Cylinder injection engine and control apparatus and method thereof

A cylinder injection engine comprising:

• a fuel injector for injecting a fuel into a combustion chamber formed between a cylinder head and a piston;
• an intake port opening to said combustion chamber;
• an intake valve engaging with said intake port;
• a plurality of spark plugs provided for each cylinder for effecting ignition of a mixture formed within said combustion chamber;
• an external EGR valve having a function of EGR amount control to said cylinder;
• a gas flow control valve;
• and
• means for setting air/fuel ratio modes and for setting mode of switching spark plugs,
• wherein said air/fuel ratio mode setting means includes at least a stratified charge lean combustion mode concentrating the mixture around the spark plug, a stoichiometric mode for forming a homogenous mixture and a homogenous lean combustion mode, and the engine has two intake valves in each cylinder, a fuel injector forming fuel spray in two directions is arranged between said two intake valves, spark plugs are arranged in the vicinity of intake valves in each cylinder, a tumble control valve is employed as a air flow control means for controlling said tumble control valve in closing direction under stratified charge combustion operation for strengthen tumble for concentrate the fuel injected in the compression stroke in the vicinity of two spark plugs by the tumble flow.

A cylinder injection engine comprising:

• a fuel injector for injecting a fuel into a combustion chamber formed between a cylinder head and a piston;
• an intake port opening to said combustion chamber;
• an intake valve engaging with said intake port;
• a plurality of spark plugs provided for each cylinder for effecting ignition of a mixture formed within said combustion chamber;
• an external EGR valve having a function of EGR amount control to said cylinder;
• a gas flow control valve;
• and
• means for setting air/fuel ratio modes and for setting mode of switching spark plugs,
• wherein said air/fuel ratio mode setting means includes at least a stratified charge lean combustion mode concentrating the mixture around the spark plug, a stoichiometric mode for forming a homogenous mixture and a homogenous lean combustion mode, and said fuel injector is arranged at the top of the combustion chamber, said spark plugs are arranged in the vicinity of said fuel injector, a swirl control valve is employed as a air flow control means for controlling said swirl control valve in closing direction under stratified charge combustion operation for strengthen swirl for concentrate the injected fuel in the vicinity of the spark plugs.

A cylinder injection engine comprising:

• a fuel injector for injecting a fuel into a combustion chamber formed between a cylinder head and a piston;
• an intake port opening to said combustion chamber;
• an intake valve engaging with said intake port;
• a plurality of spark plugs provided for each cylinder for effecting ignition of a mixture formed within said combustion chamber;
• an external EGR valve having a function of EGR amount control to said cylinder;
• a gas flow control valve;
• and
• means for setting air/fuel ratio modes and for setting mode of switching spark plugs, wherein said air/fuel ratio mode setting means includes at least a stratified charge lean combustion mode concentrating the mixture around the spark plug, a stoichiometric mode for forming a homogenous mixture and a homogenous lean combustion mode, and two intake valves are provided in each cylinder, said fuel injector is arranged on the side of intake port of the cylinder, two spark plugs are respectively arranged in the vicinity of respective intake values, a swirl control valve is employed as a air flow control means for controlling said swirl control valve in closing direction under stratified charge combustion operation for strengthen swirl for concentrate the injected fuel in the vicinity of one of the spark plugs.

A cylinder injection engine comprising:

• a fuel injector for injecting a fuel into a combustion chamber formed between a cylinder head and a piston;
• an intake port opening to said combustion chamber;
• an intake valve engaging with said intake port;
• a plurality of spark plugs provided for each cylinder for effecting ignition of a mixture formed within said combustion chamber;
• an external EGR valve having a function of EGR amount control to said cylinder;
• a gas flow control valve;
• and
• means for setting air/fuel ratio modes and for setting mode of switching spark plugs, wherein said air/fuel ratio mode setting means further includes a compression ignition mode, said air/fuel ratio mode setting means includes at least a stratified charge lean combustion mode concentrating the mixture around the spark plug, a stoichiometric mode for forming a homogenous mixture and a homogenous lean combustion mode, and in compression ignition mode, an interval of rich spikes is set to be longer than that in stratified charge lean combustion operation.

A cylinder injection engine comprising:

• a fuel injector for injecting a fuel into a combustion chamber formed between a cylinder head and a piston;
• an intake port opening to said combustion chamber;
• an intake valve engaging with said intake port;
• a plurality of spark plugs provided for each cylinder for effecting ignition of a mixture formed within said combustion chamber;
• an external EGR valve having a function of EGR amount control to said cylinder;
• a gas flow control valve;
• and
• means for setting air/fuel ratio modes and for setting mode of switching spark plugs, wherein said air/fuel ratio mode setting means further includes a compression ignition mode, and said air/fuel ratio mode setting means includes at least a stratified charge lean combustion mode concentrating the mixture around the spark plug, a stoichiometric mode for forming a homogenous mixture and a homogenous lean combustion mode, upon a rich spike fuel injection is performed at stoichiometric air/fuel ratio or rich air/fuel ratio for spark ignition in intake stroke.

A cylinder injection engine comprising:

• air flow control means for controlling air flow in a cylinder;
• EGR amount control means;
• a plurality of ignition means per each cylinder;
• at low load condition of the engine, stratified charge combustion is performed by said air flow control means and ignition is performed by one of spark plugs of said ignition means for combustion, and
• at high load condition of the engine, homogeneous combustion using said EGR amount control means is performed and ignition is performed by at least two spark plugs for combustion.