Engine control device

1. An engine control device for controlling an engine including a cylinder, the engine control device comprising:

a first fuel injection valve that injects a first amount of fuel that adheres to an inner peripheral wall of the cylinder;

a second fuel injection valve provided at such a position that a second amount of fuel, injected by the second fuel injection valve, adheres to the inner peripheral wall of the cylinder, the second amount of fuel being smaller than the first amount of fuel;

a cooling water temperature detector for detecting a temperature of cooling water for cooling the engine; and

an injection ratio determining arrangement for determining a ratio between an amount of fuel injected by the first fuel injection valve and an amount of fuel injected by the second fuel injection valve based on the temperature of cooling water detected by the cooling water temperature detector,

wherein the injection ratio determining arrangement stores an injection amount adjustment operation range in which the injection ratio determining arrangement is configured to increase a fuel injection ratio of the amount of fuel injected by the second fuel injection valve with respect to the amount of fuel injected by the first fuel injection valve, as the temperature of cooling water decreases, and

wherein the injection amount adjustment operation range is an operation range of the engine where a low-speed pre-ignition occurs.

2. The engine control device according to claim 1 , wherein the injection ratio determining arrangement is configured, in the injection amount adjustment operation range, to increase the fuel injection ratio as an engine load applied to the engine increases.

3. The engine control device according to claim 1 , wherein the injection amount adjustment operation range is a low-revolution, high-load operation range of the engine.

4. The engine control device according to claim 3 , wherein in the injection amount adjustment operation range, a threshold value of the engine load at which the fuel injection ratio is increased is reduced as the temperature of cooling water falls.

5. The engine control device according to claim 1 , wherein the first fuel injection valve comprises a direct injection valve configured to directly inject fuel into a combustion chamber, and

wherein the second fuel injection valve comprises a port injection valve configured to inject fuel into an intake passage leading to the combustion chamber.

6. The engine control device according to claim 1 , wherein the first fuel injection valve comprises a lateral side direct injection valve mounted to one of an inner peripheral wall of a combustion chamber and a peripheral edge portion of a top of the combustion chamber on a side of a cylinder head, and configured to directly inject fuel into the combustion chamber, and

wherein the second fuel injection valve comprises an overhead direct injection valve mounted to a center of the top of the combustion chamber on the side of the cylinder head, and configured to directly inject fuel into the combustion chamber.

7. The engine control device according to claim 1 , further comprising an injection timing determining arrangement for determining timings of fuel injection by the first fuel injection valve and the second fuel injection valve;

wherein the injection timing determining arrangement stores an injection timing adjustment operation range in which the injection timing determining arrangement is configured to advance the timing of fuel injection by the first fuel injection valve as the temperature of cooling water falls, when injecting fuel during an intake stroke.

8. The engine control device according to claim 7 , wherein the injection timing adjustment operation range is a low-revolution, high-load operation range of the engine, and

wherein in the injection timing adjustment operation range, a threshold value of the engine load at which the timing of fuel injection by the first fuel injection valve is advanced is reduced as the temperature of cooling water falls.

9. The engine control device according to claim 1 , further comprising an injection timing determining arrangement for determining timings of fuel injection by the first fuel injection valve and the second fuel injection valve;

wherein the injection timing determining arrangement stores an injection timing adjustment operation range in which the injection timing determining arrangement is configured to retard the timing of fuel injection by the first fuel injection valve as the temperature of cooling water falls, when injecting fuel during a compression stroke.

10. The engine control device according to claim 9 , wherein the injection timing adjustment operation range is a low-revolution, high-load operation range of the engine, and

wherein in the injection timing adjustment operation range, a threshold value of the engine load at which the timing of fuel injection by the first fuel injection valve is retarded is reduced as the temperature of cooling water falls.

11. The engine control device according to claim 2 , wherein the injection amount adjustment operation range is a low-revolution, high-load operation range of the engine.

12. The engine control device according to claim 11 , wherein in the injection amount adjustment operation range, a threshold value of the engine load at which the fuel injection ratio is increased is reduced as the temperature of cooling water falls.

13. The engine control device according to claim 2 , wherein the first fuel injection valve comprises a direct injection valve configured to directly inject fuel into a combustion chamber, and

wherein the second fuel injection valve comprises a port injection valve configured to inject fuel into an intake passage leading to the combustion chamber.

14. The engine control device according to claim 2 , wherein the first fuel injection valve comprises a lateral side direct injection valve mounted to one of an inner peripheral wall of a combustion chamber and a peripheral edge portion of a top of the combustion chamber on a side of a cylinder head, and configured to directly inject fuel into the combustion chamber, and

wherein the second fuel injection valve comprises an overhead direct injection valve mounted to a center of the top of the combustion chamber on the side of the cylinder head, and configured to directly inject fuel into the combustion chamber.

15. The engine control device according to claim 2 , further comprising an injection timing determining arrangement for determining timings of fuel injection by the first fuel injection valve and the second fuel injection valve;

wherein the injection timing determining arrangement stores an injection timing adjustment operation range in which the injection timing determining arrangement is configured to advance the timing of fuel injection by the first fuel injection valve as the temperature of cooling water falls, when injecting fuel during an intake stroke.

16. The engine control device according to claim 15 , wherein the injection timing adjustment operation range is a low-revolution, high-load operation range of the engine, and

wherein in the injection timing adjustment operation range, a threshold value of the engine load at which the timing of fuel injection by the first fuel injection valve is advanced is reduced as the temperature of cooling water falls.

17. The engine control device according to claim 2 , further comprising an injection timing determining arrangement for determining timings of fuel injection by the first fuel injection valve and the second fuel injection valve;

wherein the injection timing determining arrangement stores an injection timing adjustment operation range in which the injection timing determining arrangement is configured to retard the timing of fuel injection by the first fuel injection valve as the temperature of cooling water falls, when injecting fuel during a compression stroke.

18. The engine control device according to claim 17 , wherein the injection timing adjustment operation range is a low-revolution, high-load operation range of the engine, and

wherein in the injection timing adjustment operation range, a threshold value of the engine load at which the timing of fuel injection by the first fuel injection valve is retarded is reduced as the temperature of cooling water falls.