GB2136546A - High thrust propulsion unit - Google Patents

Abstract

A propulsion unit for supplying very high thrusts with reduced thrust areas comprises inside a frame (3) a member (10) adapted to produce energy and to bring about an axial thrust action. The rotation of a platform (37) around a shaft extending transverse to the thrust axis causes a plurality of masses (79) to move radially under centrifugal reaction. The masses (79) travel one behind the other onto an active shoe area (25) of said energy producing member (10) to receive and oppose said thrust action. The platform (37) is moved in rotation by an independent engine (40) and the centrifugal masses (79) are returned towards the centre of the platform (37) by a fixed return cam (99) as they rotate away from said member (10) towards the diametrically opposite side of the frame (3). <IMAGE>

Description

SPECIFICATION High thrust propulsion unit The present invention relates to a propulsion unit the frame of which receives a powerful unidirectional thrust as a result of very high thrust actions acting on relatively small thrust areas. The thrust received by the frame may be significantly greater, for example, than that supplied by an aircraft propeller and may be even g reaterthan that of a jet engine.

The present invention provides a propulsion unit comprising frame defining a longitudinal axis, at least one member disposed inside said frame and adapted to produce energy and adapted to bring about a thrust action directed along an axis parallel to said frame axis, said member having an active area transverse to thethrustaxis,a platform supported by said frame and rotatable about an axis which is transverse to said thrust axis, a plurality of rod means mounted to said platform, a plurality of centrifugal masses, each mass being mounted to a respective one of said rod means, each mass having outer surface means, said masses being mounted in such a mannerthaton rotation of said platform the masses move radiallyto place themselves in succession aligned with said thrust axis, and with theiroutersurface means co-operating with said active area of said member so that said outer surface means receive and oppose said thrust action, asa resultofwhich a corresponding unidirectional thrust is imparted to the frame of said member, independent drive means for rotating said platform, a return cam fixedly mounted on said frame, said cam being operative to direct said masses radially inwardly aftertheir co-operation with said active area, a launching cam for acting on said massesafterthey leavethe influence ofthe return camtodirecttheir motion radially outwardly, and peripheral guiding means on said platform forslidably supporting said rod means.

The present invention also provides a propulsion unit comprising aframe, a platform rotatably mounted in said frame about a first axis, means for generating reciprocal motion of a shoe disposed at one end of said frame, said motion being along a second axis transverse to said first axis, a plurality of means mounted to said platform which successively come into contact with said shoe on roation of said platform as said shoe is trying to move in one direction along said second axis so asto resist said motion and cause said reciprocating means to subjectsaid frame to a force in the other direction along said second axis.

Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a vertical sectional view through a propulsion unit according to the invention; Figure 2 shows a partly cross-sectional view taken along line ll-ll of Figure 1; Figure 3 shows a vertical sectional view of an embodiment of the propulsion unit driven bytwo cylinder/piston systems symmetrically arranged; Figure 4 shows on an enlarged scale a front view of a detail of a portion of Figure 2 showing a mass engaging a surface of the thrust member; Figure 5 shows a sectional view along line V-V of Figure4; Figure 6 shows a vertical sectional view of a further embodiment of a propulsion unit; and Figure 7 shows a partial plan view of another embodiment of a propulsion unit in which the thrust producing member is a compressing spring.

With reference to Figures 1 and 2, the propulsion unit comprises a frame 3 constituted by a pair of longitudinal U-sections 5, spaced from each other and joined together by a pair of uprights 7 also made with U-shaped sections. Inside the frame 3, adjacent to the upright 7 to the left in Figure 1, a member 10 isfixed which, as a result ofthe rapid combustion of a fuel such as gas, is able to produce an axial thrust action.

As illustrated in Figure 1,the member 10 is a cylinder/piston system of a two-stroke internal com bustion engine 10. The engine 10 has no crank gear, but its piston 9 is joined with a rod 13 slidable along the axis of a cylinder 11. The cylinder axis is parallel with the longitudinal axis of symmetry of the frame 3.

