Intake device for internal combustion engine

摘要

A hollow drum-like surge tank is supported for rotation in a casing. The surge tank communicates with the atmosphere by way of an opening formed in one end thereof and with the interior space of the casing by way of communicating holes formed in the peripheral surface of the surge tank. Intake pipes curl downwardly from intake ports of an engine and communicate with the internal space of the casing, whereby intake passages for the engine are formed through the surge tank, the interior space of the casing and the intake pipes. The surge tank is rotated back and forth about the longitudinal axis thereof, the amount of rotation depending on the engine speed, so that the distance between the communicating holes and the position in which the intake pipes communicate with the interior space of the casing is changed according to the engine speed, thereby changing the effective lengths of the intake passages for the engine according to the engine speed.