WO1980002443A1

WO1980002443A1 - Internal combustion and injection thermal engine

Info

Publication number: WO1980002443A1
Application number: PCT/FR1980/000071
Authority: WO
Inventors: P Lavaux; N Hudowicz; J Payen
Original assignee: P Lavaux; N Hudowicz; J Payen
Priority date: 1979-05-07
Filing date: 1980-05-06
Publication date: 1980-11-13
Also published as: FR2456212A1; IT8021864A0; CA1145265A; EP0028225A1; IT1140845B; FR2456212B1

Abstract

Internal combustion and injection thermal engine comprising in each cylinder, an axial piston connected by a connection rod to a crankshaft and a hollow piston (6) which is arranged coaxially around the axial piston and which is driven in translation by small rods (19) hinged on to throws (20) which are driven by a cycloidal gear train comprising a satellite (21), a planetary toothed crown (22) and two pinions (24 and 25), the latter being offset on the crankshaft. The head (8) of the hollow piston separates a combustion chamber (10) from an induction chamber (11) and comprises openings (8a) closed by an annular valve (9) opening automatically towards the inside of the chamber (10).

Description

Internal combustion and injection thermal engine.

The present invention relates to internal combustion and injection thermal engines.

The engines according to the invention are of the type comprising at least one cylinder in which a piston moves which is connected to a crankshaft by a connecting rod.

Four-stroke engines are known in which the successive phases of admission, compression, expansion and exhaust take place during two successive rotations of the crankshaft. In known four-stroke engines, the fuel efficiency depends on various factors and it is not possible to optimize the efficiency due to interference due to the arrangement of the engine components.

An objective of the invention is to provide thermal engines of a new type in order to improve the conditions for filling cylinders, to improve thermal efficiency, to adapt the compression ratio to the power required, to determine with precision the dosage of the fuel as a function of the volume of air actually admitted into the combustion chamber and adapt the volumetric variations of the expansion chamber in order to prolong the expansion - and to use a greater part of the energy released by combustion.

Another object of the invention is to provide four-stroke thermal engines comprising an air intake chamber separated from the combustion and expansion chamber, so that it is possible to adapt the structure separately. of each chamber to its function and that it becomes possible to produce combustion during each revolution of the crankshaft.

The engines according to the invention are of the known type comprising in each cylinder an axial piston which is connected to a crankshaft by a connecting rod.

The objectives of the invention are achieved by means of engines in which each cylinder comprises a second hollow piston, which is arranged coaxially around the axial piston, which is moved in a reciprocated synchronized movement and out of phase with respect to the movement alternating axial piston and which comprises a cylindrical skirt in which the axial piston moves, a hollow disc placed across one end of said skirt and a valve which closes the openings of said disc and which opens automatically inwards of said hollow piston.

The hollow pistons are driven by two diametrically opposite links which are each articulated on a crankpin which travels along a cycloidal trajectory. Preferably, this cycloidal trajectory is a three-lobed cycloid with three vertices.

Each of the links is driven by a cycloidal gear train which comprises:

- a fixed planetary ring gear;

a satellite pinion which rolls on said ring gear and which carries an eccentric crank pin around which the head of said rod is articulated and a bearing coaxial with said satellite pinion;

a first pinion for driving in rotation said satellite pinion which is coaxial with said ring gear and which carries an eccentric bore in which said bearing is engaged and rotates freely;

- And a second pinion wedged on the crankshaft which drives the first pinion at a speed synchronized with that of the crankshaft.

According to a preferred embodiment, the planetary toothed ring is fixed on a biras which carries a bore which is engaged coaxially on the crankshaft, so that said toothed ring and said first pinion can be angularly displaced around the axis of the crankshaft, which rotates said cycloidal trajectory around its center and varies the phase difference between the alternating movements of the first piston and the hollow piston.

A motor according to the invention further comprises means such as screws or hydraulic jacks for adjusting the angular position of the arm which carries the planetary gear ring. The foot of each of the links is articulated on a slide which is constituted by a plate fitted into a flat cut in the external face of the skirt of said hollow piston, which plate slides in two slides parallel to the axis common to the two pistons. Each cylinder has a combustion and expansion chamber and an intake chamber, of variable volume, which are separated by the head of said hollow piston.