The engine 10 is diagrammatically represented on the drawing and the suction and discharge members have been omitted. The engine 10 could be any suitable internal combustion engine, two orfour-stroke, running on petrol or gas, orfuel oil, and operating therefore according to the relevant cycles. The illustrated two-stroke engine 10 is fitted with a sparking plug 15 or a petrol ora diesel oil or a fuel oil injector generally in an explosion chamber 17, as well as with a casing 19, the inside of which, in the case of a 2-stroke engine, participates in the so-called scavenging phase. A pin 13 is joined at 21 to a transverse pin ofthe piston 9 so as to slide axially inside a guide 23 fixed to the casing 19.Suitable sealing means (not shown) may be provided to prevent leaks offluid from the casing 19 to the outside through the guide 23. The pin 13 having come out of the guide 23 is joined to the centre of a shoe member 25 the faces of which correspond to substantially parallel portions of cylindrical surfaceswith axesperpendiculartothe plane of the drawing of Figure 2. Afirst surface ofthe shoe member 25 is therefore delimited by a chain line rectangle two parallel sides of which are arcs of a circle and the other vertical sides of which are straight lines perpendicularto the plane ofthe drawing of Figure 2.

As will be subsequently illustrated,the concave shoe member 25 has a substantiallyT-shaped section, with the legdirected towards the platform, for a purpose to be made clear hereinbelow. The shoe member 25 has on the engine side, a forked projection 27 to which the pin 13 is joined. The member 25 also has four columns 29 parallel with the axis ofthe motor 10 and fixed atthe corners ofthe shoe member. Each column 29 is slidable in pairs of bushings 31, solid with the frame 3.

More precisely, there are fixed to the frame 3 on both sides ofthe engine 10 C-shaped plates which protrude towards the outside of the frame, and inside which the bushings 31, suitably separated in a longitudinal direction, are fixed. In this way the shoe member 25 is guided in such a way as to be able to slide together with the pin 13 in both directions along the axis of the engine 10 when the piston 9 performs both its inward or compression stroke, and the return or expansion stroke.

In the absence ofcrankgearing, to control the compression stage ofthe piston 9, a series of pairs of identical eccentrics 35 are provided. The eccentrics 35 are fixed to a circular platform 37 set in rotation by its own engine 40, which is entirely independent of the engine 10, and which may be of any type, provided it has the necessary power to effect the rotation of the platform 37 at the speed best suited forthe operation ofthe propulsion unit 1. The engine 40 controls the rotation ofthe platform 37 by means of a chain (or toothed belt) transmission 39. The platform 37 rotates about an axis perpendicularto the internal faces ofthe sections 5 and which intersects the longitudinal axis of symmetry oftheframe.The frame, by means of a hub 47, is solid with a shaft 41 the ends of which are in turn borne by bearings 43 and 44, of supporting and thrust type, fixed to the sections 5. The platform 37 is provided in addition with gussets 45 intended for straightening which connect itto the hub 47. The hub 47 is solid with a toothed wheel 49 which, by means of thetransmission 39, is driven from a pinion 51 solid with the output shaft of the engine 40.

To facilitate assembly, on the upperface of platform 37, opposite the toothed wheel 49, plates55E and 55M are applied with appropriate fixing means. These plates are alternated and are each in the shape of a sector of a circle. The plates are identical and there are eight of them which, placed side by side, coverthe entire face of the platform. The plates 55E and 55M may also exceed eight in number but, as they must alternate, their number must always be even. On each plate 55Ethe pairs of eccentrics 35 are fixed. The eccentrics are suitably shaped plates of reduced thickness. The lower eccentric 35B of each pair is inserted inside a suitable recess in the plate 55E. The uppereccentic35H is fixed to said plate and to the eccentric 35B by means of posts 57, drilled internally and through which fixing screws pass.The posts 57 have attheir ends portions of smaller diameter (not shown) for insertion into holes defined in the eccen trics 35B and 35H in such a mannere asto cause the latter, in operation, to assume a rigorously identical attitude. The profile 35P of each eccentric 35 begins substantially tangential to, and as a continuation of, the arc ofthe circumference ofthe plate 55M contiguous to it. The profile 35Pthen moves away outwardly, progressing in the fashion necessaryfor the piston 9to perform its proper compression stroke, when the platform 37 rotates in the direction ofthe arrow f37. The action ofthe pairs of eccentrics 35 is transmitted to the rod 13 bya pair of parallel rods 59 which extend fork-wise towards the centre of the platform from the concave portion of the shoe member 25.The rods 59 each end in a fork 61 within which a roller 63 can revolve, supported on, and following the profile ofthe corresponding eccentric 35. The rollers 63 each rotate about a short shaft 65 supported bytheforks 61. On each side ofthe shoe member 25 a tie rod 69 connects the end of each rod 59 inthevicinityofthefork61 with a point71 on the outside edge of said member 25, to prevent lateral deformations ofthe rods 59 due to the action ofthe eccentrics 35.

