The present invention relates to a piston internal combustion engine.

Known piston internal combustion ^* engines comprise one or more rectilinear axis cylinders and a corresponding number of pistons housed inside said cylinders and connected, through a piston rod, to a crankshaft forming the drive shaft. When operating, each piston is subjected to a reciprocating axial motion, which is transformed into a circular motion of the drive shaft by means of the coupling piston rod-cranκ. The correct sequence of phases in the operating cycle of the engine is ensured by connections of the cylinder with the feeding and the exhaust and by a distribution system, usually a valve distributor, which opens and closes said connections synchronously with the rotation of the drive shaft. A drawback of these piston internal combustion engines consists in that the conversion of the reciprocating motion of one or of the pistons into rotatory motion of the drive shaft causes a periodic variation of the arm producing the thrust moment, and this requires, in order to have a substantial uniformity of the rotatory motion of the drive shaft, a certain number of cylinders and/or the use of flywheels, with an obvious increase of load, encumbrance and energy consumption.

A further drawback consists in that the distribution system which enables to correctly carry out all the operating cycle phases causes a further constructives and operating complexity of the engine, for which only partly the use of two-cycle engines rather than four-cycle engines has enabled to find a remedy, and this with the addition of other drawbacks well known to the skilled-man.

Aim of the invention is to eliminate all these drawbacks and to realize an internal combustion engine in which the thrust arm of the moment applied to the drive shaft is constant.

An other aim of the invention is to realize an internal combustion engine, in which the distribution system to carry out the correct sequence of the various phases of the operating cycle, has a very easy construction and a reliable and sure operating.

These and further aims which will result from the f o llowing description are at tained, according to the invention, by an internal combustion engine characterized by c o m p r i s i n g : - a stator a rotor housed inside said stator and provided with a drive shaft,

at least one toroidal cylinder housed inside said rotor and having its axis concentric with the rotation axis of said rotor, a toroidal piston movable with reciprocating motion inside said cylinder and connected, through a piston rod, to a crankshaft parallel to said drive shaft and provided with a cyclic train coupled to a fixed gear coaxial to said drive shaft, and a feeding ^' , ignition and exhaust unit, connected to said cylinder to carry out a complete thermic cycle of internal c o m b u s t i o n .

The present invention is hereinafter further clarified with reference to the enclosed drawings in which: figure 1 shows in cross section view an internal combustion engine according to the invention, figure 2 shows it in a partial axial sectional view, without cylinders and pistons, figure 3 shows it in -the same view as figure 1 in a different operating phase, and figure 4 shows the enlarged particular of the seal of each combustion chamber. As can be seen in the drawings, the engine according to the invention, which has been represented in a two cylinder

embodiment, comprises an outer cylinder-shaped stator 1, provided with two channels 2 and 3, respectively an intake and a discharge one. Two different grooves 4 and 5, which are provided in the internal surface of the stator 1, depart from these channels and extend in a circumferential way along an arc of about 90C, one after the other. in a position substantially spaced equally apart from the two grooves 4 and 5, in the body of the stator 1, a seat is provided for a spark plug 6 for the compressed mixture, as it will be better clarified.

A rotor 7 is housed in the cylindrical hollow of the stator 1. This rotor 7 is box-shaped and can rotate with respect to a central shaft 8, integral to said stator l.

Inside the rotor 7, two cylinders 9,9' diametrally opposed are housed. They have toroidal outline, that is with their axis concentrically curved with respect to the axis of the fixed shaft 8. Inside each cylinder 9,9' a corresponding piston 10,10' slides, even with toroidal outline, fixedly bound through an arm 11,11', to a common diametral bracket 12, free of rotating with respect to said shaft 8.

In a symmetric position with respect to the rotation axis of the bracket 12, the feet of two piston rods 13,13'are articulated, having their respective heads articulated to

corresponding crankshafts 14,14'. To the same crankshafts two equal cyclic trains 15,15'are keyed, coupled to a f ixed central gear 16, having the diameter double of the diameter of these trains 15,15'. Each of the two crankshaft 14,14' is supported by the lateral walls of the rotor 7, in positions diametrically opposed with respect to the rotation axis of said rotor.

Furthermore the head of each cylinder 9,9' that is the end opposite to that one for the passage of the arm 11,11' communicates, through a duct 17,17', with the cy lindrical lateral surface of the rotor 7.

On the cylindrical outer surface of the body of the rotor 7, an annualr seat 18 is provided encircling the end of such a duct 17,17 ^" . inside this seat an annular member 19 and a small spring 20 are housed, said spring 20 pushing outwardly said member 19 thus causing a slight contact with the opposite statoric surface. To the outer circumf erential surface of said annular member 19, elastic rings 21 are applied which carry out the seal with the corresponding circumf erential outer surface of the seat 18.

To one of the two circular level bases of the rotor 7, through a flanged disk 22, a shaft 23 is applied, forming the drive shaf t .

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Due to expositive clearness reasons, in the present description all the members and means have been omitted which, even being necessary to the construction and operating of the engine according to the invention, can be acknowledged by the capacity of the skilled man. Particularly any information has been omitted concerning the used materials, the bearing or bronzine supporting systems, the lubrication, feeding and discharging of the exhausted gas.

