Refrigerating storage cabinet

A refrigerating storage cabinet comprising:

• a refrigeration unit for refrigerating an inner atmosphere, the refrigeration unit having a speed-controllable inverter compressor and an evaporator, the compressor having a plurality of performance levels;
• a temperature sensor configured to detect a current temperature of the inner atmosphere at predetermined intervals of operating time;
• and
• an operation control unit configured to control the inverter compressor by selecting one of the plurality of performance levels based on the current temperature, the operation control unit including:
• a temperature change computing section configured to compute a current temperature reduction degree at the predetermined intervals of operating time, based on the current temperature and a previously detected temperature;
• a target temperature reduction degree output section configured to obtain a target temperature reduction degree associated with the current temperature;
• a comparing section configured to compare the current temperature reduction degree to the target reduction degree;
• and
• a compressor control section configured to select one of the plurality of performance levels based on a result of the comparison made by the comparing section,
• the operation control unit being configured to control the inverter compressor so that a rotational speed of the inverter compressor is increased when the comparing section indicates that the current temperature reduction degree is smaller than the target temperature reduction degree and the rotational speed of the inverter compressor is decreased when the comparing section indicates that the current temperature reduction degree is larger than the target temperature reduction degree,
• the refrigerating storage cabinet further comprising a storing unit configured to store a reference table having a plurality of target temperature reduction degrees associated with a plurality of temperatures individually representing a temperature of the inner atmosphere, wherein
• the plurality of target temperature reduction degrees is predetermined according to an ideal cooling characteristic that indicates a target temperature as a function of operating time, the target temperature decreasing gradually with a lapse of operating time according to the ideal cooling characteristic;
• and
• the target temperature reduction degree output section obtains the target temperature reduction degree by retrieving a target temperature reduction degree associated with the current from the reference table, and
• the ideal cooling characteristic includes a pull down characteristic for a temperature range from above a predetermined high temperature to near a set temperature;
• and
• the predetermined high temperature is set to be higher than the set temperature by a value larger than a predetermined value;
• and
• the pull down characteristic includes a first pull down zone and a second pull down zone;
• the pull down characteristic includes a pull down characteristic that is provided for the first pull down zone and is a linear function;
• and
• the pull down characteristic includes a pull down characteristic that is provided for the second pull down zone and is a quadratic function.