An engine includes: an engine main body including a plurality of cylinders; a plurality of exhaust pipes connected to exhaust sides of the plurality of cylinders; a plurality of throttle valves positioned on intake sides of the plurality of cylinders; a catalyst device connected to the plurality of exhaust pipes; and a controller configured to control opening and/or closing operations of the plurality of throttle valves. One of the exhaust pipes is formed shorter than other exhaust pipe. And the controller opens one of the throttle valves upstream of the one of the exhaust pipes at a higher speed or a larger opening degree than other throttle valve upstream of the other exhaust pipe when the engine is started.

Cross-port air flow that improves engine fuel economy and reduces pumping losses during part-throttle operation can be implemented in various types of internal combustion engine systems using ports that interconnect the intake ports of different cylinders, thus allowing different cylinders to share combustion air. Cross-port air flow is commenced during part-throttle engine operation to disrupt the primary combustion air flow from each throttle to its associated cylinder, which reduces charge density and engine power. The engine compensates for the reduced power by incrementally opening the throttles, thus increasing the primary combustion air flow, reducing pumping losses and improving fuel economy.

A mixture formation unit has a base body in which an intake channel section is formed. The intake channel section extends from a first end side of the base body to a second end side of the base body. The mixture formation unit has at least one rectilinearly extending channel which opens into the intake channel section. The channel opens at the first end side of the base body. The mixture formation unit is preferably provided for a two stroke engine whose intake channel is divided downstream of the mixture formation unit into a mixture channel and an air channel.

A throttle control method of controlling an opening degree of a throttle valve in a multi-cylinder engine that includes throttle valves in intake passages provided for each cylinder. It is possible to independently control the opening degree for each of the throttle valves. The throttle control method includes controlling the opening degree of the throttle valve is based on differences among intake air amounts in the respective intake passages.

Cross-port air flow that improves engine fuel economy and reduces pumping losses during part-throttle operation can be implemented in various types of internal combustion engine systems using ports that interconnect the intake ports of different cylinders, thus allowing different cylinders to share combustion air. Cross-port air flow is commenced during part-throttle engine operation to disrupt the primary combustion air flow from each throttle to its associated cylinder, which reduces charge density and engine power. The engine compensates for the reduced power by incrementally opening the throttles, thus increasing the primary combustion air flow, reducing pumping losses and improving fuel economy.

A throttle body fuel injection system including a throttle body with at least one air intake, a fuel injector coupled to the throttle body at a fuel port and an annular ring coupled to the cylindrical inner wall of the air intake. The annular ring includes a primary fuel discharge orifice adjacent to the fuel port and a plurality of secondary fuel discharge orifices arranged radially around the annular ring for spraying atomized fuel into the air intake.

A first throttle body and a second throttle body include valve rotation devices that independently drive respective throttle valves. The first throttle body and the second throttle body are arranged such that the respective valve rotation devices have states rotated around respective bore central axes to cause respective throttle valve rotation shafts to have angles with respect to straight lines parallel to a crankshaft in an engine top view.

A throttle body fuel injection system including a throttle body with at least one air intake, a fuel injector coupled to the throttle body at a fuel port and an annular ring coupled to the cylindrical inner wall of the air intake. The annular ring includes a primary fuel discharge orifice adjacent to the fuel port and a plurality of secondary fuel discharge orifices arranged radially around the annular ring for spraying atomized fuel into the air intake.

A throttle control method of controlling an opening degree of a throttle valve in a multi-cylinder engine that includes throttle valves in intake passages provided for each cylinder. It is possible to independently control the opening degree for each of the throttle valves. The throttle control method includes controlling the opening degree of the throttle valve is based on differences among intake air amounts in the respective intake passages.

This diesel engine (10) has an engine body (11), an EGR device (12), and a control unit (13). The engine body (11) has combustion chambers (15) and injectors (16). The EGR device (12) is provided with: a gas flow path (35) that returns a portion of exhaust gas from the combustion chambers (15) to an intake flow path (17); and an EGR device (37) that has a butterfly valve (42). When the butterfly valve (42) is set to a rotation angle position of 0 when in a closed posture (42A), the control unit (13) drives the butterfly valve (42) within a first rotation angle range of no less than 0 when the injection amount of fuel to be injected by the injectors (16) is no less than a predetermined threshold, and the control unit (13) drives the butterfly valve (42) within a second rotation angle range that passes through 0 when the injection amount is less than the threshold. The threshold is a value greater than zero.