| 摘要 |
A cooling device is provided with an inverter compressor (23). The set speed of the inverter compressor (23) can be changed in six stages from the first speed to the sixth speed, and the relationship between each set speed and the rotation speed is set so that higher the rotation speed, the greater the difference between the rotation speeds of adjacent stages. Thus, independent of the level of the rotation speed, the degree of an increase in cooling ability of each stage is substantially the same as those of the other stages. When control of the inverter compressor (23) is performed so as to increase or decrease its speed on a stage by stage basis depending on whether the actual degree of temperature fall is greater than a target degree of temperature fall, the amounts of changes in cooling ability can be maintained at almost the same level, and no excess or deficiency of cooling ability occurs. That is, an up-and-down of cooling speed can be limited to a minimum level and control for reducing the temperature in a chamber can be stably performed following predetermined cooling characteristics. |
