Control device for internal combustion engine

A control device for an internal combustion engine that includes:

• a spark plug disposed at a combustion chamber top surface of a cylinder;
• a fuel injection valve configured to supply a fuel into the cylinder;
• three intake holes formed in the combustion chamber top surface, the area of a middle intake hole of the three intake holes being smaller than the sum of the areas of intake holes at opposite ends;
• at least one exhaust hole formed in the combustion chamber top surface;
• first intake valves configured to open and close the intake holes at the opposite ends;
• a second intake valve configured to open and close the middle intake hole;
• at least one exhaust valve configured to open and close the at least one exhaust hole;
• an intake variable valve device configured to separately control opening and closing of the first intake valves and opening and closing of the second intake valve;
• and
• an intake channel that includes first branch channels and a second branch channel, the first branch channels being connected to the intake holes at the opposite ends and being configured to produce a normal tumble flow that ascends on an intake side and descends on an exhaust side in the cylinder, and the second branch channel being connected to the middle intake hole and being configured such that a flow rate of intake air passing through a space on a side opposite to a center of a combustion chamber is greater than a flow rate of intake air passing through a space on a side of the middle intake hole closer to the center of the combustion chamber,
• wherein the control device is programmed, where increasing a flow coefficient of the first branch channels and the second branch channel is given a higher priority than enhancing a strength of the normal tumble flow, to control the intake variable valve device so as to select a first drive mode in which both the first intake valves and the second intake valve are opened and closed,
• wherein the control device is programmed, where the strength of the normal tumble flow is enhanced, to control the intake variable valve device so as to select a second drive mode in which the first intake valves are opened and closed while the second intake valve is neither opened nor closed, or the first intake valves are opened and closed while at least one of a lift amount and an operating angle of the second intake valve is set to be smaller than at least one of a lift amount and an operating angle of the second intake valve in the first drive mode, and
• wherein the control device is programmed, where production of the normal tumble flow is reduced, to control the intake variable valve device so as to select a third drive mode in which the second intake valve is opened and closed while the first intake valves are neither opened nor closed, or the second intake valve is opened and closed while at least one of a lift amount and an operating angle of the first intake valves is set to be smaller than at least one of a lift amount and an operating angle of the first intake valves in the first drive mode.