Internal combustion engine with dual induction system

In an internal combustion engine, means defining a cylinder having an axis, a piston, slidably disposed in said cylinder to define a variable volume combustion chamber, a dual induction system for said engine, said system comprising:

• a primary induction passage leading from the atmosphere to a first valve controlled inlet port for said combustion chamber, said primary induction passage and said first inlet port being so constructed and arranged as to operatively restrict the flow of air therethrough and introduce the air flowing therethrough into said combustion chamber at a high velocity in a direction tangential with respect to the wall of said cylinder whereby the so introduced air thereafter swirls around said axis of said cylinder;
• a fixed venturi disposed at the upstream end of said primary induction passage;
• a first throttle valve operatively disposed in said primary induction passage downstream of said venturi;
• a secondary induction passage leading from the atmosphere to a second valve controlled inlet port for said combustion chamber, said secondary induction passage and said second inlet port being so constructed and arranged as to have a lower restriction to the flow of air therethrough than said primary induction passage and first inlet port, and to introduce the air flowing therethrough into said combustion chamber at a lower velocity and in larger quantities than said primary induction passage and first inlet port and in a direction which slows the swirling of the air from said primary induction passage around said axis;
• a second throttle valve operatively disposed in said second induction passage;
• a pressure differential responsive motor fluidly connected with said venturi and operatively connected to said second throttle valve for moving same in response to the degree of vacuum prevailing at said venturi;
• and,
• means for introducing fuel into said secondary induction passage to form an air-fuel mixture richer than the one formed in said primary induction passage.

A method of operating an internal combustion engine, comprising the steps of:

• inducting air through a primary induction passage which restricts the flow of air therethrough thus increasing the velocity of the air flowing therein;
• introducing the high velocity air into a combustion chamber of said engine via a first inlet port in a direction tangential with respect to the wall of a cylinder which forms part of said combustion chamber thus inducing the air to swirl in said combustion chamber about the axis of said cylinder;
• sensing the vacuum prevailing at a fixed venturi formed in said primary induction passage;
• throttling a secondary induction passage which has a lower restriction to the flow of air therein than said primary induction passage in accordance with the vacuum sensed;
• inducting air through said secondary induction passage at a lower velocity and in larger quantities than that inducted through said primary induction passage;
• introducing the air from said secondary induction passage into said combustion chamber via a second inlet port;
• slowing the swirl of the air from said primary induction passage about said axis via introducing the air from said secondary induction passage;
• and,
• introducing fuel into said primary and secondary induction passages to form a lean air fuel mixture in said primary induction passage and a richer than the aforesaid lean air fuel mixture in said secondary induction passage.