Onto the plates 55M which alternate with the plates 55E, small blocks 73 which are substantially para llelepipedic are applied in thevicinityofthe arcuate edge. Inside said blocks guide holes 75 are drilled so that rectilinear rods 77 may slide in a radial direction.

Centrifugal masses 79 are fixed atthe outwardly directed ends of said rods. At the opposite ends of the rods 77 small prismatic blocks 81 are fixed. As a result ofthe rotation of the platform 37, the centrifugal masses 79 are pushed outwards, bycentrifugaf reaction, along a path which is restricted by the presence ofthe blocks 81 whentheyabutagainstthe innerwall ofthe blocks 73.

It is importantto notethatthe centre line of each block 73 which passes through the centre C of the platform 37, defines an angle awith the radius which joins the centre C with the furthest projecting corner of the nearest eccentric35B in the direction of the arrow 37. The shape of the centrifugal masses 79 mayvary, but they are preferably substantially parallelepipedic and will be better described hereinbelow. The masses exert at the start ofthe expansion stroke, an action opposing the movementtowards the centre ofthe piston 9 and ofthe rod 13.As soon asthe compression phase due to the action ofthe eccentrics 35 on the rollers 63 is completed, the expansion stroke immediately follows which is caused by very fast combustion of the fuel insidetheexplosion chamber 17. The value ofthe angle or and the maximum radial path length of each centrifugal mass 79 are selected in such a manner so that, shortly beforethe expansion stroke starts (i.e.,the piston 9 startsto move in the direction ofthe arrowfg, a centrifugal mass 79 places itself in alignment with and in contact with the shoe member 25, opposing its centripetal movementwholly or partly.As a consequence of this, the high pressurewhich prevails atthe time ofthe explosion or combustion in the combustion chambercauses a high thrust force to be applied to the piston and to the cylinder head.

The start ofthe explosion or combustion, i.e. the production ofthe ignition sparkorthe injection ofthe fuel, is controlled by means of elements (not represented) connected with the most extreme part ofthe eccentric 35 or by the eccentrics themselves, an instant after, or even slightly before the end ofthe compression phase.

As the combustion insidethe explosion chamber 17 and the rotation ofthe platform 37 continue, the rod 13 continuesto push the shoe member 25 towards the centre C. The member 25is braked in this centripetal movement bythe thrustwhich the centrifugal mass 79 exerts on the concave surface 25C. This action is regulated in such amannerasto besmallerthan, or equal to, the th rust the piston 9 on the shoe member 25. Meanwhile, the centrifugal mass 79 runs along said surface 25C almost without friction or with slight friction, until it leaves it. At this point, the expansion stage ofthe piston 9 is completed and the roller 63 did not come into contact with the periphery ofthe plate 55M, are shifted towards the centre of a path equal to the stroke ofthe piston and are in a position to be again engaged by thefollowing pair of eccentrics 35to cause piston 9 to perform another compression stroke.

The sliding with slightfriction ofthe centrifugal masses 79 against and in contact with the surface 25C may be obtained with various systems. An exemplary system is shown in detail in Figures 4 and 5. Each centrifugal mass 79 has at the head a channel-shaped cavity, with a wide V section, with vertical lateral edges 91 alongside. In the edges 91 supporting holes 93 are drilled for shafts 95 for a plurality of rollers 97 (three in the drawing) having the shape of two truncated cones with their larger bases adjoining.

The lateral surfaces of the rollers 97 are not in contact with the bottom of the cavity 89. In use, when a centrifugal mass has to press against the shoe member 25 from below, the rollers 97 are in fact in contact with, and run on, a wide-V-shaped track 85, hollowedoutfrom awide rib 83 which protrudesatthe centre of the surface 25C. In this way, orwith other similar arrangements, the desired result is easily obtained. Otherarrangementsmay be provided to prevent a centrifugal mass 79 suddenly coming into contact with or losing contact with the shoe member 25.

