Internal combustion engine of the reciprocating piston-type with multiple-valve cylinders

Claim 1

Reciprocating internal combustion engine of the type including an engine block with one or more cylinders in which or in each of which a piston is slidable, and a head structure which defines a combustion chamber in correspondence with the or each cylinder, and in which the or each combustion chamber has an associated pair of transversely opposed mushroom valves arranged in a V relative to the axis of the cylinder and having stems which are slidably mounted in the head structure, these valves cooperating with respective valve seats formed in the head structure facing the combustion chamber and at which terminate respective inlet and exhaust ducts formed in the head structure, characterised in that the head structure includes a cylinder head (22) and a separate inserted plate (18) clamped between the cylinder head itself and the engine block (10), in that the combustion chamber (24) of the or each cylinder (12) is formed in the cylinder head (22) in a position centered on the axis of the cylinder (12) and the inserted plate (18) has an aperture (26) centered on the axis of the cylinder (12) which puts the cylinder itself into communication with the chamber (24), in that the inserted plate (18), in correspondence with the or each cylinder (12), is formed with at least one first pair of opposing valve seats (28) facing the communication aperture (26) and with corresponding inlet and/or exhaust ducts (34), these seats (28) having associated mushroom valves (30) with stems which extend through corresponding holes (32) in the inserted plate (18) and are slidable in the cylinder head (22), in that the cylinder head (22), in correspondence with the or each cylinder (12), is formed with at least one second pair of opposing valve seats (38) facing into the combustion chamber (24) and with corresponding inlet and/or exhaust ducts (42), these seats having associated mushrooms valves (30) with stems which are slidable in the cylinder head (22), the axes of said two pairs of valves (30, 40) being substantially coplanar, and in that the crown of the or each piston (14) has a projection (60) of a form such as substantially to fill the communication aperture (26) when the piston (14) is at top dead-centre.