Method and apparatus using proportional residual gas storage to reduce NO.sub.x emissions from internal combustion engines

In a four-cycle spark-ignition internal combustion reciprocating piston engine having a main combustion chamber with a valved intake passage for a lean mixture, an auxiliary combustion chamber with a valved intake passage for a rich mixture, and a torch nozzle connecting said chambers, the improvement for minimizing NO.sub.x in the engine exhaust gases comprising, in combination:

• a residual gas chamber having a restricted opening communicating with the auxiliary chamber and having an end wall remote from said opening, a spark plug having electrodes forming a spark gap positioned in said residual gas chamber, the volumes of the chambers being related as follows:
• ##EQU2## where:
• V.sub.a = volume of auxiliary chamber
• V.sub.rg = volume of residual gas chamber
• V.sub.m = volume of main chamber at top dead center.

In a four-cycle spark-ignition internal combustion reciprocating piston engine having a main combustion chamber with a valved intake passage for a lean mixture, an auxiliary combustion chamber with a valved intake passage for a rich mixture, and a torch nozzle connecting said chambers, the improvement for minimizing NO.sub.x in the engine exhaust gases comprising, in combination:

• a residual gas chamber having a restricted opening communicating with the auxiliary chamber and having an end wall remote from said opening, a spark plug having electrodes forming a spark gap positioned in said residual gas chamber, the volumes of the auxiliary chamber and the residual gas chamber being related as follows:
• ##EQU3## where:
• V.sub.a = volume of auxiliary chamber
• V.sub.rg = volume of residual gas chamber.

In a four-cycle spark-ignition internal combustion reciprocating piston engine having a main combustion chamber with a valved intake passage for a lean mixture, an auxiliary combustion chamber with a valved intake passage for a rich mixture, and a torch nozzle connecting said chambers, the improvement for minimizing NO.sub.x in the engine exhaust gases comprising, in combination:

• a residual gas chamber having a restricted opening communicating with the auxiliary chamber and having an end wall remote from said opening, a spark plug having electrodes forming a spark gap positioned in said residual gas chamber, the cross section area of the torch nozzle being related to the volumes of the residual gas chamber and auxiliary chamber as follows:
• ##EQU4## where:
• F.sub.t = area of torch nozzle
• V.sub.rg = volume of residual gas chamber
• V.sub.a = volume of auxiliary chamber.

In a four-cycle spark-ignition internal combustion reciprocating piston engine having a main combustion chamber with a valved intake passage for a lean mixture, an auxiliary combustion chamber with a valved intake passage for a rich mixture, and a torch nozzle connecting said chambers, the improvement for minimizing NO.sub.x in the engine exhaust gases comprising, in combination:

• a residual gas chamber having a restricted opening communicating with the auxiliary chamber and having an end wall remote from said opening, a spark plug having electrodes forming a spark gap positioned in said residual gas chamber, the area of the restricted opening as compared to the volume of the residual gas chamber being as follows;
• ##EQU5## where;
• F.sub.rg = area of restricted opening
• V.sub.rg = volume of residual gas chamber.

In a four-cycle spark-ignition internal combustion reciprocating piston engine, the combination of:

• a main combustion chamber with an intake passage for a lean mixture, an auxiliary combustion chamber having an intake passage for a rich mixture, a torch nozzle restriction connecting said chambers, mechanically operated valves movable in timed sequence for controlling flow through said intake passages, a residual gas chamber having a restricted opening at one end communicating with the auxiliary chamber and having an end wall remote from said opening, a spark plug having electrodes forming a spark gap positioned in said residual gas chamber nearer to the restricted opening than to said end wall, the position of said restricted opening with respect to the auxiliary chamber being such that the suction stroke of the piston serving to draw a rich mixture into and through the auxiliary chamber and through the torch nozzle restriction into the main chamber does not substantially change the contents of the residual gas chamber which comprise residual burned gas from the previous combustion cycle of the engine, the restricted opening serving to promote mixing of rich mixture and residual gas in said residual gas chamber during the compression stroke of the piston, whereby at the time of ignition, the concentration of residual gas near said end wall of said residual gas chamber is greater than in the region containing said spark gap.

For use with a four-cylinder spark-ignition internal combustion reciprocating engine having an auxiliary combustion chamber connected through a torch nozzle with a main combustion chamber, the improvement comprising:

• means forming a residual gas chamber having a restricted opening at one end, means for securing said gas chamber to the engine to establish communication with the auxiliary chamber through said restricted opening, said chamber having a wall remote from said opening, means on said chamber for connection with a spark plug so that the spark gap defined by the spark plug electrodes is positioned within the residual gas chamber nearer to the restricted opening than to said wall, the position of said restricted opening with respect to the auxiliary chamber being such that the suction stroke of the piston serving to draw a rich mixture into and through the auxiliary chamber and through the torch nozzle restriction into the main chamber does not substantially change the contents of the residual gas chamber which comprise residual burned gas from the previous combustion cycle of the engine, the restricted opening serving to promote mixing of rich mixture and residual gas in said residual gas chamber during the compression stroke of the piston, whereby at the time of ignition, the concentration of residual gas near said wall of said residual gas chamber is greater than in the region containing said spark gap.

In a four-cycle spark-ignition internal combustion reciprocating piston engine for minimizing emissions of NO.sub.x in the engine exhaust gases, the combination of:

• a main combustion chamber having a valved intake passage for a lean mixture, an auxiliary combustion chamber having a valved intake passage for a rich mixture, means forming a torch nozzle restriction connecting said chambers, means forming a residual gas chamber having a restricted opening at one end communicating with said auxiliary chamber, and having an end wall remote from the restricted opening, the total volume of the auxiliary chamber and residual gas chamber being from 5 to 30% of the total combined volume of all three chambers, the suction stroke of the piston serving to draw a lean mixture into the main chamber and a rich mixture into and through the auxiliary chamber and torch nozzle restriction into the main chamber without materially affecting the contents of the residual gas chamber, the shape of the residual gas chamber and the position of the restricted opening acting to promote mixing so that after the compression stroke of the piston the concentration of residual gas from the previous combustion cycle of the engine mixed with rich mixture is greater near said end wall of the residual gas chamber than near said restricted opening, sparking means in said residual gas chamber positioned nearer to said restricted opening than to said end wall for igniting the mixture therein whereby a first flame is caused to extend through the restricted opening to produce turbulent ignition in the auxiliary chamber, thereby causing a second flame to extend through the torch nozzle restriction and into the main chamber.