To improve fuel consumption by arranging a structurally simple and durable ion generator in an air cleaner box.

The fuel consumption is improved by being arranged in the air cleaner box 4 by improving ventilation performance by being hardened in a simple mesh shape by mixing tourmaline and silicone rubber by a proper quantity. Natural stone tourmaline is processed into powder, and the silicone rubber and tourmaline powder are mixed by a proper quantity, and hardened in a mesh shape by inserting a metallic wire inside. The eco-net is arranged on the air filter outside air side in the air cleaner box.