ordi~g to the in~ention includ~ny one piston; . `
Figure 2 is a si~ilar view to that of Figure 1 showing :~
the pis.on of the first devicP at a different stage in a . ~ :

two-stro~e cycle of opera~ion; ~-.-:.,-~

W093/236~; 2 ~ PCT/GB93/009 Figure 3 shows a ~odification of ~he ~irst deYic~;
Figures 4 & 5 are sche~atic ~iews in longitudinal sec_ion of a second device comprising two pistons in different stages of operation of the d~Yica;
~ igures 6 & 7 are views, si.milar to Figures 3 and 4, of a third device comprising three pistons;
Figures 8 & 9 are views of a fourth deYice incorporatin~ a lubricant-circulating arrangement;
Figure 10 is a cross-sectional view on line X-X o~ ~
Figure 9; .
Figure 11 is a frag~entary view cf a vaned shaft of the four~h device;
Figure 12 is a perspec~ive view vf a piston showing an array of fluted portions an an end surface thereo~
Figures 13 & 14 are schematic representations of a water and an air-cooled jac~et arrangement respectiYely;
Figures lS & 16 shows the layouts of two exhaust manifold ar~angements suitable for use with devices according to the invent_on;.
Figures 17 & 18 show lengthwise and transverse views ~
respect-~ely, through auxiliary equipment; .~ . .
Figures 19 & 20 show alternative forms of ~alve -.. - .
arrangements; ~ .

: Figure 21 shows a perspective view of a ~adified piston arrangemen~

. Figures 22 & 23 are views similar to those of Figures 8 and 9 showing a further device incorporating the t ~"',""'.

