One embodiment of the invention relates to an internal combustion engine including an engine block having a first cylinder and a second cylinder, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an air filter assembly, a first electric fan coupled to a first duct, and a second electric fan coupled to a second duct. The first duct is configured to direct cooling air directly over the first cylinder. The second duct is configured to direct cooling air directly over the second cylinder. The first cylinder is at least partially within the first duct. The second cylinder is at least partially within the second duct.

A split-cycle engine includes: a first cylinder housing a first piston, wherein the first piston performs an intake stroke and a compression stroke, but does not perform an exhaust stroke; a second cylinder housing a second piston, wherein the second piston performs an expansion stroke and an exhaust stroke, but does not perform an intake stroke; and a valve chamber housing a valve, the valve comprising an internal chamber that selectively fluidly couples to the first and second cylinders, wherein the valve and internal chamber move within the valve chamber and relative to the first and second cylinders.

A heat management system for air-cooled engines suitable to power yard care equipment or vehicles. The system may generally comprise an engine, a blower configured to blow ambient cooling air across the engine, and an exhaust system comprising an exhaust header and a muffler. The exhaust header has an inlet end which receives heated exhaust gas from the engine and an outlet end fluidly coupled to the muffler. An air control baffle is configured to redirect a portion of the cooling air from the blower towards the exhaust header and the muffler to enhance cooling the exhaust system. The system may further include an outermost protective shield exposed to equipment operators and an inner heat barrier or shield located between the muffler and protective shield. The system is designed to ameliorate both radiative and convective sources of heat transfer to maintain the protective shield at temperatures below established industry standards.

A two-stroke engine comprises a first oiling system and a second oiling system. The first oiling system includes a low-pressure pump that distributes oil from a first oil tank to the two-stroke engine. The second oiling system includes a pump mechanically coupled to a crankshaft of the two-stroke engine, wherein the pump distributes oil from a second oil tank to an accessory at a pressure greater than the first oil pressure, wherein oil distributed to the accessory is returned to the second oil tank.

A small-air cooled internal combustion engine includes an engine block including a cylinder, a piston within the cylinder, a crankshaft configured to be driven by the piston, a blower system including a fan that is configured to pull air over the engine block, a fuel system for supplying an air-fuel mixture to the cylinder, and an exhaust system for removing exhaust from the cylinder. The exhaust system comprises an exhaust inlet, a muffler and, a catalytic converter including a catalyst. The catalyst comprises a precious metal loading having ruthenium as a primary element by mass.

The internal combustion engine includes a fan cover that covers a cooling fan driven by a crankshaft, a top cover that covers the fan cover, and a cooling air passage between the fan cover and the top cover. The fan cover includes a first rib facing the top cover in the cooling air passage.

One embodiment of the invention relates to an internal combustion engine including an engine block, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an electric fan, and an air filter assembly configured to filter incoming air from an air intake and provide cleaned air to a throttle body. The engine block includes a cylinder. The throttle body is configured to throttle incoming air to the cylinder.

Provided is a cover structure for an air-cooled engine to be cooled by cooling air generated by a cooling fan, the cover structure including: a fan housing covering the cooling fan and configured to guide the cooling air to a cylinder unit, the fan housing being formed with an opening part for maintenance of the cylinder unit; and a debris cover removably attached to the fan housing so as to close the opening part. The fan housing is formed with an air guide plate that constitutes a part of an outer periphery of the fan housing. The air guide plate includes a proximal end portion and a distal end portion extending from the proximal end portion to a cooling fin of the cylinder unit. A reinforcing plate for securing rigidity of the fan housing is formed at the proximal end portion of the air guide plate.

Provided is a cover structure for an air-cooled engine to be cooled by cooling air generated by a cooling fan, the cover structure including: a fan housing covering the cooling fan and configured to guide the cooling air to a cylinder unit, the fan housing being formed with an opening part for maintenance of the cylinder unit; and a debris cover removably attached to the fan housing so as to close the opening part. The fan housing is formed with an air guide plate that constitutes a part of an outer periphery of the fan housing. The air guide plate includes a proximal end portion and a distal end portion extending from the proximal end portion to a cooling fin of the cylinder unit. A reinforcing plate for securing rigidity of the fan housing is formed at the proximal end portion of the air guide plate.

A split-cycle engine includes: a first cylinder housing a first piston, wherein the first piston performs an intake stroke and a compression stroke, but does not perform an exhaust stroke; a second cylinder housing a second piston, wherein the second piston performs an expansion stroke and an exhaust stroke, but does not perform an intake stroke; and a valve chamber housing a valve, the valve comprising an internal chamber that selectively fluidly couples to the first and second cylinders, wherein the valve and internal chamber move within the valve chamber and relative to the first and second cylinders.