It is necessaryto ensure that during the outward movement ofthe centrifugal masses 79 by centrifugal action no force is applied to the frame 3which could give rise to a component of high magnitude directed in a sense opposite that of the thrust action in the direction ofthe arrowf3 supplied to the frame 3 during each combustion and expansion cycle ofthe engine 10. Accordingly, each centrifugal mass 79, after having exerted its braking action, i.e. opposition,to the expansion stroke of the piston 9, is made to return as close as possible to the centre C, which said mass moves round an arc of slightly less than 1800 until it reaches the opposite side ofthe platform to the shoe member 25.This aim is achieved by means of an are of return "cam" 99, fixed inside and below (in the drawing), the U-section 5, the base of which is positioned so that its external surface faces towards the plates 55E and 55M. The return "cam" 99 is in reality a rod with an inwardly curved rectangular section. The concave face of the rod is turned towards the centre C. The rod itself is curved with a curvature which increases progressively. The internal surface 99S ofthe rod is at the maximum distance from the centre at its end 991, and is situated atthe minimum distance from the centre at its other end 99E.The return cam 99 exerts its action of bringing the centrifugal masses 79 closer to the centre after they have left the shoe member 25 and, therefore, is kept completely or almost completely free from the part of the frame 3 along which said masses run after leaving the shoe member. The return action is exerted by the cam internal surface 99S on idle rollers 101 supported on the end 1 03E of posts 103 protruding in a direction perpendicularto the top of each ofthe blocks 81.On looking at Figure 1 and following the outline of platform 37 in the direction ofarrowf37 it will be seen that between the centrifugal mass 79, shown in contact with the shoe member 25 and in the position where it isfurthest away from the centre C, and the next mass there is a 90" interval. The third mass is spaced a further 900 from the second and is at the closest possible position to said centre. The fourth centrifugal mass 79 has already moved away con siderablyfrom the centre C.As it is not certain thatfor all the possible speeds of rotation ofthe platform 37 the centrifugal reaction which acts on a centrifugal mass 79 will be sufficientto return it, after leaving the return cam 99, to a position of maximum distance from the centre C in a single half turn, provision is further made fora launching cam 109. On a skirt 109M of an active portion of the launching cam 109, which is fixed, idle rollers 105 of each block 81 are guided so as to cause the associated centrifugal mass to be directed away from the centre C. The idle rollers 105 are each pivoted inside a fork hollowed out inside the blocks 81, which are prismatic with a section in the shape of an irregular pentagon. The fork is formed in the face of the block 81 opposite its mass 79.The lauching cam 109 is also fixed to the longitudinal section 5 of the frame shown at the top in Figure 1 of the drawings, by means of a hub 107 with which it is solid. Both the launching cam 109 and the hub 107 are drilled internallyto permitthe rotation ofthe shaft 41 with which platform 37 is solid. The launching cam 109 exhibits its maximum eccentricity on the side opposite the return cam 99, and in a position where each roller 105 has moved through an angle slightly greater than 900 from the longitudinal axis oftheframe 3.When a roller 105, and therefore the centrifugal mass 79, have gone beyond such a position, the centrifugal reaction to which the mass 79 is subject is sufficient to make it perform the further centrifugal displacementto bring it substantially to the level ofthe bottom surface 25C of the shoe member 25, so as to be able to run along it, exerting its opposing action in the manner illustrated in Figures4and 5.

The rotation of platform 37 performs two functions.

Firstly, by means of the pairs of eccentrics 35, the engine 10 perform the compression phase and the ignition or the injection of the fuel, and therefore the start of combustion is brought about or controlled.

Secondly, asthecentrifugal masses 79 come into contact with the shoe member 25 shortly afterthe compression stroke has ended, the thrust received by the piston 9 in the combustion and expansion phase is opposed, particularly during the first expansion phase during which thethrust is highest. The expansion phase is then completed afterthe mass 79 has leftthe shoe member 25 and is therefore free to move in a centripetal direction for a short period before the rollers 63 are engaged by a following pair of eccentrics 35.Where the engine loins oftwo-stroke type, during each complete revolution of the platform 37, four complete cycles ofthe engine occur, imparting an intense thrust action fourtimesto theframe 3 in the direction ofarrowf3.

