Intake device of an internal combustion engine

Claim 1

A multi-cylinder internal combustion engine having a cylinder head and a plurality of cylinders, each cylinder having a combustion chamber, a first intake valve arranged in the combustion chamber, a first intake passage having an inlet and an outlet which is connected to the combustion chamber via the first intake valve, a second intake valve arranged in the combustion chamber, a second intake passage having an inlet and an outlet which is connected to the combustion chamber via the second intake valve, a common intake passage connected to the inlets of the first intake passage and the second intake passage, a first throttle valve arranged in the common intake passage, and a normally closed second throttle valve arranged in the second intake passage and opened when the engine load or the engine speed is increased beyond a predetermined level, wherein the improvement comprises a blind common connecting passage, a plurality of branch passages extending from the blind common connecting passage, each branch passage being open to said second intake passage of a corresponding cylinder at a location downstream of said second throttle valve of the corresponding cylinder, each of said branch passages having an opening arranged in the vicinity of a valve head of a corresponding second intake valve, directed to a gap formed between said valve head and a valve seat of said corresponding second intake valve, and directed tangentially to a circumferential wall of the corresponding combustion chamber, the second throttle valve of each cylidner being closed when a selectable one of the speed and load of the engine is below a predetermined level.