The end of each cylinder opposite the crankshaft is closed by a cylinder head comprising air intake ducts which are closed by an automatic valve which opens towards the interior of the intake chamber and the intake chamber comprises at least one lateral lumen which is closed by a flap which slides parallel to the axis of the cylinder and which comprises means for adjusting its position.

The invention results in new internal combustion and injection heat engines. Fuel injection takes place directly in the combustion chamber and / or in the air intake chamber.

The engines according to the invention have numerous advantages linked to the presence in each cylinder of a second hollow piston which envelops the axial piston and which is driven by an alternating movement synchronized with the reciprocating movement of the axial piston, but out of phase with respect to to this one.

A first advantage is that each cylinder is divided into two chambers of variable volume, which are separated by the hollow piston. One of these chambers serves as an air intake chamber while the other serves as a combustion and expansion chamber. As a result, the air intake and metering phases can take place simultaneously with the compression, expansion and exhaust phases and it becomes possible to obtain a four-stroke engine comprising a combustion and expansion phase. and therefore an engine time during each crankshaft revolution. Another advantage lies in the fact that the volume of air admitted during each cycle can be easily dosed by varying the height of the lower edge of a sliding shutter which closes an air inlet lumen in the admission room. The admitted volume varies linearly with the position of the flap. It is possible to linearly control the flow rate of the fuel injector in the flap position and thus obtain a mixture of air and fuel in proportions which remain substantially constant whatever the engine speed. An easily more precise adjustment of the fuel mixture is thus obtained than that which is achieved by vacuum systems, of the carburetor type, and also more precise than that obtained in injection engines of known type, thereby saving fuel. .

Another advantage is that the combustion which is delimited by two pistons makes it possible to obtain a compression ratio independent of the expansion ratio., while on piston engines, these two ratios are necessarily equal.

As a result, it is possible to build petrol engines having detent ratios greater than 10, since one is no longer limited by the risks of detonation of the fuel and the petrol engines according to the invention therefore have better efficiency. . Another important advantage lies in the fact that the maximum compression and the ignition take place no longer at the top dead center of the axial piston or even before passing through the top dead center in the event of advance to the ignition, but after the axial piston has already reached the top dead center and at a time when the axial piston has already taken a certain speed and when the two pistons move in the same direction. The expansion speed is therefore higher at the start of the expansion and a greater part of the energy is used to produce mechanical work at the start of the expansion, which has the effect of reducing the temperature of the engine and therefore of facilitating the cooling and also to reduce the losses of calories dissipated in the cooling circuits and therefore to improve the efficiency. It has been calculated that the average temperature during expansion would be of the order of 2,000 ° K for an engine according to the invention against 2,300 ° K for a four-stroke engine of the same dimensions.

Another advantage of the engines according to the invention lies in the fact that the minimum volume of the expansion chamber and therefore the compression ratio and the expansion ratio can be varied by pivoting around the axis of the crankshaft. arm which carries the cycloidal gear trains, which makes it possible to adapt these ratios to the filling of the engine and to improve the efficiency.

Another advantage of the motors according to the invention lies in the fact that the volume of the expansion chamber continues to increase after the axial piston has passed the bottom dead center because the hollow piston rises with a speed greater than that of the piston axial. This results in a higher expansion ratio. The resistant torque exerted on the axial piston during the start of the ascent is compensated by a motor torque which is exerted at this moment of the cycle by the hollow piston.

The average engine torque of an engine according to the invention having the same stroke and the same bore as a four-stroke engine is multiplied by a factor of approximately 1.5.

An engine according to the invention is an engine without controlled valves. The air intake in the intake chamber and in the combustion chamber takes place automatically through automatic valves and the exhaust also takes place automatically by side lights of the skirt of the hollow piston.

The passage sections of the calibrated valves of an engine according to the invention can be much greater than those of the valves which equip four-stroke engines because there is not on the same cylinder head an exhaust valve juxtaposed with a valve of admission. On the other hand, the duration of filling of the intake chamber extends over a fraction of a cycle which is of the order of 280 ° against 180 ° approximately for a four-stroke engine. As a result, the filling of the cylinder with combustion air remains good even at high operating speeds of the order of 8,000 revolutions per minute.

The following description refers to the appended drawings which represent, without any limiting nature, an exemplary embodiment of an engine according to the invention.

