Intake control device for internal combustion engine

An internal combustion engine intake control device comprising:

• a surge tank;
• a first intake passage that extends from the surge tank and is connected to a combustion chamber;
• a second intake passage that extends from the surge tank and merges with the first intake passage between the surge tank and the combustion chamber;
• an intake passage length-changing valve, provided within the first intake passage and upstream of a connection point where the second intake passage connects to the first intake passage, that opens and closes the first intake passage;
• a partition, disposed in the first intake passage, that partitions an internal space in the first intake passage downstream of the connection point along an axis of the first intake passage to form two partitioned intake passages;
• and
• a tumble control valve that:
• opens and closes one of the partitioned intake passages, wherein when the tumble control valve closes one of the partitioned intake passages air drawn into the combustion chamber through the open partitioned intake passage forms a tumble flow,
• is attached to the partition,
• is rotatable about a pivot shaft that is attached to the partition, the pivot shaft being attached to the partition proximate to a downstream end of the partition that is near the combustion chamber, and
• has a plate-shaped valve element that:
• is rotatable about the pivot shaft,
• is parallel to the partition when the tumble control valve has opened the one of the partitioned intake passages, and
• is in or near the same plane as the partition when the tunable control valve has opened the partitioned intake passage, wherein:
• the length of the second intake passage from the surge tank to the first intake passage is longer than the length of the first intake passage from the surge tank to the connection point and the cross-sectional area of the second intake passage is smaller than the cross-sectional area of the first intake passage from the surge tank to the connection point,
• the second intake passage is connected to the first intake passage from a direction generally perpendicular to the partition, and
• the tumble control valve opens and closes the partitioned intake passage formed on the side opposite the side on which the second intake passage is connected to the first intake passage with respect to the partition.