~. -2 :13 .j 6 ~ ~ Pcr/cBg3/oo9o~

modif_ed piston arrangemen~ in Figure 21: and FiourP 24 illus~-at s a power boos~ devic~ capable of auo~en~_ng the overall engime ou.?uL.
The firs~ devic~, illus~r2l~ d in Figures 1 and 2 of the drawings, compr~ S25 a hollo-~ cylinder 2 one end wall 4 of which is provided wi~h an ape~ ~r_ having bearings 6 ~rouch which projec s an ou~u~ shaf~ 8 sliding received in an axi~l slot 10 of a flywneel 12. Relative rotary movement between the shaft 8 and the f'ywheel 12 is preven~ed by keying splines (nol shown3. Recei~ed within :~.
a chamDer 14 or ~e cIlinder 2 is a pis,on 1~ to which an inner end portian of the shaf~ a is ccnnec_sd. The piston has an extPxlor cylindrical sur acq 18 in which is formed a cam trac~ 20 providing a s~nusoidal path and having two lo~es.
A compression sealing ring ~2 is provided in an ~-annular groove around ~e piston 16 in ~Ihe region of an opposit? end face to that c~nne~2d t~ the shaf~ 8, the`.
ring ac_ing also as a sc-aper devics against a portion of an int~rior surface 24 of the c~linder from whic~ projec~
two cam followers ~6. The c~m followers 26 may be in the ~orm of studs or bossesi or c~limdr~c-~1 roller mem4ers as shown.: Suc~ rollers will re~uire a substantialIy rec=an~ular cross-sec-ion cam ~-~c;v but a domed stud or boss may be used wi~h a U-sna?ed trac.Y. r As viewed in Fi¢ures 1 and ~, there is provided at the left-hand end port~on or t~e c;~amDer 1g, a sparX plug 28 ' ~ W093/2365~ 2 ~ ~ ~3~9~ PCTtG893/00~04 ~ ., and an injection nozzle 30 for the proyi-cion of a fuel/oil mixture arranged to opera~e a two-stroke intPrnal com~us~ion cycle. Figure 1 shows the position of ~he piston 16 as the plug 28 spar~:s to ignite the fuel del~vered by the nozzle 30. As the piston is impell~d to ~hP right, the action o~ the c:am ~ollowers 26 in the trac~
20 causes the piston to partake of a motion having not cnly a lengthwise co~ponent of ~ovement but also a rotary component. The extent o~ lengthwise movement is limited by the throw of the cam trac~ which guides movement ~etween the positlon of the piston shown in Figure l and the position shown in Figure 2. In the Figure 2 position, :
the piston has ~oYed so as to unco~er exhaust ports 32 formed in the cylinder 2. ~ :~
It will thus be apprecia~ed that the piston motion comprises a rotational movemen~ ~f 180- for each operation of the spar~ plug 28 and includes a shor~ lenqthwise moYemen~. The output shaft 8 thus partakes of a.similar short t-avel motion. HoweYer the shaft 8 is s~lined into the axial slot 10 for sliding mo~ement an~ therefore only f, the ro~ational component of movement is transmitt~d to the flywheel. It will be found that the operation of the device is appreciably smoother than that of other known operat_onal sinqle~ linder motors. Although Figures 1 ~-:
and 2 illustra~e a cam trac~ having a two-lo~ed sinusoidal curve, it wi.ll be un~ers~ooà tha~ a single lobe configuration may be used as shown in Figure 3, in which ~ 3~ 9 ~15 JUlY 1g94 ~, similar par~s have been allocated similar reference numerals to those used in Figures 1 and 2. In this modification, only one cam follower 26 is necessary and it will be observed that the lengtklwise movement is greater than that required by the arrangement shown in Figures 1 and 2. It will be understood that in ~any examples advantage may be taken of the ability to use a wide but shallow piston with a cam-track having ~hree or mor~ lobes to provide an exceptionally rapid rate of strokes of the piston.
In all cases, suitable water-cooling, or air-cooling jackets or other devices will b~ required, together with ~xhaust gas removal passages, but these are omitted in Figures 1-3 for the sake of clarity. ` ~
In Figures 4 and 5, a second embodiment of the; ~ .
inYention is illustrated which is similar to that shown in Figures 1 and 2 in many respects, ~ut differs in that a single spark plug, 3~, and a single fuel injection nozzle 36 is positioned at an intermediate region of an elongate cylinder 38 in which are received t~o pistons 40,40', each having a t~o-lobe sinusoidal cam track 42 engaged by two cam-~ollowers 44. Thus the two pistons are arranged to hare a common combustion sub-~hamber. The piston 40 iS
provided with a shaft 46 which is received in an axial slot 48 formed in the piston 40'. The shaft 46 is ~
provided wi~h keying members 50 which engage in grooves of :.
the slot 48 to permit lengthwise relative movement but , Sl~18Sr1 W093~2365~ ~ ~ 3 ~3 ~ Q 9 PCT/CB93/00904 ~3 -prevent rotational r~lati~e ~ovement between the two pistons. It will be observed that at the time when the spar~ plug 34 opera~es, the keying members 50 are shielded from possi~le damaqe from fue]L ignition by being fully received within the slot 48.
The piston 40' has an output shaft 52 secured thereto in a manner similar t~ th~ mounting af the shaft 6 of Figures 1 and 2, with a similar arrangement of the sha~t : ~
and a flywheel 54, corresponding to the flywheel 12. ;~ ~;
Thus, when the spar~ plug 34 operates to cause .
ignition of the fuel/air mixture from ~he nozzle 36, the pistons move apart from each other but as they do so, they .~ -rotate simultaneously in the same sense. The rotation of the piston 40 thererore assists the rotation of the piston 40' through the shaft 46 and more power is thus available at the output.
Figures 6 and 7 illustrate a third em~odiment in which an extended arrangement is shown which avoids any disadvanta~es which may be encountered under certain circums~ances connectea wi~h ~h~ ~ounting of ~he output shaft when the latter is allowed lenqthwise movement with respec- to the cylinaer and the flywheel.
In this embodimenl, a cylinder 56 provides four ; combustion regions or sub-cham~ers, ~, B, C and D, of a chamber 58, in which are received three pistons 60, 62, 64, eacn provided with a sinusoidal cam tracX ~6 engaged by cam folLowers 68, formed and arranged in a manner W0~!3/~65 213 3~9 PCr/GB93/00904 _g _ , :