Figures 1 and 2 are axial sections of the motor perpendicular to each other. Figure 1 is parallel to the axis of the crankshaft and Figure 2 is perpendicular to this axis.

Figure 3 is a geometric figure which represents the hypocycloidal trajectory of the crank pin driving the hollow piston.

FIG. 4 is a diagram which represents the strokes of the pistons as a function of time.

Figure 5 is a perspective view of the cycloidal gear train driving the hollow piston.

Figure 6 is a section along VI-VI perpendicular to the axis of the pistons. Figures 7 to 14 are views showing the successive positions of the pistons during a cycle.

Figures 1 and 2 show by way of example an internal combustion engine with a single cylinder but of course, an engine according to the invention may comprise several cylinders. The engine comprises an engine block 1 which, in the example shown, is the block of a water-cooled engine comprising recesses la in which a coolant circulates. Of course, an engine according to the invention could be air-cooled.

The engine block 1 defines a cylindrical cavity of axis x x1 in which one. piston 2 moves in an alternating motion parallel to the x x1 axis. The axial piston 2 is connected by a connecting rod 3 to a crankpin 4a of a crankshaft of axis v v '. The crankshaft carries a flywheel 5 and a pinion 5a for driving auxiliaries, oil pump, water pump, dynamo, etc. All of this part of a piston engine is well known and there is no need to describe it in detail. An engine according to the invention is an engine with direct injection of fuel by injectors into the cylinder. It can be a petrol injection engine or a diesel engine.

A motor according to the invention comprises, in each cylinder, a second hollow piston 6, comprising a cylindrical skirt 7 which surrounds the axial piston 2, which therefore moves inside the skirt 7 as inside a cylinder . The piston 2 has seals and segments 2a which seal the sliding conta between the piston 2 and the skirt 7.

The skirt 7 also includes seals and segments 7a which ensure the seal between the hollow piston 6 and the cylinder 1. The head of the hollow piston, which is situated at the end opposite to the crankshaft, consists of a hollow disc 8 The disc 8 has air intake openings 8a. The hollow piston 6 further comprises an automatic valve 9 which closes or unmasks the openings 8a. According to a preferred embodiment, the automatic valve 9 has the form of a flat ring to which are fixed guide rods 9b, which are engaged in recesses of the disc 8. Each of these recesses contains a calibrated spring 9a which s 'presses on the disc 8 and on the end of a rod 9b and which keeps the valve pressed against its seat. When the pressure exerted on the upper face of the flat ring becomes greater than the pressure on the lower face by an amount greater than a threshold determined by the setting of the springs, the valve 9 opens automatically towards the interior of the hollow piston. The axial piston 2 and the hollow piston 6 define between them a cylindrical chamber 10 of variable volume, which is the combustion and expansion chamber of the fuel mixture.

The hollow piston 6 delimits with the walls of the cylinder and with the cylinder head 13 a variable volume chamber 11 which is an air intake chamber.

The end of the cylinder is closed by a cylinder head 13 comprising inlet ducts 13a which communicate with the outside.

The recesses 13a are closed by an automatic valve 12 which is a flat ring, of the same type as the valve 9, which is kept applied on its seat by calibrated springs 12a and which opens automatically towards the interior of the chamber 11 when the vacuum therein reaches a threshold which is determined by the calibrated springs 12a.

The intake chamber 11 further comprises one or more lateral lights 14 which make it communicate with a conduit 15 which communicates with the atmosphere. The lights 14 are arranged so that they are fully exposed when the hollow piston 6 is in bottom dead center. A flap 16 which slides parallel to the axis x x1 more or less closes the lights 14 according to its position.

The position of the lower edge 16a of the flap 16 defines the volume of air which is trapped in the chamber 11 when the hollow piston rises and which is then transferred entirely into the combustion chamber when the hollow piston completely scans the intake chamber. The volume of air admitted during each cycle varies linearly as a function of the position of the flap 16. The motor comprises means for adjusting the position of the flap 16. On fixed motors, at constant speed, these means are constituted by example, as shown in Figure 1, by a threaded rod 17 which is screwed into a threaded bore through the flap 16 parallel to the axis x x1. A knurled button 17a makes it possible to rotate the threaded rod which is extended by a guide rod 17b. The threaded rod 17 can be replaced by any other equivalent means making it possible to move the flap 16 parallel to the axis x x1 of the cylinder.