Figure 3 shows an embodiment of the invention in which, instead of a single two-stroke engine 10, two engines disposed symmetrically with respect to a centre horizontal plane of the frame 3 are provided. In the embodiment of Figure 3,foreach engine lOand 10' a rotating platform 37,37' is provided. The platforms are solid with a common hub 47, which in turn is solid with a shaft 41' supported by bearings of supporting and th rust type. The shaft 41 ' extends beyond the lower bearing towards the bottom in Figure 3, and has a conical wheel 111 fixed at its end so as to engage another conical wheel 113 set at 900 to it.

The conical wheel 113 is fixed on the end of a shaft 115 of an engine 40', which is independent from the engines 10 and 10'. The engine 40' may be anytype: petrol, diesel oil, or electric, provided its power and characteristics are such as to be able to impart to the pair of rotating platforms 37 and 37' the speed necessaryforthe operation ofthe engines 10 and 10', and forthe centrifugal masses 79 and 79' to oppose efficiently the strokes of the respective shoe members 25 and 25' in the explosion (or combustion) and expansion phases.

The embodiment of Figure 3 is essentially similar to the previously described embodiments and includes pairs of eccentrics 35 and 35', rollers 63 and 63', rods 59 and 59', return cams 99 and 99', launching cams 109 and 109', and so on. As in this case there are available two engines 10 and 10', assumed to be two-stroke, it is preferred that the engines 10 and 10' should operate in phase and that the two engines and the remaining members should be substantially identical, so as to produce, in the direction of arrow f3, a powerful thrust equivalent to twice the thrust obtained from a single engine 10.

In the case in which the engine 10 and the engine 10' areoffour-stroketype (for the control ofwhich it is necessary, however, to have on platforms 37 and 37' other eccentrics in addition to the pairs of eccentrics 35) it may be preferable to have the engines operating out of phase so that ignition and expansion take place inonlyoneengineatatime,thus reducingthe intervals which, in the case of the four-stroke engine, would occur between one th rust and the next.

The propulsion unitdescribed isabletosupply repeatedly a very high thrust action, translatable into acceleration oftheframe 3, as the explosion (or rapid combustion) pressure in the explosion chamberofthe engine 10 can reach the val ue of approx. kg/cm2.

This pressure, orthe average value ofthe pressure in the expansion phase opposed bythe centrifugal masses 79, multiplied by the area ofthe upper surface ofthe piston, may produce, with piston diameters which need not be excessively great,thrustvalues of tens of thousands of kilos,though of short duration, butfollowing each other at very short intervals as a result ofthe high rotational speed ofthe platform 37.

Figure 6 shows an alternative embodiment of the propulsion unit in which the member adapted to produce the thrust action, as a resultofthe combustion of a fuel such as gas, is a reactor, i.e. a reaction turbine (jetturbine) 10". The turbine includes an air compressor, a co-axial impeller and afinal cone. In this case the thrust action, in the direction of the arrow f1 0" ', is continuous instead of intermittent, as in the case previously described. It is obvious, then, that it is advisable that the thrust of the exhaust gases issuing at the rear surface of the jet turbine 10' "should be directly opposed, that is to say, braked by the centrifugal masses 79' "without the presence of intermediate members, such as the shoe member 25 which is dispensed with.Also dispensed with are the eccentrics 35 and all the other members associated with them orwith the shoe member 25. It is clearthat in this unitthe platform 37' ", because of the absence ofthe eccentric members 35, can carry a greater number of peripheral guide blocks 73" 'for guiding the rods 77' ",at the outermost end of which there are fixed the centrifugal masses 79" '.In this way, the interval between the presence of one centrifugal mass 79' " and the next in co-operation with the exhaust 10" 'ofthejetturbine 10"'s of jet turbine can beverysmall with a sufficiently high speed of rotation of the platform 37' ".This interval may also be reduced by increasing the peripheral development of the centrifugal masses 79' ",remembering, however, that they must not interfere with each other when returned to the centre by the action ofthe fixed return cam 99' ".

Also In this propulsion unit the platform 37" 'is entrained in rotation by an independent enginer 40" ' by means of a chain transmission 39" ',49" ',51 " '.

The chain wheel 49" ' solid with the shaft41 'and the hub 47" '.This unit also includes a fixed return cam 99" ', and a fixed eccentric 109" 'similarto those illustrated previously.

It is clearthatthe employment of a jetturbine 10" ' can apply an even higher thrust action to the frame 3" ' than that obtainable with the use of alternating internal combustion engines having no crank gear.

