Direct-injection spark-ignition internal combustion engine

1. A direct-injection spark-ignition internal combustion engine, comprising:

an injector fitted to an upper wall of a combustion chamber, in a central area thereof, for injecting fuel directly into the combustion chamber,

an ignition plug provided with an electrode part positioned within or near a fuel injection area in which fuel injected by the injector spreads,

a cavity formed in a top face of a piston to guide fuel injected by the injector to near the electrode part of the ignition plug,

operational status detection means for detecting operational status of the internal combustion engine indicative of a steady operation state of the internal combustion engine, and

ignition timing control means for controlling ignition timing for the ignition plug, wherein

the ignition timing control means controls the ignition timing, depending on the operational status detected by the operational status detection means, such that ignition is carried out at least either during or immediately after fuel injection by the injector, or at the time when fuel injected by the injector arrives near the electrode part by being guided by the cavity.

2. The direct-injection spark-ignition internal combustion engine according to claim 1 , wherein

the ignition timing control means controls the ignition timing such that, when a non-steady operation state of the internal combustion engine is detected by the operational status detection means, ignition is carried out by the ignition plug during or immediately after fuel injection by the injector.

3. The direct-injection spark-ignition internal combustion engine according to claim 1 , further comprising:

misfire detection means for detecting misfire occurring within the combustion chamber, wherein

the ignition timing control means controls the ignition timing such that ignition is carried out during or immediately after fuel injection by the injector, and if the misfire detection means detects misfire at the time of this ignition, ignition is also carried out at the time when an air-fuel mixture formed by more vaporized fuel arrives near the electrode part by being guided by the cavity.

4. The direct-injection spark-ignition internal combustion engine according to claim 1 , wherein,

the ignition timing control means controls the ignition timing such that whenever ignition is carried out during or immediately after fuel injection by the injector, ignition is also carried out at the time when an air-fuel mixture formed by fuel injected by the injector and more vaporized arrives near the electrode part by being guided by the cavity.

5. The direct-injection spark-ignition internal combustion engine according to claim 1 , wherein,

the operational status detection means determines that the internal combustion engine is in the steady operation state when at least one of a change in an engine speed, a change in a vehicle speed, and a change in a throttle opening is within a predetermined value.

6. The direct-injection spark-ignition internal combustion engine according to claim 5 , wherein,

the operational status detection means determines that the internal combustion engine is in the steady operation state when the in the engine speed is within a first predetermined value, the change in the vehicle speed is within a second predetermined value, and the change in the throttle opening is within a third predetermined value.

7. A direct-injection spark-ignition internal combustion engine, comprising:

an injector fitted to an upper wall of a combustion chamber, in a central area thereof, for injecting fuel directly into the combustion chamber,

an ignition plug provided with an electrode part positioned within or near a fuel injection area in which fuel injected by the injector spreads,

a cavity formed in a top face of a piston to guide fuel injected by the injector to near the electrode part of the ignition plug,

an exhaust catalytic converter provided in an exhaust path connected with the combustion chamber, for converting harmful substances contained in exhaust gas flowing through the exhaust path,

catalyst temperature detection means for detecting temperature of the exhaust catalytic converter,

operational status detection means for detecting operational status of the internal combustion engine indicative of a steady operation state of the internal combustion engine;

injection timing control means for controlling injection timing for the injector, and

ignition timing control means for controlling ignition timing for the ignition plug, wherein

the injection timing control means and the ignition timing control means selects between a first operation mode in which ignition is carried out during or immediately after fuel injection by the injector and a second operation mode in which ignition is carried out at the time when fuel injected by the injector arrives near the electrode part by being guided by the cavity, depending on the temperature of the exhaust catalytic converter detected by the catalyst temperature detection means when the steady operation state of the internal combustion engine is detected by the operational status detection means.

8. The direct-injection spark-ignition internal combustion engine according to claim 7 , wherein

when the temperature of the exhaust catalytic converter detected by the catalyst temperature detection means is equal to or lower than a first specified temperature, the injection timing control means and the ignition timing control means choose the operation mode in which ignition is carried out at the time when fuel injected by the injector arrives near the electrode part by being guided by the cavity.

9. The direct-injection spark-ignition internal combustion engine according to claim 8 , wherein

when the temperature of the exhaust catalytic converter detected by the catalyst temperature detection means is equal to or higher than a second specified temperature which is higher than the first specified temperature, the injection timing control means and the ignition timing control means choose the operation mode in which ignition is carried out during or immediately after fuel injection by the injector.

10. The direct-injection spark-ignition internal combustion engine according to claim 7 , further comprising:

misfire detection means for detecting misfire occurring within the combustion chamber, wherein

the ignition timing control means controls the ignition timing such that ignition is carried out during or immediately after fuel injection by the injector, and if the misfire detection means detects misfire at the time of this ignition, ignition is also carried out at the time when an air-fuel mixture formed by more vaporized fuel arrives near the electrode part by being guided by the cavity.

11. The direct-injection spark-ignition internal combustion engine according to claim 7 , wherein

the ignition timing control means controls the ignition timing such that whenever ignition is carried out during or immediately after fuel injection by the injector, ignition is also carried out at the time when an air-fuel mixture formed by fuel injected by the injector and more vaporized arrives near the electrode part by being guided by the cavity.

12. The direct-injection spark-ignition internal combustion engine according to claim 7 ,

wherein when the temperature of the exhaust catalytic converter detected by the catalyst temperature detection means is between the first specified temperature and the second specified temperature, the ignition timing control means and the ignition timing control means selects between the first operation mode and the second operation mode based on an engine speed and an engine load.