similar to that desc~ibed above. The pis~ons are, however, pro~ided ~ith axial p~ssages and are mounted for mo~ement length~ise on a throuch shaf_ 70 jou~nalled in :~:
gas-~ight beari~qs 72 and 74 at end walls of the cylinder S6, the right hand end of the shar ~ 70 as viewed in khe Flyure being connec-ed wi~h a flvwhe~l 76 in a ~.:
c~nvent onal ~anner. Relative r-~at~onal mo~ement between the pistons and the shaf~ 70 is however preYented by ~he prc~ision on the shaf~ 70 of ke~ing mem~ers 78 which slide with resDect to grooves 80 for~ed ~it~in the axial passaqe o~ each piston.
The operation of ~he thir~ em~odiment is as follows.
With the pistons 60, 62 and 64 in the positions shown in Figure 6, spar~ plu~s ~2 in su~-chamDers B and D operate to ignite a fuel~ai- ~ixt'-r2 inlected from assoc~ated ones of nozzles 84. The pistons 60 and 64 therefore move in a le~tward direction and pis.on 62 moves to the right, all three pistons rotatlno t~.-ouch 90- as they move lengt~wise with the cylinder. When the~ have reached the positions shown in Figure 7, the pis.ons 60 and 64 are then mo~ed .
towaràs the Fiqura 6 acain bv the operation of the spar~
plugs 82 in s~b-chamDers~A and C ~o ignit a ~uel/air ~ ;
~mixture in~ected by the ap-roDr ale noz_les 84.
The rotational movemen, or .~e pis.ons is t.~us t-~nsfer-ed to the ou~t shaf' ,0, wi~ the aZYan~age ~that eac~ s~ro~e of ~he pis~^ns is a power st~o~e, thus --~
enaDlinc con~iderable ou;~u~ .o be achieved. Moreover, it W093~'365; PCT/GB93/00904 2 ~ 9 --10-- .

has been fou~d that the pre~encP of the shaft in a cen~ral position in each com~ustion sub-chamber has an ad~antageous effect on the dis~r~bution of the fuel as it .
is in j ec~ed, due to the d~flecting act~on of the shaft on the injected stream which disperses the fuel more eYenly throughout the availa~le space, the ensuing ignition explosion i~pinging upon the end surf c~ of the piston in a more even manner than is conventional in internal comDustion engines.
Figures 8, 9 and lO illustrate a fourth em~odiment of the in~ention which inc'udes a cylinder 86 in which are recPived two pistons 88 and 9O ~ount~d for movemeni upon an out?ut shaft 92 journalled in gas-tight bearings 9~, 96 in end walls of the cilinder 86. The operation of the pist~ns 88, 90 and spar~ plugs 98 and associated inject~on nozz7es 100 is similar to that desc_ibed above, the pistons moving in a reciprocating motion on the shaft 92, ~he motion having co~ponents of axial and of rotational movement~ Outward and inward stro~es are powered, sincs there is provided a plug 98 and fuel inlet lOO in each of the three com~ustion chambers. The construction of the -~ ~
pistons 88 and 90 wil' however be described, with ~:
reference to a convenient lubrica~ion system, enabling a separate oil supply _ather than the additlon of oil to the fuel as in a two-s~roke cycle.
Each piston 88, so ccmprises a main body por~ion l02 and t-~o end plates 10~ in sc-P~-~hre~ded engagement with ~093/236;5 ~ PCT/CB93/00~04 f~ v ;

the body portion. Oil seals ~06 are proYided in addition to piston rings 108. Further oil seals llO are provided in annular bloc~s 112 which ~or~ end faces of a hollow ~-cham~er E within the piston. Cam-tracXs 114 are provided in the bloc~s 112, and are engaged in a manner similar to ~hat descr~bed above by cam ~ollowers 116. Pro~ecting inwardly of the cham~er E from the bloc~ 102 axe ~wo pairs of flanges 118; between the flanges of each pair is rereived one of two vanes 120 projecting from the shaft 92. Shaf! 92 is hollow for most of its illus~rated length and provides a cont-ally arranged passage 122 for the supDly of oil from an oil feed 124. Orifices 126 allow the oil to pass into the chamber E and thence through rest-~cted orifices 126 to ~h~ cam trac~ 114 to lubricate the piston movement. A spiral groove 128 is provided in -the interior wall of the cylinder 86 to carry~ away the cil ~.
from the cam trac~ 114 and the exterior surface portion of ~:~
the piston between the seals, in order to allow its return to an external sump by means of a vacuum pump (not shown), for re-use at oil feed 124. .--On each outer face of the end plates 104 there is provided an array of ~adially extending fluted portions. -~
130 (Figure 12) arranged at an o~lique angle to a radial . ~
plane of the cylinder 86, with intervéning surface 132 -.
each lying in an axial plane. The advantage of suc~ a -;
layout is that the ignition explosion impinges on the surfaces 130 at an ancle and this ac~s to enhance the :

