| 摘要 |
PURPOSE: To suppress an interference sound and a burble sound to the utmost while suppressing an increase in an airflow resistance and thereby to lower a noise level of an outdoor machine by specifying a gap between supports of a grille and by shaping a section in the horizontal direction practically like an ellipse of which the ratio between the short and long axes and the length of the short axis are specified. CONSTITUTION: A dimension (c) of a gap between horizontal supports 9 each having a section shaped practically like an ellipse having a short axis (a) and a long axis (b) is made about 9mm which is the maximum dimension for preventing insertion of a finger in a testing method described in JIS C9612. In a grille prepared in this way, front-edge burble is hardly caused even when a flow from the front varies, and turbulence of the rear flow is also reduced. Besides, the mutual operation of the horizontal supports 9 produces an effect of suppressing the burble. By shaping the horizontal section practically like an ellipse of which the ratio a/b between the short and long axes is 0.3-0.45 and the length of the short axis 4-9mm, besides, the grille wherein the burble is reduced with an increase in an airflow resistance suppressed and whereby a noise level of an outdoor machine is lowered is obtained. |
