JPS5685595A - Blower - Google Patents

Abstract

PURPOSE: To decrease resonance frequency, thereby to lower the noise level of the blower, by a method wherein the change is given to the sectional form of the exhaust to fit in with the velocity distribution of the air flow, by the air flow formed by the impeller.

CONSTITUTION: The inside of the wall 1 of the exhaust is covered with the flexible and elastic diaphragm 2, an airtight chamber 3 is made between the wall 1 and the diaphragm 2, the intercoupling hole 4 going through the wall 1 of the exhaust and being open to the airtight chamber 3 is provided, and the hole 4 is connected with the pressure source outside. With this constitution, the wind-velocity distribution is produced at the mouth of exhaust during the fan rotating. In the part where the velocity is fast, the air will go out from the exhaust by pushing the diaphragm 2 away, but in the part where the velocity is slow, the diaphragm 2 is moved to the direction throttled toward the inside of the exhaust because the expansive force of the airtight chamber 3 surpassed the moving pressure of thw wind-velocity, the exhaust section is decided in the position where the exhausted air pressure and the expansive force of the airtight chamber 3 balances, and the exhaust is throttled to the form to fit in with the velocity distribution at the mouth of the exhaust. Thereby, the resonance frequency produced within the casing is decreased and the noise level can be lowered.

COPYRIGHT: (C)1981,JPO&Japio