w~93t~36~ PCT/GB93/00904 -2~ ~r.~Q~ ..
;..~ ~ ."
~12-desire rotational motion.
~ ith respect to the cooling of the devices illustrated, the cylinders may be received within a wa~Pr cooled jac~et 134 as shown in Figure 13 or an air-cooled jac~et 136 as shown in Figure 14. In arrangements including air~cooled outer jac~ets, it is en~isaged that a fan or tur~ine blade arrangeml~nt 133 ~ay be provided to drive air through the annular space between the jac~e~ and the cylinder in the direction indicated by arrows F.
A second fan 140 may a}so be provided to assist in pulling air through the space.
~ he space between the jac~et and the cylinder may also be used, with suitable ducting, to accommodate and remove exhaust gases from exhaust ports 32, 32'shown in the various Figurés. In the examples these ports have b~en usually illustrated for the sake ~f s~mplicity as ports without valves, the ports being covered and uncovered as the pistons ~ove. Figures lS and 16 show cross-sectional views of exhaust arrangements including three-port and .
two-por-~ lay-~uts respectively, acc~rding to the required gas-flow charac~eristics. The Figures illustrate a cylinder 142 having a shaft 144 passing through its piston(s) with ports 146 leading to exhaust manifold arranqemen~s 148 via annular space 150 between the cylinder 142 and a jac~et 152. Fuel/air inlet positions are also indicated at 154.
Figur2 11 shows a side elevation of an arrangement W~3/~36~ 3 '~ ~ Q ~ PCT/GB93~009M
..

lllust~ating a lay-out using ~he example shown in Figur~ 8 and 9, but provided with the re~ui_2d auxilia~
esui~men~. For the sake of si~ c~ty the details of the pis.on-and-cylinder devic is indica~d by the area F.
Although an ai--cooled arrang~ment may be found sat.sfac~ory, Figure 17 shows a watar pumD 156 taking coolant from a watPr jac~et lS~ t2 a radiator G (not shown). An exhaust impeller 16~ driYer from the device F, takes exhaust gas fr~m an exhaust manifold 162 to exhaust and an induction impel7 er 164 pressurises the ~uel/air mix*ure in an inauc~_on ~anifold 166. An ;~
alternator and c~n~-ol gear ar-~ngement 168 is mounted on an auxlliary shaft 170. It will ~e understood that ecuipmen~ requiring power may bP mou~tad, not directly on its shart but may ope~te thrcug;~ gearing or clutch ;;
devices as nec~ssary. :
Because cf lay-~ul problems which would arise pa--ic~larly with the use of m~lt ple ent~y and exhaust -;.
.. ~ .
pa F s to impro~e comDus~ion, the use of specialised valve de~ices will be advanta~eous. - :~
suc;~ a valYe devica is shown in Fioures 18 and 19.
Refer~ing ts Fi5uro 19 j an elec~ -omagnet 172 is provided with a contral aDe - ~re '74 througn which passes a stem 176 of a valve 178. The stem 1J6 is set in sliding bear_~as 180 tFigure l~) in t~e manifold body. The outer end of ~he valve com~ri ses a coilar 182, with a comDression spring 184 received ~e~een t~e ccllar and the ~ n ~ JULY t9~4 magnet 172. Energisation of the magnPt will attract ~he collar 182 and compress the spring, which will act as a return spring to force the valve to return to its original position when the magnet is de-energised. Figure 18 shows an arrangement of two tangentially offset flow inlet/outlets from the manifold 166 and illustrates one valve 178 in an energised state and one in its de-energised state. The ~nergisation of the magnet 172 is controlled by a suitable electronic sequencing device, directing current to the valves in the required seguence, its power being ini~ially deriYed from a battery (not shown) and ~hereafter from ~he alternator 168. Control of the sequencing rate would be also derived from the .
throttle action on the fuel/air supply (carburettor).
An alternative form of valve is shown in Figure 20, in which a small linear motor 186 surrounds the valve stem 176, which then becomes the armature of the motor. A
frequency converter or frequency generator (not shown) will also ~e provided in the arrangement since ~he linear motor speed normally depends on the frequency of an alternating current. The ~requency converter thus operates upon the sequencer and thence the valves 178.
Yet`another alternative arrangement is illustrated in Figures 21 to 23 in which end face 188 of the pistons is provided with a cylindrical flange 190 extending axi lly there~rom in the form of a skirt. The flanges are pro~ided with apertures 192 which are arranged to co-incide with apert~res in the wall of the cylinder (for example, cylinder 86 in Figure 10) at a stage in the ~1 S~BS~