This requires that a satisfactory solution is given to technical problems suçh as the cooling ofthe centrifugal masses, etc., which the presence ofthe jet turbine 10" implies.

Figure 7 shows a further propulsion unit in which the member adapted to produce energy is a compression spring 180 with its axis parallel to the axis of theframe 103. Figure7 issimilarto Figure2and in it the reference numerals for corresponding features are increased by 100 with respect to those used in Figure 2. In this unitthe energy produced is elastic energy which is stored by the spring as it is compressed and is then released repeatedlyto produce energy which act during the spring expansion on a shoe 125, mounted similarly to the shoe 25 ofthe unit of Figures 1 and 2.

More particularly, in the unit of Figure 7, a spring 180, disposed along an axid parallel with the longitudinal axis ofthe frame 103, has its uppermost end (in the drawing) resting inside a plate 182 which has a side edge 184. The lowermost part (in the drawing) of the spring 180 is housed inside a spigot and socket member 113, which has a flat bottom forthe proper support of the spring. The device 113 performs the same function as the rod 13 and has atthe bottom a tail 186 hinged at 188 on a yoke 127 of the shoe 125.

The plate 182 is surmounted buy a hub 190 having an axial threaded bore which receives a threaded bolt 192. The end ofthe bolt 192 is fixed in hinged manner on a fork 194 which protrudes from a plate 196 fixed to the wall ofthe box section 107 ofthe frame. The hub 190 has atthetopa hexagonal portion 190E by means ofwhich it can be rotated in order to varythe exposed length of the threaded bolt 192. By this means it is possible to alterthe initial compression ofthe spring and thereforethe amount of elastic energy produced bythespring during each expansion. Nuts 198 make it possible to lock, by a lock-nut action,the relative position ofthe hub 190 and ofthethreaded bolt 192.

The shoe 125 has substantially inverted T section, similarto thst of the shoe 25 of Figure 2. The base of the shoe 125 is rectangular and has, at each corner, a rod 129 arranged with its axis parallel with the axis common to the spring 180, the spigot and socket 113, the hub 190 and the bolt 192. The rods 129 are able to slide within bushings contained insidetubularguards 131, above which they protrude with extensions 1 29P on which sleeves 202 are fixed. The play ofthe rods 129 is limited when the sleeves 202 abut against the tubularguards 131.This limitsthedownward run (in the drawing) ofthe shoe 125 and therefore the expansion travel ofthe spring 180.The tubular guards 131 are each fixed to a pair of brackets 204 in turn fixed to bars 206 disposed transversely with respect two the stringers 105 of the frame 103, and fixed externally relative to them.

A platform 137 which is rotatable by an independent motor (not represented) disposed on the frame 103, preferably on the part opposite the spring 180, producesthe rapid rotation of a plurality of peripheral guide blocks 173 disposed nearthe edge ofthe platform and at equal angular distances on it. Within guide holes 175 of the blocks 173 rods 177 slide. On the outer end of these rods centrifugal masses 179 are fixed. In the example of Figure 7 the blocks 173 are four in number, angularly spaced at 90".

During rapid rotation of the platform 137 the centrifugal masses 179 move outwards, and by means of rollers 197 they come in contact with, and press against a track 185 disposed beneath the shoe 125.

TYhe track 185 may bearc-shaped with the centre of the arc on the axis of rotation of the platform 137 (cf.

the track 85 of Figures 4 and 5), or it may be straight, as shown in Figure 7. As shown in Figure 7 the straight track 185 is provided with an initial section 1851, external to the shoe 125, on the left on the drawings, which permits a gradual contact of the roller 197 with the track. Platform 137 rotates in the direction ofthe arrow137 and the centrifugal masses 179 reach their maximum distance from the centre substantially at the moment when the rollers 197 come in contactwith the track 185, pressing against the shoe 125 as they pass under it. Along the half turn performed beyond the shoe 125, the masses 170 are directed towards the centre by a return cam (not shown in Figure 7) similar to the cam 99 of Figure 2 which acts on rollers 201 able to rotate idle on rods 203 which protrude above blocks 181.The blocks 181 are fixed to the other ends of the rods 177. The return motion of the blocks 179 is limited as they abut against the corresponding block 173. As a result ofthe action ofthe return cam on the rollers 201, the masses 179 are brought to a position closest to the axis ofthe platform 137. The blocks 181 are moreover each fitted with a roller 205, which is also idle on a shaft supported by a fork 181 F. As the roller 205 comes into contact with a launching eccentric (not shown in Fig.7) butsimilartothatdenoted by 109 in Figure 2the mass 179 is directed radially outwardly. Both the return cam which acts on the rollers 201 and the launching eccentricwhich acts on rollers 205 are solid withtheframe 103.