On vehicle engines, the flap 16 is connected by a linkage or by a cable to a control member of the pedal, zipper, lever or lever type, which makes it possible to vary the air intake as a function of the power required. of the motor. The sliding shutter 16 performs a function similar to that of the pivoting shutter a carburetor.

The hollow piston 6 moves inside the cylinder in an alternating movement which is synchronized with that of the axial piston 2 and which is out of phase with respect thereto. FIG. 5 is an exploded perspective view of one of the two trains of cycloidal gears which drive the hollow piston 6 and which are symmetrical with respect to x x1.

Only one of these two gear trains will be described below.

In the skirt 7 of the hollow piston, two diametrically opposite flats are cut. A slide, constituted by a plate 30 is fitted into each of these flats. The vertical edges of the slide 30, which have a triangular point shape, slide in two slides 31 parallel to the axis x x1. A single slide has been shown in Figure 5 for clarity of the drawing. Each slide has a bore 33 in which the foot 34 of a link 19 is articulated. The slide 30 has the effect of supporting the tangential component of the thrust of the link which it transfers to the slides in order to avoid risks of deformation of the skirt of the hollow piston The link 19 is articulated on a crank pin 20 which is driven by a cycloidal gear train. Each crank pin 20 is carried by a pinion 21 which meshes with the teeth of a fixed toothed crown 22 of axis u u1.

The axis y y1 of the crank pin 20 is offset by a length e relative to the axis z zl of the pinion 21 which carries it, so that when the pinion rolls around the ring gear, the center of the crank pin travels a trajectory cycloidal or trochoidal.

In the preferred example shown, the toothing of the ring gear 22 is internal and the pinion gear 21 rolls inside the planetary crown. The ratio between the radius R of the ring gear and the radius r of the satellite pinion is equal to 3 so that the center of the crank pin describes a three-lobed hypocycloid, of curvilinear triangular shape, having three vertices.

As a variant, the toothing of the toothed ring 22 could be external and the planet gear could then roll outside the toothed ring and then travel along an epicycloidal trajectory with three vertices also of curvilinear triangular shape.

Each satellite pinion carries a bearing 23 coaxial with the pinion.

Each satellite pinion is driven in rotation around the axis u u1 of the ring gear in synchronism with the crankshaft and this rotary drive causes the satellite pinion to roll on the teeth of the ring gear, so that the center of the crank pin 20 travels entirely through the cycloidal trajectory each time the crankshaft makes a revolution.

The drive in rotation of the satellite pinion around the axis u u1 is obtained by means of a first drive pinion 24, coaxial with the ring gear 22, which is itself driven in rotation, directly or by one or several intermediate pinions, by a second pinion 25 wedged on the crankshaft 4. The drive ratio is such that the pinion 24 rotates at the same speed as the crankshaft. Each pinion 24 carries an eccentric bore 35 in which is engaged the bearing 23 coaxial with the satellite pinion, which bearing can pivot freely in this bore.

The eccentricity of the bore 35 corresponds to the distance R-r between the axis z z1 of the satellite pinion of radius r and the axis u u1 of the ring gear of radius R.

The pinion 24 could be replaced by a drive arm of length R-r which would be rotated around the axis u u1 in synchronism with the crankshaft.

Each drive mechanism of the hollow piston has an arm or pendulum 36 on which the ring gear 22 is fixed. This arm 36 has a bore 37 which is engaged on the end of the crankshaft, so that one can angularly move the arm 36 around the axis v v1 of the crankshaft. The angular displacement of the arm 36 causes an angular displacement around the axis v v1 of the ring gear 22 and the pinion 24. The pinion 24 rolls on the pinion 25 and pivots around the axis u u1, which drives the satellite 21 rotating around its axis. As a result, the cycloidal trajectory of the crankpin 20 pivots around its center and at the same time, a variation of the phase shift between the alternating movements of the two pistons, which modifies the relative positions of the two pistons and has the effect of allowing '' adjust the minimum volume of the combustion chamber.

The arm 36 carries a second bore 38, in which is housed a bearing 39 supporting the pinion 24 and bearings 40 serving as axial stops.

