Air cleaner of internal combustion engine

1. An air cleaner of an internal combustion engine, wherein the air cleaner is provided with a first housing including an inlet, a second housing including an outlet, and a filter element located between the first housing and the second housing, the air cleaner comprising:

a Helmholtz resonator arranged inside the first housing;

an upright wall that projects from a bottom wall of the first housing toward the filter element and extends in an axial direction of the inlet, wherein the upright wall forms a chamber of the Helmholtz resonator;

a noise-absorption region defined by the upright wall, a side wall of the first housing, the bottom wall, and the filter element, wherein the noise-absorption region leads to the inlet and extends in the axial direction;

a lid that closes an opening defined by the upright wall and defines part of the chamber; and

a communication pipe that connects an inner side and an outer side of the chamber and forms the Helmholtz resonator with the chamber, wherein the communication pipe is integrated with the lid along a surface of the lid and includes an exit projecting into the chamber toward the bottom wall of the first housing.

2. The air cleaner according to claim 1 , wherein the upright wall extends beyond one half of a length of the first housing in the axial direction.

3. The air cleaner according to claim 1 , wherein

the lid includes a first plate and a second plate,

the first plate includes a plate portion and a semi-cylindrical bulged portion bulged from the plate portion toward the inner side of the chamber, and

the second plate is coupled to the plate portion and forms the communication pipe with the bulged portion.

4. The air cleaner according to claim 3 , wherein the exit is a cylindrical exit projecting into the chamber from the bulged portion.

5. The air cleaner according to claim 1 , wherein the communication pipe includes an entrance that projects into the noise-absorption region.