Rotary valve for internal-combustion engine

In an internal-combustion engine having a piston cylinder with a cylinder head operable in a multistroke cycle,

• the combustion therewith of a rotary valve driven by the engine and located in said cylinder head, said rotary valve comprising a first and a second annular shutter coaxially corotating in close contact with each other and having each two mutually opposite solid quadrants and two perforated intervening quadrants, said first shutter being synchronized with a reciprocating piston in said cylinder to perform half a revolution per cycle and being provided in the intervening quadrants thereof with first apertures registering with a pair of diametrically opposite outlet ports in said cylinder head during an exhaust phase and with a pair of diametrically opposite inlet ports in said cylinder head during an immediately following intake phase of the piston, said second shutter being synchronized with said piston to perform a full revolution per cycle and being provided in the intervening quadrants thereof with second apertures registering with said outlet and inlet ports during said exhaust and intake phases, respectively, said inlet ports communicating with a source of fuel/air mixture and being offset by 90.degree. from said outlet ports, said inlet and outlet ports being obstructed during a compression/ignition phase and during a subsequent expansion phase by the solid quadrants of at least one of said shutters.