Internal combustion engine and a process for its operation

In a four-cycle internal combustion engine having at least one cylinder, a piston disposed for reciprocation in the cylinder, a unitary combustion chamber defined by the top of the piston and the cylinder when the piston is at approximately its uppermost position therein, a spark plug for initiating combustion in the combustion chamber, an inlet valve for admitting fuel and air into the combustion chamber, and an exhaust valve for exhausting products of combustion from the combustion chamber, an improvement for each cylinder which comprises:

• a. induction channel means serially communicating atmosphere with the combustion chamber through the inlet valve for supplying the cylinder with fuel and air;
• b. means for injecting fuel into the induction channel means in a zone upstream from the inlet valve during the time between inlet valve openings to develop a fuel-rich combustible cloud in the induction channel means, the injection means injecting an amount of fuel which effects an air-to-fuel ratio in the combustion chamber determined on the basis of a homogeneous charge and just prior to the occurrence of spark which is too lean to burn;
• c. a space in the induction channel means between the zone where the fuel-rich cloud is formed and the spark plug forming a cloud free zone without combustible gases and for assuming presence of the fuel-rich cloud at the spark plug at spark;
• d. the induction channel means and the cylinder having a configuration to avoid substantial dissipation of the cloud during the formation and subsequent induction of the cloud into the combustion chamber and during the time that the cloud is in the combustion chamber at least until spark occurs so that just prior to the occurrence of spark a heterogeneous charge is in the combustion chamber defined, relative to stoichiometric, by a fuel-rich cloud and a fuel lean zone of gases outside the cloud, the injection means effecting the injection of an amount of fuel which gives an overall fuel-to-air ratio on the combustion chamber that would be too lean to burn;
• and
• e. means for varying the power of the engine without throttling intake air.

In a four-cycle, spark ignition, reciprocating internal combustion engine having at least one cylinder, a piston disposed for reciprocation in the cylinder, an inlet and an exhaust valve for the cylinder, a unitary combustion chamber in the cylinder, and a spark plug for igniting a charge of fuel and air in the combustion chamber, an improvement in the induction system for each cylinder which comprises:

• a. induction pipe means serially communicating atmosphere with the combustion chamber through the inlet valve;
• b. means for injecting fuel into the induction pipe in a fuel injection zone during the time that the inlet valve is closed to form a combustible cloud in the zone, the induction pipe means providing a space for a cloud free zone for air between the zone of cloud formation and the spark plug;
• c. the space between the fuel injection zone and the spark plug being such that the cloud will be inducted into the cylinder with air serially ahead of it during the time that the inlet valve is open and be at the spark plug when spark occurs;
• d. the induction pipe means and the cylinder preventing substantial dissipation of the cloud during the cloud's formation, induction into the cylinder and arrival at the spark plug when spark occurs;
• e. means for varying the fuel-to-air ratio between a predetermined richness and a predetermined leanness by varying the quantity of fuel injected into the induction pipe means, the predetermined lean fuel-to-air ratio corresponding to a power output above no load operation;
• and
• f. means for retarding the spark for power outputs between no load and the power output corresponding to the predetermined lean fuel-to-air ratio.

A method of operating a reciprocating, spark ignition internal combustion engine comprising the steps of:

• a. forming a combustible cloud of fuel in the induction channel of each cylinder of the engine upstream from the inlet valve to the cylinder and upstream from air in the channel during the time between openings of the inlet valve, the cloud being fuel-rich relative to stoichiometric;
• b. inducting air and the cloud of fuel into a unitary combustion chamber in the cylinder such that the cloud is at a spark plug in the combustion chamber and the air is in a zone outside the cloud when spark occurs;
• c. igniting the cloud with the spark;
• d. initiating burning of fuel in the cloud;
• and
• e. substantially completing burning of the fuel in the zone containing the air.