The spring 180 is compressed at regular intervals as a resultofthe rotation of platfgorm 137 bytheaction of a series of pairs of eccentrics 208 fixed on it opposite to one another. The pairs of eccentrics are spaced by the same angular spacing that separates the axes of the blocks 173. The eccentrics 208 seen in plane view, i.e.

as represented in Figure 7, havesubstantiallythe shape of a right-angledtrianglewith an arc-shaped hypotenuse. Each eccentric is disposed on platform 137 in such a manner that an angle ss is defined between the shorterside and the radius aligned with the axis of the following centrifugal mass 179. A roller 212 ableto rotate idle abouta shaft 214 supported buy a fork 218 is provided to contact each of the eccentrics 208 (of which only the one fixed to the upper surface of platform 137 is shown in Fig. 7). Each fork218 is solid with a structure 220, substantially in the form of an isoceles trapezium, which protrudes below (in the drawing) the shoe 125.There are two structures 220 each fixed laterally to the shoe, and each carrying a fork218forsupportingoneoftherollers212.1nthis way, as a result of the action ofthe two rollers one above, and one below the plane of Figure 7, the compression ofthe spring 180 is effected in a balanced manner, while the rods 177 guiding the centrifugal masses 179 pass in the space between the structures 220 and between the rollers 212.

The operation ofthe propulsion unit of Figure 7 is similarto that of the other embodiments already described. The cycle starts atthe time when the pair of rollers 212 comes in contact with an initial portion 2081 of the profile of each eccentric 208. In such a phase the spring 180 is in a condition of maximum expansion, restricted only by the limit stops formed by the sleeves 202 fixed on the head ofthe rods 19. As platform 137 rotates, the rollers 212, pushed bythe remaining profile of the eccentrics 208 shiftthe shoe 125 upwards, effecting, by means of the spigot and socket 113, the compression of the spring 180.When, as in the instantaneous situation shown in Figure 7, the rollers 212 are released by the eccentrics 208, leaving the spring 180 free to expand (and to give backthe elastic energy stored), the rollers 197 of a centrifugal mass 179 come into contact with the track 185. At this time, the centrifugal mass 179 has reached,with the rotation ofthe platform 137a positionfurthestfrom the centre ofthe platform. The mass 179 thus presses under and against the shoe 125, exerting a braking action relative to the action ofthe spring 180 which expands, and thus moves said shoe downwards (in the drawing).Through such a braking action, at each expansion ofthe spring 180 and throughoutthetime when a centrifugal mass 179 is in contact with the shoe 125, the end of the spring 180 exerts through the plate 182, the hub 190 and the bolt 192, a thrust action in the direction ofthe arrow Fl 90 on the box section 107 of the frame 103.

Such athrustaction is repeated during each revolution ofthe platform 137, as many times as there are masses 179 and corresponding pairs of eccentrics 208. As the platform is rotated at a very high rate the centrifugal reaction ofthe masses 179 reaches values such asto brake, withouty preventing, the expansion of the spring 180, the frame 103 is subjected within each unit of time to a very high number of thrusts, the magnitude of which depends upon the force of the spring and the extent of each compression thereof.

It is clearthat in the construction shown in Figure 7, the elastic energy, first stored and then delivered by the spring 180, is supplied by the engine which keeps the platform 137 rotating, and the power of which must be suitably selected.

Claims (14)

1. A propulsion unit comprising a frame defining a longitudinal axis, at least one member disposed inside saidframeand adapted to produceenergyand adapted to bring about a thrust action directed along an axis parallel to said frame, said member having an active area transverse to said thrust axis, a platform supported by said frame and rotatable about an axis which is transverse to said thrust axis, a plurality of rod means mounted to said platform, a plurality of centrifugal masses, each mass being mounted to a respective one of said rod means, each mass having outer surface means, said masses being mounted in such a mannerthat on rotation of said platform the masses move radiallyto place themselves in succession aligned with said thrust axis,and with their outer surface means co-operating with said active area of said member so that said outer surface means receive and oppose said thrust action, as a result of which a corresponding unidirectional thrust is imparted to said frame, independent drive means for rotating said platform, return cam fixedly mounted on said frame, said cam being operative to direct said masses radially inwardly aftertheir co-operation with said active area, a launching cam for acting on said masses afterthey leave the influence ofthe return cam to direct their motion radially outwardly, and peripheral guiding means on said platform for slidably supporting said rod means.