. W.~93/~36~ 7,13 S & B 9 PCT/GB93/00904 .~ . .

c~cle. Since there is a ~uel/air mixture present in the cylinder openings under conditions o~ increased pressure and the exhaust syst~m is under reduced pressure (evacuatlon~ the s~ir~-like flange 190 will be seen to .
operate in the manner of a sleev~ valve with no moYing parts other than the pisto~ itself. This is illustratPd in F~gures 22 and 23 in which parts shown which are -:~
similar to those illustrated in F1gures 8 and g are given similar reference numerals provided with a suffix, for example spar~ plugs 98'. The se ence of operations is ~;--~.
similar ~o that descr~bed in relation to Figures 8 and 9.
~owever, in Figures 22 and 23, the pistons 88', 90' are :
proYided with the above mentioned skirt-like flanges lgO.
Al~hough the aperture 192 will vary in shape and position ::
acc_rding to the layout of the piston-and-cylinder arrangement, the presen~ layout includes operations whic~
when for example the middle spark plug operates, (Figure 22) are positioned to allow the spar~ to ignite the fuel/air mixture and, as shown ln Figure 23, then to allo~
passace for ~he exhaust gases ~hrough ports 32'. It will be observed that the pOF~S 32~ are valveless since the flanges 190 act as sleeves in a sle~ve valve. Thus the ~nly moving parts in the arrangement ar the shaf~ and :~
pistons.
A further embodiment of the invention is suitably ~ -employed in an arrangement capa~}e of providing a shor_-ter~ i~pulse or boost to the piston engine, in a ~, W093~2365; 7 ~ '~ J609 PCT/~B93/00904 ., similar manner to that in which a jet engine is provided with "after-b~rn" capabilities. Figure 24 shows an example of such a boos~ arrangement in the context of the present disclosure.
~ n engine 194 constructad as before described is arranged to dri~e a compres~or/fan arrangement 196,198, one at aach o~ the front and rear ends of the engine body. The fans drive a large quantity of air through an annular space 200 between the engine cylinder and the outPr jac~et 202. The engine is cooled by this air ~low which air is compressed by the fans and the cont~uring of the jac~et housing rearwardly of the second fan 198 around a con~oured flow control body 204.
The compressed air now enters an annular com~ustion chamber 206 to which is supplied fuel (without air admixture) in the form of fine droplet~ from an array of spray jets 208. The hot gasses from ignition at this stage pass throu~h a t~r~ine 210 which is linked to the engine 194 and so assists its power output. The exhaust gases also con~ribute a measure of thrust so enhancing the overall power output. The arrangement will also be providqd conventionally with sta~or blades 212 as well as tur~ine blades. The sta~or ~lades are mounted in association with a fur~her contoured ~ody portion 214, which i~ appropriata may be mo~able axially of the exhaust outlet 216 to assist in the control of exhaust gas ;. ~

WO 93!~36~ 9 PCT/GB93/00904 - 17- ;

pr~ssure and velocity.
Various modific:~t~ons may be made wit~in the sc~pe of t.'le inven~i=n as deflned in the fol' owing claims.

