Ignition time controller, ignition time control method and engine control unit for internal combustion engine

An ignition time controller for an internal combustion engine equipped with a cam phase changing mechanism for changing a cam phase with respect to a crank shaft for at least one of an intake cam for opening/closing an intake valve and an exhaust cam for opening/closing an exhaust valve such that the cam phase reaches a target cam phase so that said engine is operated in a combustion mode switched between a uniform combustion mode in which a fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which a fuel is injected into a cylinder in a compression stroke, said ignition time controller comprising:

• an engine rotational speed detecting module for detecting a rotational speed of said internal combustion engine;
• an accelerator pedal opening detecting module for detecting an opening of an accelerator pedal;
• a required torque determining module for determining a required torque outputted by said internal combustion engine based on the detected engine rotational speed and accelerator pedal opening;
• a fuel injection time determining module for determining a time at which a fuel is injected into said cylinder;
• a basic ignition time determining module for determining a basic ignition time based on said engine rotational speed and said determined required torque when said engine is in said uniform combustion mode, and for determining the basic ignition time based on said engine rotational speed and said determined fuel injection time when said engine is in said stratified combustion mode;
• an actual cam phase detecting module for detecting an actual cam phase;
• and
• an ignition time correcting module for correcting said basic ignition time in accordance with a cam phase deviation which is a difference between the detected actual cam phase and said target cam phase.

An ignition time control method for an internal combustion engine equipped with a cam phase changing mechanism for changing a cam phase with respect to a crank shaft for at least one of an intake cam for opening/closing an intake valve and an exhaust cam for opening/closing an exhaust valve such that the cam phase reaches a target cam phase so that said engine is operated in a combustion mode switched between a uniform combustion mode in which a fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which a fuel is injected into a cylinder in a compression stroke, said method comprising the steps of:

• detecting a rotational speed of said internal combustion engine;
• detecting an opening of an accelerator pedal;
• determining a required torque outputted by said internal combustion engine based on the detected engine rotational speed and accelerator pedal opening;
• determining a time at which a fuel is injected into said cylinder;
• determining a basic ignition time based on said engine rotational speed and said determined required torque when said engine is in said uniform combustion mode, and determining the basic ignition time based on said engine rotational speed and said determined fuel injection time when said engine is in said stratified combustion mode;
• detecting an actual cam phase;
• and
• correcting said basic ignition time in accordance with a cam phase deviation which is a difference between the detected actual cam phase and said target cam phase.

An engine control unit including a control program for causing a computer to carry out ignition time control for an internal combustion engine equipped with a cam phase changing mechanism for changing a cam phase with respect to a crank shaft for at least one of an intake cam for opening/closing an intake valve and an exhaust cam for opening/closing an exhaust valve such that the cam phase reaches a target cam phase so that said engine is operated in a combustion mode switched between a uniform combustion mode in which a fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which a fuel is injected into a cylinder in a compression stroke,

• wherein said control program causes said computer to detect a rotational speed of said internal combustion engine;
• detect an opening of an accelerator pedal;
• determine a required torque outputted by said internal combustion engine based on the detected engine rotational speed and accelerator pedal opening;
• determine a time at which a fuel is injected into said cylinder;
• determine a basic ignition time based on said engine rotational speed and said determined required torque when said engine is in said uniform combustion mode, and determining the basic ignition time based on said engine rotational speed and said determined fuel injection time when said engine is in said stratified combustion mode;
• detect an actual cam phase;
• and correct said basic ignition time in accordance with a cam phase deviation which is a difference between the detected actual cam phase and said target cam phase.