| 摘要 |
PURPOSE:To allow suitable predetermined air volume to always flow into a building even when a large atmospheric pressure difference occurs between the interior and the exterior of the building and to simultaneously prevent external noise from being introduced from a vent hole into a room. CONSTITUTION:The ventilating opening for a building comprises a constant air volume unit 2 and a silencing unit 3. The air volume unit has an outer cylinder 4 in which the front and rear sides are pivotally secured to a central shaft 10 and a predetermined number of ventilating holes 5 are provided axially of the peripheral side, an inner cylinder 12 in which ventilating holes 13 corresponding to the holes of the cylinder 4 are provided at the peripheral side, a pressure receiving plate 14 is provided at the rear side and which is so mounted at the central shaft as to slide in the cylinder 4, and a regulating spring 20 mounted on the central shaft between the rear end of the outer cylinder and the plate 14. The unit 3 has the inlet 22 of a cylindrical casing 21 engaged with the outer periphery of the front part of 1 the outer cylinder, a recess 26 formed at the inside between the inlet 22 of the casing and an outlet 23 and provided with a silencing material 27, and a ventilating passage 30 formed the cylinder 4 and the material 27 to allow the air from holes 5, 13 to flow out from the casing outlet 23. |