The device comprises means for adjusting the angular position of the arm 36. In the case of a stationary motor which works at a uniform speed, these means can be constituted by screws

41. In the case of a vehicle engine which must supply variable powers, the screws 41 are replaced by hydraulic jacks mounted in opposition, so that one pushes the arm, while the other brakes the movement of the arm. Of course, in this case, the jacks which control the two movable arms 36 symmetrical with respect to the axis x x1 are coupled so that the angular displacements of the two arms are equal.

FIG. 3 is a geometric figure which represents the hypocycloidal trajectory T with three vertices traversed by the center of the crankpins 20. The vertical axis x x1 represents the projection of the axis of a cylinder. This figure shows two positions 19 and 19 'of the rods, 34, 34' of the rod foot which moves on the axis x x1 and 20, 20 'of the rod head. The primitive circle of the toothing of a toothed ring 22 of radius R and of center 0 and the primitive circle of the toothing of a satellite pinion 21 of center 0 'and of radius have also been shown.

represents the eccentricity e between the center of the crank pin 20 and the center 0 'of the satellite and the circle C traversed by the center 0' when the satellite rolls on the ring gear. The distance 0 0 ′ corresponds to the eccentricity of the bore 35 relative to the axis u u1 of the drive pinion 24a and represents the half stroke of the hollow piston.

The hypocycloid T has a vertex on the x x1 axis which corresponds to the top dead center of the hollow piston. In the example shown, the curve T is symmetrical with respect to the axis x x1 and it can be seen that during all the time when the connecting rod head traverses the side of the hypocycloid perpendicular to the axis x x1, the hollow piston remains substantially at bottom dead center. By rotating the arm 36 around the axis of the crankshaft, one can slightly rotate the curve T around its center 0 which itself moves slightly.

The skirt 7 of the hollow piston 6 has lights 26 visible in Figure 2 and the engine block 1 is traversed by exhaust pipes 27 which are in the vertical alignment of the lights, so that when the lights 26 are placed opposite the exhaust pipes 27 consequently the movement of the hollow piston, the combustion chamber 10 is exhausted.

The skirt 7 of the hollow piston 6 has a light 28 visible in FIG. 2 which is located near the head 8 of the piston and the body 1 carries a fuel injector 29 which can be connected to an injection pump or else be a electromagnetic injector. The injector 28 injects fuel: petrol or diesel. It is located on the path of the light 28 parallel to the axis x x1 and at the moment when the light 28 is placed opposite the injector, a dose of fuel is injected directly into the combustion chamber 10. As a variant , the injector 29 can inject into the mixing chamber 11 before the mixture is introduced into the combustion chamber.

The engine can also include two injectors: an idle injector which injects directly into the combustion chamber 10 and a normal speed injector, which injects into the mixing chamber 11.

A gasoline engine according to the invention comprises, in each cylinder, a spark plug 42 carried by the disc 8. This spark plug is housed in an insulating sheath 42a and extended by a conductive rod 42b which are housed in a well 43 which passes through the cylinder head 13, so that the rod 42b and the sleeve 42a slide in the well 43 when the hollow piston moves.

The sheath 42a is for example made of polytetrafluoroethylene. The rod 42b slides in a conductive sheath 43a which is isolated from the cylinder head by an insulating sheath 43b and which is connected on a wire 43c which connects it to the ignition distributor which controls the ignition at the moment when the compression of the combustible mixture is maximum. .

FIG. 4 is a diagram which represents the abscissa t and the angle θ = ω.t of the crankshaft expressed in degrees, ω being the angular speed of the crankshaft. The zero angle corresponds to the top dead center of piston 2. The diagram shows the piston strokes on the ordinate. The sinusoid S1 represents the displacements of the upper face of the axial piston 2. The curve S2 represents the displacements of the lower face of the valve 9 which equips the hollow piston and the curve S3 represents the displacements of the upper face of the disc 8 which constitutes the upper face of the hollow piston.

The duration of a cycle is the same for the two pistons whose movements are synchronized.

This diagram also shows the variable position of the light 26, the fixed position of the exhaust duct 27, the fixed position of the duct 15 and the level of the lower edge 16a of the movable flap 16.

The upper horizontal line 12 represents the level of the lower face of the valve 12. It can be seen in this diagram that the paths S2 and S3, which are obviously parallel to each other, have at the bottom point, a substantially horizontal level which corresponds to the path by the crank pin 20 of the hypocycloid portion which is substantially perpendicular to the vertical axis x x1.

