Internal-combustion engine having opposed integral annular pistons and a central shaft

Claim 1

Internal-combustion engine, comprising at least one driving shaft (8), driven in rotation by at least one engine assembly which the shaft penetrates coaxially (AA) (8), and which comprises a cylindrical housing (4), each axial end of which is integral with one of two hollow and annular cylinders (5), open towards each other and each closed by a base (5a) on the opposite side, and two annular pistons (2,3) guided in axial translation in the housing (4) in which they are fitted opposed, so that each of them exhibits a piston head (9) engaged to slide fluid-tightly in axial reciprocation each in one of the two annular cylinders (5), in each of which an annular combustion chamber (12) is delimited between the corresponding cylinder base (5a) and the piston head (9), each combustion chamber (12) being supplied by an admission system (10, 30, 29, 28, 25) for a comburent gas and/or a fuel and being in communication, through an exterior radial wall (15) of the corresponding annular cylinder (5), with a combustion gas exhaust system (16, 31, 32), the two pistons (2, 3), the housing (4), the two cylinders (5) and the shaft (8) being fitted coaxially about the longitudinal axis (AA) of the shaft (8) and the reciprocating axial movements of the pistons (2, 3) being converted into rotation of the shaft (8) about its axis (A) by a movement conversion mechanism coupling the pistons (2, 3) to a central part (19) of the shaft (8), and comprising pawls (22), one end of each of which is compelled to follow endless undulations, circumferential (20) about the axis (AA) and of the same axial amplitude, which are exhibited by a rigid member, wherein the two pistons (2, 3) are mutually integral by their bases and form a monolithic piston block (1), a central element (1a) of which slides in the housing (4) so that the two pistons (2, 3) move simultaneously in the axial direction and alternately in each sense, and in that the pawls (22) of the movement conversion mechanism are radial pawls, retained in one of the two rigid members formed by the central part (19) of the shaft (8) and by the central element (1a) of the piston block (1), whereas the undulations (20) are defined by at least one groove made in an axial surface of the other rigid member, and in which or in each of which, one end of each radial pawl (22) is engaged, the piston block (1) comprises, at each of its axial ends, an axial double skirt (2a, 3a) comprising two annular crowns (9, 10) coaxial about the axis (AA) of the shaft (8) and mutually spaced radially, and one of which (9), in the outer radial position, forms said head of the corresponding annular piston (2, 3), sliding in the corresponding annular cylinder (5) and comprising outer and inner radial segments (34), sliding against the outer (15) and inner (13) walls respectively of said annular cylinder (15), whereas the annular crown in the inner radial position (10) on the double skirt guides the piston block (1) in its axial movements by sliding within the inner wall (13) of said annular cylinder, the inner annular crown (10) of each double skirt of the piston (1) is hollow and comprises a flat and radial ring (10) which is spaced axially from the central element (1a) of the piston block (1) to which it is attached by at least one substantially axial and rigid column (10a) and which slides axially fluid tightly in an annular ante-chamber (30) delimited between the inner wall (13) of the corresponding annular cylinder (5) and a coaxial sleeve (35), surrounding the shaft (8) and fixed relative to said cylinder (5), the flat ring (10) of each inner crown is provided with axial apertures (11a) distributed regularly over its surface and associated with valves (11), so that the inner crown, with the antechamber (30), forms an admission pump for comburent gas and/or fuel into the corresponding combustion chamber (12), and in which the valves (11) are intended, on the one hand, to open the passage through the apertures (11a) into the interior of this inner crown, when the latter moves with the head (9) of the corresponding piston (2, 3) towards the base (5a) of the corresponding cylinder (5), to admit into this hollow inner crown (10) comburent gas and/or fuel available in the antechamber (30), and, on the other hand, to close the apertures (11a) when this inner crown (10) moves with the corresponding piston head (9) towards the other cylinder (5), in order to deliver comburent gas and/or fuel into said combustion chamber (12) through orifices (14) provided in the inner wall (13) of the corresponding cylinder (5).