Caterpillar Inc.

D Ryan Williams

Scott Byron Fiveland

Ronald Graham Silver

An internal combustion engine operates on a six-stroke combustion cycle including a first compression stroke, a first power stroke, a second compression stroke, and a second power stroke. A first fuel charge is introduced to a combustion chamber of the engine at a first fuel rate during the first compression and/or first power stroke to produce lean exhaust gasses. A second fuel charge is also introduced to the combustion chamber during the second compression and/or second power stroke to normally produce lean exhaust gasses. Periodically, the second fuel charge can be increased to a second fuel rate to produce stoichiometric rich exhaust gasses. A lean nitrogen oxide trap can be disposed in an exhaust system associated with the engine to temporarily trap nitrogen oxides. Once saturated, the LNT can be periodically regenerated by production of the rich exhaust gasses.

After-treatment system and method for six-stroke combustion cycle

A six-stroke engine system including an engine with a combustion chamber including an exhaust valve that expels exhaust gasses during an exhaust stroke, and a blowdown exhaust valve that expels blowdown exhaust gasses during recompression. An intake line directs air into the combustion chamber, and an exhaust line directs exhaust gasses from combustion chamber. A blowdown exhaust line directs blowdown exhaust gasses out of the combustion chamber and into the intake line. The blowdown exhaust gasses are expelled through the blowdown exhaust valve during recompression, and exhaust gasses are expelled through the exhaust valve during the exhaust stroke.

Six-stroke engine system with blowdown exhaust recirculation

A six-stroke engine system including an engine with a combustion chamber including an exhaust valve that expels exhaust gasses, a blowdown exhaust valve that expel blowdown exhaust gasses during recompression, and an intake valve and a blowdown compressor intake valve that introduce air. An exhaust line directs exhaust gasses to drive a turbine, which drives a compressor. An intake line receives compressed air from the compressor and directs it into the combustion chamber through the intake valve. A blowdown exhaust line, separate from the exhaust line, directs blowdown exhaust gasses from the blowdown exhaust valve to drive the blowdown turbine, which drives a blowdown compressor. A blowdown compressor line directs compressed air from the intake line into the blowdown compressor, and directs super-compressed air from the blowdown compressor through the blowdown compressor intake valve during recompression.

Six-stroke engine system with blowdown turbocharger

An engine combustion cylinder is fluidly connectable to an intake system through an intake valve and to an exhaust system through an exhaust valve. A valve activation system is to activate the intake valve and the exhaust valve. The valve activation system is responsive to a controller providing command signals to the valve activation system such that, when the engine operates in a six-stroke combustion cycle, the intake valve is opened during a recompression stroke to allow a portion of the products from the first combustion stroke to exit the combustion cylinder and enter into the intake system. This may be done to match the power densities of the first and second power strokes of the piston.

Six-stroke engine power density matching system and method

A six-stroke engine system including an engine with a combustion chamber including an exhaust valve that expels exhaust gasses and a blowdown exhaust valve that expels blowdown exhaust gasses during recompression. An exhaust line communicates with the engine to direct exhaust gasses out of the combustion chamber, and a blowdown exhaust line communicates with the engine to direct blowdown exhaust gasses out of the combustion chamber and into the exhaust line. The blowdown exhaust gasses are expelled through the blowdown exhaust valve during the recompression stroke, and the exhaust gasses are expelled through the exhaust valve during the exhaust stroke.

Six-stroke engine system with blowdown exhaust system

An engine combustion cylinder is fluidly connectable to an intake system through an intake valve and to an exhaust system through an exhaust valve. A valve activation system is to activate the intake valve and the exhaust valve. The valve activation system is responsive to a controller providing command signals to the valve activation system such that, when the engine operates in a six-stroke combustion cycle, the intake valve is opened during a recompression stroke to allow a portion of the products from the first combustion stroke to exit the combustion cylinder and enter into the intake system.

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Edwards, IL, United States of America

D Ryan Williams