Compressor capacity control method and device for controlling the capacity of a compressor

A device for controlling the capacity of a compressor comprising:

• a pressure sensor that detects a pressure of air discharged from a compressor;
• an unloading mechanism that changes the operation of the compressor between a loading state and an unloading state;
• and
• a control mechanism including a timer that controls the operation of the unloading mechanism;
• wherein the control mechanism controls the unloading mechanism to change the operation of the compressor from the unloading state to the loading state when the pressure detected by the pressure sensor is less than a lower limit pressure;
• wherein the control mechanism controls the operation of the unloading mechanism to change the operation of the compressor from a loading state to an unloading state when the pressure detected by the pressure sensor exceeds an upper limit pressure;
• wherein the control mechanism controls the operation of the unloading mechanism to change the operation of the compressor from a loading state to an unloading state when the pressure detected by the pressure sensor is less than the upper limit pressure but greater than a minimum level pressure and an elapsed time measured by the timer is greater than a predetermined time duration;
• and
• wherein the minimum level pressure is between the lower limit pressure and the upper limit pressure.

A method for controlling the capacity of a compressor comprising:

• detecting a pressure of air discharged from a compressor with a pressure sensor;
• unloading mechanism that changing the operation of the compressor between a loading state and an unloading state with an unloading mechanism;
• controlling the unloading mechanism with a control mechanism to change the operation of the compressor from the unloading state to the loading state when the pressure detected by the pressure sensor is less than a lower limit pressure;
• controlling the operation of the unloading mechanism with the control mechanism to change the operation of the compressor from a loading state to an unloading state when the pressure detected by the pressure sensor exceeds an upper limit pressure;
• and
• controlling the operation of the unloading mechanism with the control mechanism to change the operation of the compressor from a loading state to an unloading state when the pressure detected by the pressure sensor is less than the upper limit pressure but greater than a minimum level pressure and an elapsed time measured by the timer is greater than a predetermined time duration, wherein the minimum level pressure is between the lower limit pressure and the upper limit pressure.