US 5,398,653 A · Internal combustion engine

Abstract

An internal combustion engine has first and second cylinders (12, 14), the first cylinder (12) having a larger swept volume than the second cylinder (14) and the second cylinder being formed in the crown of the first cylinder. First and second pistons (16, 18) are reciprocable respectively in the first and second cylinders (12, 14), the second piston (18) being formed as a protrusion on the crown of the first piston (16). The first cylinder has an air inlet (25) and an exhaust outlet (27) whilst a first fuel source (34) provides fuel to the second cylinder (14). The second piston has a crown (35) which is spaced from and connected to the crown (36) of the first piston and which has an edge (37) which is relatively thin in the axial direction compared to the spacing of the first piston crown from the second piston crown. This defines a combustion space (20) between the piston crowns and a side wall (14a) of the second cylinder (14) when the pistons are substantially at the inner dead center position. The combustion space (20) communicates with both cylinders (12,14) during part of the expansion stroke. A spark plug (52) is provided communicating with the combustion space. The ignition process is started with a spark and allowed to continue by compression ignition. After the spark ignition process begins, the flame raises the pressure and temperature of the gas in the combustion space sufficiently to cause compression-ignition of the remainder of the vaporized fuel as it ingresses into the combustion space under the action of the smaller piston and mixes with more air.

Claims33

Dependent claims

An internal combustion engine comprising:

at least one set of first and second cylinders, said first cylinder having a larger swept volume than said second cylinder;
respective first and second pistons movable in said first and second cylinders;
air inlet means communicating with said first cylinder;
exhaust means communicating with said first cylinder;
a first fuel source for providing fuel to said second cylinder;
means defining a combustion space when said first and second pistons are substantially at an inner dead centre position, said combustion space communicating with both said first and second cylinders during an expansion stroke of said first and second pistons;
ignition means communicating with said combustion space;
inhibiting means for inhibiting ingression of fuel/air mixture from said second cylinder into said combustion space prior to said second piston reaching a preselected point in a compression stroke;
control means for triggering said ignition means to discharge ignition energy into said combustion space after commencement of said ingression and prior to completion of said ingression to ignite a portion of ingressing fuel thereby to raise temperature and pressure in said combustion space to levels sufficient to ignite a remainder of said fuel by compression ignition;
and means for ensuring that said pressure and temperature reached in said combustion space near an end of said compression stroke are insufficient to cause spontaneous compression ignition of fuel used.

7 more elements

A method of operating an internal combustion engine wherein the engine has:

at least one set of first and second cylinders, said first cylinder having a larger swept volume than said second cylinder;
respective first and second pistons movable in said first and second cylinders;
air inlet means communicating with said first cylinder;
exhaust means communicating with said first cylinder;
a first fuel source for providing fuel to said second cylinder;
means defining a combustion space when said first and second pistons are substantially at an inner dead centre position, said combustion space communicating with both said first and second cylinders during an expansion stroke of said first and second pistons;
ignition means communicating with said combustion space;
inhibiting means for inhibiting ingression of fuel/air mixture from said second cylinder into said combustion space prior to said second piston reaching a preselected point in a compression stroke;
control means for triggering said ignition means;
and means for ensuring that a pressure and temperature reached in said combustion space near an end of said compression stroke are insufficient to cause spontaneous compression ignition of fuel used;
wherein the method comprises:
introducing a first preselected quantity of fuel into said second cylinder during an induction and/or said compression stroke of said engine;
and discharging ignition energy into said combustion space after commencement of Said ingression and prior to completion of said ingression to ignite a portion of ingressing fuel thereby to raise said temperature and pressure in paid combustion space to levels sufficient to ignite a remainder of said fuel by compression ignition.

10 more elements

Dependencies are inferred from the claim text.

Internal combustion engine

Life of this patent

Internal combustion engine

Life of this patent

Abstract

Claims33