It can also be seen that the passages in top dead center of the piston 2 and of the hollow piston 6 are phase shifted by an angle ø which is equal to 75 ° in the case of the figure, the hollow piston 6 being ahead of the axial piston 2 The phase shift ø can vary between 50 ° and 100 °. It is also seen that after passing through the top dead center of the piston 2, the two pistons both move in the same direction downwards at different speeds. When the piston 2 has just passed the top dead center its speed is low and the hollow piston goes faster until a time when the two speeds are equal. At this time, the distance a between the two pistons is minimum, the volume of the compression chamber is also minimum and the relative position of the two pistons at this time as well as the position of the lower edge 16a of the sliding flap 16 determine the rate compression and allow to vary the relaxation ratio.

We see in Figure 4 that in the example shown, the stroke of the hollow piston is equal to about two thirds of the stroke of the axial piston 2. Of course this ratio may vary depending on the type of engine desired.

Figure 6 is an unhooked section of Figure 1 along VI-VI. This figure shows a top view of the disc 8 comprising three oblong openings, in an arc, 8a for air passage which are closed by an annular valve 9 visible through the recesses 8a. We also see three guide rods 9b of the valve 9. The section of the openings 8a is large, of the order of a third to half the section of the chamber 10. We also see the fuel injector 29. We also see a section of the sliding shutter 16 and the guide rod 17b thereof. We also see the plates 30 which are partly fitted into the skirt of the hollow piston and whose two vertical edges are cut in the shape of triangular points which are engaged in triangular slides 31 cut in the body 1. We also see the rods 19 which are articulated on the pads 30. A wear part 44 is placed between each link and the engine body. The wearing parts 44 are also visible in FIG. 1. FIGS. 7 to 14 are schematic figures which represent different positions occupied successively during a revolution of the crankshaft by the two pistons 2 and 6. The operation of an engine according to the The invention will be explained with reference to these figures. It will be seen that the four times of an internal combustion engine take place during a single revolution of the crankshaft, since two times can take place simultaneously in two separate chambers: the intake chamber 11 and the combustion chamber 10 Therefore, an engine according to the invention is a so-called simultaneous time engine. There is shown in Figures 7 to 14 in solid solid lines, the axial piston 2, the connecting rod 3 and the circular path 4 of the head of the connecting rod 3 and there is shown in dotted lines a connecting rod 19, the three-lobed hypocycloidal trajectory T of the head of the link 19 and the hollow piston 6. The small white circles represent the combustion air and the dotted circles represent the burnt gases.

We start from FIG. 7 which corresponds to the top dead center of the axial piston 2 which has a delayed phase shift by an angle ø which is equal to 75 ° in the case of the figure.

FIG. 7 corresponds to the leftmost point of the diagram in FIG. 5. The positions corresponding to FIGS. 7 to 14 have been identified on the lower line of FIG. 5.

We will first examine what happens in the intake chamber 11 located between the piston 2 and the hollow piston 6. The fresh air intake phase in the intake chamber 11 begins after the hollow piston 6 has passed top dead center where the volume of the chamber 11 is zero. The intake phase continues throughout the time when the hollow piston moves between the top dead center and the bottom dead center, that is to say occupies the successive positions shown in FIGS. 7 to 12.

Under the effect of the vacuum which is created in the chamber 11 by the movement of the hollow piston, the valve 12 opens automatically as soon as the vacuum reaches a threshold determined by the calibration springs and lets fresh air in. in room 11 (Figure 10).