2. A propulsion unit as claimed in claim 1, wherein said active area includes the surface of a transversely extending shoe, said surface defining an arcuate or rectilineartrack againstwhich the outer surface means of said centrifugal masses run and press to receive and oppose said thrust action atthetimewhen it is exerted.

3. A propulsion unit as claimed in claim 2, wherein the outersurface means are adapted to move over said shoe surface to brake the th rust action with low friction.

4. A propulsion unit as claimed in any one ofthe preceding claims, wherein arresting blocks are fitted to the ends of said rod means opposite said masses, and two rollers are carried by each said arresting block for engagement with said return cam and said launching cam respectively.

5. A propulsion unit as claimed in any one of the preceding claims, wherein said energy producing member produces heat energy to supply said thrust action as a result ofthe combustion of a fuel.

6. A propulsion unit in any one ofthe preceding claims, wherein said energy producing member is an internal combustion engine including a cylinder having an end fixed to said frame, a piston disposed within said cylinder, and an axial rod carrying such piston, said active area being the surface of a plate connected to said rod so asto be slidable as a unit with said piston and said rod, and wherein the unit includes piston control means including a plurality of eccentric means carried on said platform to cause said piston of said internal combustion engine to perform appropriate non-working strokes, said eccentric means being arranged alternately with said peripheral guiding means, the spacing therebetween being such as to cause one of said centrifugal masses to contact said active area of said plate atthe commencement of a working or expansion stroke of said piston within said cylinder.

7. A propulsion unit as claimed in claim 6, wherein said piston control means further includes a roller,a pair of rods projecting from said plate parallel with the longitudinal axis of said rod, said roller being mounted to the remote end of said rods and cooperating with said eccentric means, said cylinder including ignition orfuel injection means which are controlled by said eccentric means.

8. A propulsion unit as claimed in claim 6 or7, wherein there are two engines and two platforms and associated masses mounted within said frame, said platforms being coaxial.

9. A propulsion unit as claimed in claim 6,7 or8, wherein the or each engine is a two-stroke engine or a four-stroke engine.

10. A propulsion unit as claimed in anyone of claims 1 to 4, wherein sasid energy producing membercomprisesajetturbine including an air compressor, co-axial impeller and final expansion cone, the exhaust gases from said cone crossing said active area with which said surface means of said masses co-operate.

11. A propulsion unit as claimed in any one of claims 1 to 4, wherein said energy producing member includes a compression spring having two ends and an axis parallel with said frame axis, said active area including a transverse shoe on which one said end of said spring acts, the unit further including a plate on whichthe othersaid end of said spring restsandwhich is mounted to transmitthethrust of the spring to said frame, a series of pairs of eccentrics fixed at equal angular distances on the rotating platform,two rollers mounted to said shoe such that each eccentric of said pairs of eccentrics acts on onesaid roller to compress said spring, said pairs of eccentrics alternating with said centrifugal masses, and spaced therefrom such that a mass contacts the shoe as the spring startsto expand.

12. A propulsion unit as claimed in claim 11, further including means for setting the position ofthe spring before it is compressed, to regulate its elastic reaction when it is released, and guiding means for said spring to prevent lateral deflections during compression.

13. A propulsion unit comprising a frame, a platform rotatably mounted in said frame about a first axis, means for generating reciprocal motion of a shoe disposed at one end of said frame, said motion being along a second axis transverse to said first axis, a plurality of masses mounted to said platform which successively come into contact with said shoe on roation of said platform as said shoe is trying to move in one direction along said second axis so as to resist said motion and cause said reciprocating means to subject said frame to a force in the other direction along said second axis.

14. A propulsion unit substantially as herein described with reference to Figures 1 and 2 or Figure 3 and Figure 4 and 5, or Figure 6, or Figure 7, ofthe accompanying drawings.