To better understand the operating of the motor according to the invention hereinafter described it is taken asx. starting point that one shown in figure 1. At that point: the cylinder 9 is at the end of the intake phase of the mixture which has entered in it through the channel 2, the groove 4 and the duct 17, and has completely filled the cylinder 9 due to the configuration of bottom end of stroke of the piston, and the cylinder 9', after having completed the expansion phase, has just started the discharge phase of the exhausted gas through the duct 17', the groove 5 and the channel 3,

Obviously the above described instant is reached in a dynamic condition of the rotor 7 which, due to the previous expansion phase in the cylinder 9' and to the inertia of the

moving parts, goes on rotating in the way indicated by the arrow 24 in figure 1. On overcoming that starting point: the duct 17 is closed at the outerend by the lateral cylindrical wall of the stator 1, - the rotation of the rotor 7, to which the crankshaft 14,14' are connected, causes that these are led in rotation, due to the coupling between the corresponding cyclic trains 15,15' and the central fixed gear 16, the rotation of these crankshaft 14,14' causes the stroke of the pistons 10,10' inside their corresponding cylinders

9,9' up to their top dead center.

The stroke of the piston 10 causes the compression of the mixture in the combustion chamber, which substantially is formed by the duct 17, and by an eventual hole 25 provided in the head of the piston 10; the stroke of the piston 10' causes the discharge of the exhaust gas through the duct 17', the groove 5, which during this phase always communicates with the duct 17', and the channel 3.

After a rotation angle of about 90[, the mutual position of the various parts, shown in figure 3, is substantially the f o l l o i n g :

- the piston 10 is at its top end of stroke, and the mixture is compressed at the most in the combustion chamber, that

is now faced to the spark plug 6, and the piston 10' is also at its top end of stroke with the " exhaust gas gone out through the channel ^" 3 and with the duct 17' faced to the channel 2. During the stroke of the piston 10, from the bottom dead center to the top dead center, the increase of the pressure of the mixture in the chamber of the cylinder 10 propagates inside the hollow of the annular seat 18 until the bottom is reached, occupied by the small spring 20, and pushes the annular element 19 to adhere against the cylindrical surface of the stator 1.

When, as already said, the combustion chamber reaches the position faced to the plug 6, the spark is produced between its electrodes and the pressed mixture contained in the combustion chamber explodes. At the same time the rotation of the rotor 7 goes on and therefore the two pistons 10,10' overcome their top dead center; in the cylinder 9 the expansion phase starts which pushes forward the rotor 7 and, consequently, withdraws the piston 10 which discharges the received energy on the fixed central gear 16, through the crankshaft 14 and the cyclic train 15. At the same time the piston 10' starts the intake phase of new mixture through the channel 2, the groove 4 and the duct 17'.

After a further rotation of 90[ from the instant when the spark has f lashed, the rotor 7 is in the configuration shown in figure 1, but with the cylinders 9,9' in inverted position. Substantially the operating of the engine according to the invention foresees that the two pistons 10,10' are act uat ed in oscillatory circular motion and that one semioscillation among four represents the active stroke, which is always simultaneous in the two cylinders 9,9' and which feeds the unidirectional rotation of the rotor 7, unloading its reaction on the central gear 16, integral to the stator 1.

Clearly at the rotation of the rotor 7 corresponds the rotation of the drive shaft 23. From the above it clearly results that the operation of the engine according to the invention is based on a principle completely new and original which presents, among the others, the following advantages: an active phase for each cylinder 9,9' and for each rotation of the drive shaft 23,

- a constant arm of the thrust moment to the drive shaft 23, a high constructive simplicity due to the elimination of any distribution apparatus,

a high balancing of the rotating parts, due to the symmetrical arrangement of the pistons, the possibility of using glow plugs other then electrode plugs, since the synchronization for the explosion phase is in any case due to the passage of the combustion chamber in front of the plug 6. This allows to eliminate the various elements which nowadays are necessary to cause the synchronized ignition of the plug (coil, electronic ignition and so on), a particular sealing system, which occurs only during , the compression and expansion phases, that is only in the phases in which such a seal is required, thus considerably reducing the wear of the involved parts, an easy replacement of the whole rotor, which is the only part containing p owe r mov ing m eans, and which is substantially the only one subjected to wear, the possibility of operating according to Otto cycle or Diesel cycle and practically with any fuel, as well as with a two-cycle system, obviously by previous execution of the necessary contrivances and arrangements, a very limited number of moving parts (six in the shown e m b o d i m e nt ) , a stratification of the mixture, due to centrifugal effect,

toward the outside of the combustion chamber, and therefore toward the plug 6, thus enriching the same mixture in that zone and enabling the use of poorer fuels.

In the above described embodment the engine with two cylinders 9,9' presents two active phases (one f or each cylinder) for each rotation of the drive shaft 23 and forms a basis unit which can be used alone or coupled with other units to an only drive shaft. For example, in the case of , two coupled units, the moving part are nine in all.