FIG. 11 represents the moment when the top of the hollow piston 6 arrives at the lower edge 16a of the movable flap 16. At this moment, air enters the intake chamber 11 through the conduit 15, the pressure in the chamber 11 becomes equal to atmospheric pressure and the valve 12 closes automatically. This combination of a valve 12 and a sliding flap 16 makes it possible to limit the value of the vacuum in the chamber 11 during the intake phase while controlling the quantity of air admitted. Figures 12 to 15 show the dosing phases of the combustion air. FIG. 12 corresponds to the passage of the hollow piston at level 16a during the upward movement of the piston. At this time, the communication of the chamber 11 with the conduit 15 is closed and the level 16a therefore determines the volume of air which is trapped in the intake chamber and which will be sent entirely to the combustion chamber. It can therefore be seen that by sliding the shutter 16, the level 16a is modified and the volume of combustion air admitted during each cycle is determined, which varies linearly with the position of the shutter 16. Between the positions shown in FIGS. 13 and 14 the air trapped in the chamber 11 is compressed to the position -represented in FIG. 14 where the pressure in the chamber 11 exceeds the pressure in the combustion chamber 10 and where the valve 9 opens automatically. FIG. 14 also corresponds to the position of the hollow piston 6 for which the exhaust ports 26 begin to be located opposite the exhaust duct 27. The fresh air which enters the combustion chamber 10 sweeps the burnt gases which escape through the lights 26 and this scanning continues until the piston 2 closes the openings 26 (Figure 8).

The combustion air intake and metering phases which have taken place during a cycle in the intake chamber 11 have been described.

The phases which take place simultaneously in the combustion chamber 10 will be described below with reference to FIG. 7 which corresponds to the end of the scavenging of the burnt gases.

FIG. 8 represents a position in which the piston 2 masks the openings 26. The volume of the chamber 10 decreases rapidly because the piston 2 goes up and the hollow piston 6 - goes down. The air contained in chamber 10 is compressed quickly.

FIG. 9 represents the instant when the light 28 is located opposite the injector 29 and when the fuel is injected into the chamber 10.

Figures 10 and 11 show the continuation of the compression phase.

Figure 10 corresponds to the passage of the piston 2 through the high point which does not correspond to the maximum compression ratio. Figure 11 corresponds to the moment when the speeds of. two pistons are directed in the same direction and are equal. The volume of the chamber 30 is then minimum and this volume determines the compression ratio. At this instant, combustion begins either by self-ignition in the case of a diesel engine, or under the effect of a spark which bursts at this moment between the electrodes of the spark plug 42.

The phase between Figures 11 and 14 corresponds to the expansion of the fuel mixture. During this phase, the two pistons 2 and 6 transmit an engine or resistant torque to the crankshaft and the final torque results from the addition of these two couples.

During the phase between FIGS. 11 and 12, the thrust of the gases exerts a driving torque on the piston 2 and a resistive torque on the piston 6. FIG. 12 corresponds to the passage of the hollow piston 6 through the bottom dead center. During the phase between FIGS. 12 and 13, the thrust of the gases exerts a driving torque both on the piston 2 which descends and on the hollow piston 6 which rises. The epicyclic gear driving the hollow piston transmits the torque to the crankshaft motor exerted by the hollow piston.

Figure 13 corresponds to the passage of the piston 2 through the bottom dead center.

During the phase between Figures 13 and 14, the two pistons rise and the volume of the chamber 10 continues to increase until the speeds of the two pistons are equal (Figure 14). The expansion of the gases therefore continues even after the piston 2 has passed through the bottom dead center by exerting a driving torque on the hollow piston which compensates for the resistant torque exerted on the piston 2. The light 26 is disposed on the hollow piston 6 so that it begins to be opposite the exhaust duct 27 when the volume of the chamber 10 is maximum (Figure 14). The exhaust begins at this time, at the same time as the valve 9 opens and the fresh air begins to sweep the burnt gases and the sweeping continues during the phases comprised between FIGS. 14, 7 and 8.

FIG. 7 corresponds to a phase where the head of the hollow piston 6 arrives substantially at the level of the cylinder head with a very small dead space, so that all the air trapped in the chamber 11 passes into the expansion chamber 10.

FIG. 8 represents a position in which the compression of the fresh air begins for a new cycle.

Theoretical calculations show that an engine according to the invention having an axial piston diameter of 73 mm, a hollow piston diameter of 84 mm, a crankshaft radius of 38.5 mm, a connecting rod length of 129 mm , a radius of the satellite drive arm of 23.1 mm, a length of rods of 68.3 mm, a crank eccentricity of 3.8 mm, a maximum admissible volume by the intake chamber of 224 cm, a compression ratio of 9.5, a phase shift ø = 75 ° between the movements of the two pistons and a volumetric expansion ratio of 15.17 develops over a cycle an average engine torque of 6.63 m.Kg, that the average temperature during expansion is 2.015 ° K and that the thermal efficiency, taking into account the volumetric ratios of expansion brought into play, is equal to 0.59. By way of comparison, for a four-stroke engine having the same diameter, same piston stroke and same compression ratio, an average engine torque is obtained over two revolutions of 4.12 m.Kg, an average temperature during expansion of 2.338 ° K and a yield thermal of 0.52.

