| 摘要 |
PROBLEM TO BE SOLVED: To provide a stable cooling construction without changing a cooling air amount circulating in an instrument and an air pressure distribution of cooling air even when power supply voltage or frequency is changed. SOLUTION: A flower guide 67 including an air suction port 65 and an exhaust port 66 therein is disposed around a circulation fan motor 62, and a damper 70 is constructed at the air suction port 65 or air exhaust port 66 of the flower guide 67, which serves to change an opening area of the air suction port 65 or the exhaust port 66 owing to air pressure generated in response to the number of revolutions of the circulation fan motor 62. Accordingly, a stable cooling construction is ensured without changing a cooling air amount circulation in the instrument and an air pressure distribution of cooling air even when power supply voltage or frequency is changed.
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