Method for injecting an oxidiser-fuel gaseous mixture

A method for injecting an oxidiser-fuel gaseous fuel mixture (1) into an ignition prechamber (2) which comprises a cylinder head (3) of a spark ignition reciprocating internal combustion engine (4), said prechamber (2) having at least one ignition torch emission opening (5) which opens into a main combustion chamber (6) which comprises said engine (4) and into which a main charge (40) consisting of an oxidiser (15) and a fuel (16) can be introduced, said engine (4) also comprising at least one crankshaft (7), at least one camshaft (8), and at least one gaseous fuel mixture injector (9) which opens into the ignition prechamber (2), said injector (9) comprising at least one injector needle (10) which can either rest in a sealed manner on a needle seat (11), said injector (9) then being closed, or can be lifted from said seat (11) by an electrically controlled injection actuator (12) controlled by a computer (13), said injector (9) then being opened, which has the effect of introducing into said prechamber (2) a pilot charge (39) formed of a gaseous fuel mixture (14) which consists of an oxidiser (15) and a fuel (16) and which has been previously pressurised by compression means (17), said mixture (14) having been formed in an oxidiser-fuel mixer (18), while the ignition (41) of the pilot charge (39) in the ignition prechamber (2) can be triggered by the computer (13) by means of a spark plug (19) which opens into said prechamber (2), characterized in that it consists in:

• Measuring, by means of a crankshaft angular position sensor (20), the crankshaft angular position (CA) to transmit to the computer (13) the angular position of the crankshaft (7) relative to that of the internal combustion engine (4);
• Using at least one filling electrical current profile (22) that can be applied by the computer (13) to electrical supply terminals (36) that the electrically controlled injection actuator (12) has, said profile (22) being provided to impose on the injector needle (10) a filling lift law (23) from which follows, on the one hand, the temporal evolution of the position of said needle (10) relative to that of the needle seat (11) with which it cooperates, and, on the other hand, a filling opening period (24) of the gaseous fuel mixture injector (9);
• Using a recovery variable (25) that sets the offset between, on the one hand, the crankshaft angular position (CA) at the time of ignition (41) of the pilot charge (39) in the ignition prechamber (2) by the spark plug (19), and, on the other hand, the crankshaft angular position (CA) at the time of resting the injector needle (10) on the needle seat (11) with which it cooperates;
• Using a triggering variable of the filling electrical current profile (26) that sets, according to the recovery variable (25), the crankshaft angular position (CA) from which the computer (13) applies the filling electrical current profile (22) to the electrical supply terminals (36) of the electrically controlled injection actuator (12), said triggering variable (26) being calculated by said computer (13), on the one hand, from the crankshaft angular position (CA) from which the ignition (41) of the pilot charge (39) in the ignition prechamber (2) is triggered by the computer (13), and, on the other hand, from the filling opening period (24) of the gaseous fuel mixture injector (9) that is imposed by the filling electrical current profile (22);
• Using a richness variable (27) which sets the mass proportion of oxidiser (15) and fuel (16) which make up the gaseous fuel mixture (14) constituting the pilot charge (39) produced by the oxidiser-fuel mixer (18);
• Generating for each operating point of the engine (4) an injection data set (28) which comprises a filling electrical current profile (22), a value assigned to the recovery variable (25), a value assigned to the triggering variable of the filling current profile (26), and a value assigned to the richness variable (27), said set (28) setting the quantity, the composition and the turbulence of the gaseous fuel mixture (14) constituting the pilot charge (39) at the time of ignition (41) of said mixture (14), which determines the rate of combustion of said mixture (14) in the ignition prechamber (2), on the one hand, and the heat power released by said combustion, on the other hand;
• Running the injection data set (28) corresponding to the operating point of the internal combustion engine (4).