The motors according to the invention have the advantage of making it possible to precisely dose the quantity of air admitted which varies linearly with the height of the lower edge of the sliding shutter which is moved to adapt the power of the motor to the power required. As a result, the control of the metering of fuel injected with the metering of air is easy to perform since it suffices to vary the quantity of fuel delivered by the injector in proportion to the position of the flap. Thus, whatever the power required, the motors according to the invention can be adapted to provide this power under the best performance conditions. Another advantage of the motors according to the invention lies in the fact that the compression ratio can be adjusted by rotating the cycloidal path T around its center and by varying the phase shift ø between the alternating movements of the two pistons. This adjustment is obtained by rotating the arm 36 around the axis of the crankshaft and the position of the arm can be controlled by the position of the intake flap 16 so as to always obtain the same compression ratio.

Claims

Patent claims.

1 - Internal combustion and injection thermal engine of the type comprising at least one cylinder (1) and an axial piston (2) which is connected to a crankshaft (4) by a connecting rod (3), characterized in that each cylinder ( 1) comprises a second hollow piston (6) which is arranged coaxially around the axial piston, which is displaced by an alternating movement, synchronized and out of phase with respect to the alternating movement of the axial piston, and which comprises a cylindrical skirt (7) in which the axial piston (2) moves, a hollow disc (8) placed across one end (7a) of said skirt and a valve (9) which closes the openings (8a) of said disc and which opens automatically towards the inside of said hollow piston. 2 - Motor according to claim 1, characterized in that said hollow pistons are driven in translation by two connecting rods (19) diametrically opposite, which are each articulated on a crankpin (20) which travels along a cycloidal trajectory.

3 - Motor according to claim 2, characterized in that said cycloidal trajectory is a three-lobed cycloid with three vertices

4 - Motor according to claim 2, characterized in that each of said links (19) is driven by a cycloidal gear train which comprises:

- a fixed planetary ring gear (22); - A satellite pinion (21) which rolls on said ring gear (22) and which carries an eccentric pin (20) around which the head of said link is articulated and a bearing (23) coaxial with said satellite pinion;

- a first pinion (24) for rotating said satellite pinion (21) which is coaxial with said ring gear

(22) and which carries an eccentric bore (25) in which said bearing (23) is engaged and turns freely;

- And a second pinion (25) wedged on the crankshaft (4) which drives the first pinion (25) at a speed synchronized with that of the crankshaft. 5 - Motor according to claim 4, characterized in that said planetary ring gear (22) is fixed on an arm (36) which carries a bore (37) which is engaged coaxially on the crankshaft (4), so that said gear ring (22) and said first pinion (24) can be angularly displaced about the axis of the crankshaft, which rotates said cycloidal trajectory around its center and makes the phase shift between the alternating movements of the first piston (2) and the hollow piston (6). 6 - Motor according to claim 5, characterized in that it comprises means such as screws or hydraulic cylinders for adjusting the angular position of said arm (36). 7 - Motor according to claim 2, characterized in that the foot of each of said rods (19) is articulated on a slide which is constituted by a plate (30) fitted into a flat cut in the external face of the skirt (7) of said hollow piston, which plate (30) slides in two slides (31) parallel to the axis common to the two pistons.

8 - Engine according to claim 1, characterized in that each cylinder comprises a combustion and expansion chamber (10) and an intake chamber (11) of variable volume which are separated by the head (8) of said hollow piston ( 6). 9 - Engine according to claim 8, characterized in that the end of each cylinder which is opposite the crankshaft is closed by a cylinder head (13) having air intake ducts (13a), which are closed by a valve automatic (12) which opens towards the inside of the intake chamber and the intake chamber (11) comprises at least one lateral lumen (14) which is closed by a flap (16) which slides parallel to the cylinder axis and which comprises means (17) for adjusting its position. 10 - Engine according to claim 1, characterized in that the skirt of said hollow piston has a lateral lumen (28) located near the head of the piston and the engine body carries an injector (29) which is located in alignment of said light parallel to the axis of the cylinder.