Environmental noise pollution reduction device of running road vehicle

In a road vehicle body including an engine compartment in which an engine is disposed, the engine compartment being defined by two opposite longitudinal side panels, a hood spanning between the top portions of the side panels, a fire-wall separating a passenger compartment from the engine compartment, and a front wall oppositely disposed to the fire-wall and having therethrough openings for inducting cooling air, the engine compartment having at its bottom portion a generally rectangular opening in plan, the improvement comprising:

• first and second under-covers which are of generally elongate rectangular shape in plan and generally of the same size for partly covering the rectangular opening to reflect the engine noise, said first and second under-covers being oppositely disposed longitudinally along the bottom portions of the side panels and extending from the front wall to the fire-wall, the opposed edges of said first and second under-covers being separated from each other by a rectangular ventilation opening therebetween, the bottom portion of the engine being substantially spaced apart from the plane of the rectangular ventilation opening and substantially closer to the hood than the plane of the rectangular ventilation opening, said first and second under-covers being respectively secured to two opposite rigid side members which extend from the front wall toward the fire-wall and are attached to the bottom portions of the side panels, the engine being mounted on the side members, the width of said rectangular ventilation opening defined between the opposed edges of the under-covers being in the range of 60 to 75% of the width of said rectangular opening defined between the opposed inner sides of the side members;
• and
• sound absorbent material attached to the inner surface of the hood for absorbing the noise reflected by the under-covers into the engine compartment.