| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent outdoor air of low temperature from flowing into a control box by a method wherein there is provided a sensor for sensing an outdoor temperature, a cooling fan is constituted of a fan which can be rotated in a normal direction and in opposite direction and then the fan is switched over to its normal rotation or its reverse rotation in response to the temperature of surrounding air detected by the sensor. SOLUTION: A cooling fan 40 which can be rotated in a normal direction or a reverse direction is arranged at an air discharging port 15 formed at an upper part of a control box 13. The cooling fan 40 is controlled by a fan control means 41. A detected temperature of a sensor 42 for use in detecting a temperature of the surrounding air is inputted to this fan control means 41, the inputted temperature is compared with data stored in the fan control means 41. If the outdoor temperature is higher than a set temperature, it is determined that the rotation is a normal rotation, and in turn if the detected temperature is lower than the set temperature, it is determined that the rotation is a reverse rotation and concurrently, the number of rotation of the normal direction and the number of rotation of the reverse rotation are determined in response to a deviation between the detected temperature and the set temperature. With such an arrangement as above, it is possible to prevent outdoor air of low temperature from feeding into the control box 13, resulting in preventing electronic component parts stored in the control box 13 from showing maloperation or failing to work properly.</p> |
