Control device of internal-combustion engine

1. A control device of an internal-combustion engine configured to control an internal-combustion engine including a variable valve timing mechanism that adjustably changes a valve-opening timing of an intake valve comprising:

a controller that:

sets a target valve-opening timing of the intake valve of the variable valve timing mechanism; and

operates the variable valve timing mechanism on the basis of the target valve-opening timing set in the setting step,

wherein the setting step sets a first target valve-opening timing to be set when a load of the internal-combustion engine is within a first range between a lower end and a higher end of the load that causes an abnormal combustion which is later than both a second target valve-opening timing to be set when the load is within a second range in which the load is lower than the lower end, and a third target valve-opening timing to be set when the load is within a third range in which the load is higher than the higher end.

2. The control device of an internal-combustion engine according to claim 1 , wherein

the controller sets the second target valve-opening timing later with an increase in the load of the internal-combustion engine.

3. The control device of an internal-combustion engine according to claim 1 , wherein

the controller sets the third target valve-opening timing earlier with an increase in the load of the internal-combustion engine.

4. The control device of an internal-combustion engine according to claim 1 , wherein

the internal-combustion engine includes a supercharger, and

the third range includes a range of a load in which the engine is supercharged by the supercharger.

5. The control device of an internal-combustion engine according to claim 4 , wherein

when the load is a maximum load in the third range, the controller sets the target valve-opening timing to the latest timing among valve-opening timings at which supercharging to be carried out by the supercharger is realizable.

6. The control device of an internal-combustion engine according to claim 1 , wherein

the internal-combustion engine further includes an exhaust valve, and

in the second range, the controller sets the valve-opening timing of the intake valve in such a manner as to provide a valve overlap period in which the exhaust valve and the intake valve are simultaneously in an opened state.

7. The control device of an internal-combustion engine according to claim 1 , wherein

the first range is a range of the load in which an abnormal combustion occurs, and is set variable according to a rotational speed of the internal-combustion engine.

8. The control device of an internal-combustion engine according to claim 1 , wherein

the controller holds the first target valve-opening timing at a constant valve-opening timing.

9. The control device of an internal-combustion engine according to claim 1 , wherein

the controller sets a fourth target valve-opening timing to be set when the internal-combustion engine is in an idle state and the load is within a fourth range that is lower than the load in the second range, the fourth target valve opening being set later than the first target valve-opening timing.

10. A control device of an internal-combustion engine configured to control an internal-combustion engine including a variable valve timing mechanism that adjustably changes a valve-opening timing of an intake valve comprising:

a controller that:

sets a target valve-opening timing of the intake valve of the variable valve timing mechanism; and

operates the variable valve timing mechanism on the basis of the target valve-opening timing set in the setting step,

wherein the setting step sets a first target valve-opening timing to be set when a load of the internal-combustion engine is within a first range which is a predetermined range later than both a second target valve-opening timing to be set when the load is within a second range in which the load is lower than the first range, and a third target valve-opening timing to be set when the load is within a third range in which the load is higher than the first range, and

the controller:

sets the second target valve-opening timing later with an increase in the load of the internal-combustion engine,

sets the third target valve-opening timing earlier with an increase in the load of the internal-combustion engine, and

holds the first target valve-opening timing at a constant valve-opening timing.

11. A control device of an internal-combustion engine configured to control an internal-combustion engine including a variable valve timing mechanism that adjustably changes a valve-opening timing of an intake valve comprising:

a controller that:

sets a target valve-opening timing of the intake valve of the variable valve timing mechanism; and

operates the variable valve timing mechanism on the basis of the target valve-opening timing set in the setting step,

wherein the setting step sets a first target valve-opening timing to be set when a load of the internal-combustion engine is within a first range between a lower end and a higher end of the load that causes an abnormal combustion which is later than both a second target valve-opening timing to be set when the load is within a second range in which the load is lower than the lower end, and a third target valve-opening timing to be set when the load is within a third range in which the load is higher than the higher end, and

the controller:

sets the second target valve-opening timing later with an increase in the load of the internal-combustion engine,

sets the third target valve-opening timing earlier with an increase in the load of the internal-combustion engine,

holds the first target valve-opening timing at a constant valve-opening timing, and

sets a fourth target valve-opening timing to be set when the internal-combustion engine is in an idle state and the load is within a fourth range that is lower than the load in the second range, the fourth target valve opening being set later than the first target valve-opening timing.