| 摘要 |
PURPOSE:To perform high efficiency, low heat generation, foreign noise-free, and quiet air flow rate regulation by setting the chopper frequency of a chopper system air flow rate controller outside the audible frequencies. CONSTITUTION:The basic oscillation frequencies of oscillation sections OP1 and OP2 are almost determined depending upon the time constants of a capacitor C1 and resistor R7. For example, the basic oscillation frequency can be set to approximately 30kHz and the value outside the audible frequencies. For instance, by setting the basic oscillation frequency to the time constants of R7 and C1 to less than 16Hz or the time constants R10 and C3 for the smoothing section to the value which is equal to 16Hz mentioned above, the chopping system air flow rate control is enabled below the audible frequencies. This makes the foreign noise from the blower motor 1 by the chopping cotrol outside the audible frequencies. As a result, the noise cannot actually be heard as a foreign one. |
