Ventilator

Abstract

A main body casing of a ventilator is formed with an outer airflow opening and an inner airflow opening and a ventilating path for connecting these airflow openings is formed in the main body casing. The ventilator ventilates a room and prevents entry of noise from outside into the room through the ventilating path. The ventilating path is bifurcated and these two ventilating paths have different lengths from each other so that a noise sound wave entering through one of the ventilating paths and a noise sound wave entering through the other ventilating path are out of phase with each other to cancel out each other's sound wave energy when the sound waves meet.

1 . A ventilator which comprises a main body casing having an outer wall and an inner wall, in which a ventilating path for connecting an airflow opening formed in the outer wall and an airflow opening formed in the inner wall is provided in the main body casing, and the ventilator ventilates a room on which the ventilator is attached through the inner wall thereof and prevents entry of noise from outside into the room through the ventilating path,
 wherein the ventilating path is bifurcated into two, and the bifurcated two ventilating paths each extending to a confluence of the ventilating paths have different lengths from each other so that a noise sound wave passing through one of the ventilating paths and a noise sound wave passing through the other ventilating path are out of phase with each other to cancel out each other's energy when the sound waves meet at the confluence.   
   
   
       2 . The ventilator according to  claim 1 , wherein a box-shaped sound-deadening chamber stuffed with sound-deadening material is disposed at a central portion in the main body casing to receive the sound wave reflected by outer faces of partition walls forming the ventilating paths. 
   
   
       3 . The ventilator according to  claim 1 , wherein a part of the one ventilating path and a part of the other ventilating path are respectively formed of punched panels, and sound-deadening chambers stuffed with sound-deadening material are formed outside the punched panels and between the punched panels and the wall forming the main body casing. 
   
   
       4 . The ventilator according to  claim 1 , wherein a sound wave reflecting plate is provided in a position in the main body casing which faces the airflow opening formed in the outer side wall to reflect the sound waves entering the main body casing through the airflow opening toward the airflow opening, thereby introducing the sound waves which have not been discharged outside the main body casing through the airflow opening into the bifurcated two ventilating paths.