' ,~

Claims (20)

-1?-CLAIMS:

1. A piston and cylinder device comprising a cylinder, said cylinder including a chamber at least partially defined by an interior surface of said cylinder, at least two pistons each having an exterior cylindrical surface, and an at least substantially radially extending end surface, each said piston present in the chamber being adapted to partake of a rotational motion having a component of movement lengthwise of the cylinder, and an output member adapted to rotate about a lengthwise extending axis thereof, wherein there are provided cam means comprising a first cam part and a second cam part, one of said cam parts being a cam track arrangement formed in one of said surfaces and the other of said cam parts being a cam follower means formed on the other one of said surfaces and adapted to engage said track arrangement, the construction and operation being such that said cam means operates to impart to the motion of the piston a rotational component of movement and such that rotary motion produced in the output member is derived from said rotary component of movement of the piston motion.

2. A device as claimed in claim 1 wherein the cam track arrangement is a sinusoidal cam track formed in an exterior surface of the piston and the cam follower means comprise at least one cam follower projecting from the interior surface of the chamber.

3. A device as claimed in claim 2, wherein the cam followers are studs or roller devices.

4. A device as claimed in claim 2, wherein the cam track has two lobes.

5. A device as claimed in claim 2, wherein the cam track has three lobes.

6. A device as claimed in any of the previous claims, wherein two or more pistons are arranged in tandem within a single cylinder chamber, said chamber being divided by the pistons into a plurality of sub-chambers.

7. A device as claimed in claim 6, wherein each sub-chamber is provided with an ignition means so as to operate in a predetermined two- or four-stroke cycle.

8. A device as claimed in claim 1, wherein the output member is arranged to pass axially through the piston to ensure rotation of said output member with the rotary component of movement of the piston movement, axial movemens of the output member with the lengthwise component of the piston member movement being minimized or prevented.

9. A device as claimed in any one of the preceding claims, wherein the motion of the piston(s) is initiated and maintained by a source of chemical or electrical energy.

10. A device as claimed in claim g, wherein the source of energy is a liquid fuel.

11. A device as claimed in claim 1, wherein said piston or pistons are provided with a circular or annular end surface adapted to receive an impulse intended to move the piston in the cylinder chamber, said end surface being provided with radially extending fluted portions comprising an array of surface portions arranged obliquely with respect to a radial plane of the piston.

12. A device as claimed in either one or claims 1 and 11, wherein the output member co-operates and drives a flywheel arrangement.

13. A device as claimed in any one of the preceding claims, wherein there are provided two pistons sharing a common combustion chamber.

14. A device as claims in claim 13, wherein the two pistons are flanked by two further combustion chambers.

15. A device as claimed in any one of claims 6 to 14, wherein the pistons are provided with axially arranged passages through which pass a continuous shaft, said shaft being provided with keying members, and said pistons being provided with grooves to receive said keying members to prevent relative rotational movement between said shaft and said pistons, said shaft passing through each of said combustion chambers.

16. A device as claimed in claim 6, wherein there is provided an external cylindrical sleeve arrangement defining passageways for water-cooling, oil supply and air and exhaust gas flows, inlets and outlets for said flows being spaced axially and/or radially around the circumference of the cylinder.

17. A device as claimed in claim 16, wherein at least the gas flows are controlled by electromagnetic valves operating in tangentially offset flow inlets/outlets.

18. A device as claimed in either one of claims 1 and 6, wherein at least one end face of said pistons is provided with a cylindrical flange extending axially therefrom in the form of a skirt.

19. A device as claimed in claim 18, wherein the skirt is provided with apertures arranged to coincide with flow inlets and outlets in turn at appropriate stages in the operating cycle in the manner of a sleeve valve.

20. A device as claimed in any of the preceding claims, wherein the output member is provided with turbine or similar propeller blades to permit a by-pass air flow, additional fuel injection means being provided to achieve an after-burner arrangement.