Abstract: The outlet duct extending outward from the air cleaner case is also extended inward into the air cleaner case with the same inner diameter such that the length of the part extending into the air cleaner is 10% to 25% of the axial length of the air cleaner element. By this, the distance from the opening of the outlet duct in the air cleaner case to the air flow sensor located in a downstream zone can be increased in an automobile engine, turbulence in the intake air flow can be considerably weakened at the air flow sensor, and air flow measurement not fluctuating widely can be obtained with an air flow measuring device having the same calibration program even when an air cleaner element of different type, i.e. of single type or double type, is used in an air cleaner case of the same design.

Abstract: The outlet duct extending outward from the air cleaner case is also extended inward into the air cleaner case with the same inner diameter such that the length of the part extending into the air cleaner is 10% to 25% of the axial length of the air cleaner element. By this, the distance from the opening of the outlet duct in the air cleaner case to the air flow sensor located in a downstream zone can be increased in an automobile engine, turbulence in the intake air flow can be considerably weakened at the air flow sensor, and air flow measurement not fluctuating widely can be obtained with an air flow measuring device having the same calibration program even when an air cleaner element of different type, i.e. of single type or double type, is used in an air cleaner case of the same design.