Dual capacity compressor

A dual capacity compressor comprising:

• a power generating part including a reversible motor and a crank shaft inserted in the motor;
• a compression part including a cylinder, a piston in the cylinder, and a connecting rod connected to the piston;
• a crank pin in an upper part of the crank shaft eccentric to an axis of the crank shaft;
• an eccentric sleeve having an inside circumferential surface rotatably fitted to an outside circumferential surface of the crank pin, and an outside circumferential surface rotatably fitted to an end of the connecting rod;
• a key member for coupling the eccentric sleeve with the crank pin positively in all rotation directions of the motor;
• and
• damping means for damping impact occurred between the eccentric sleeve and members adjoin thereto;
• thereby providing different compression capacities by re-arranging the eccentric sleeve that changes an effective eccentricity and a piston displacement following change of a direction of rotation of the motor, and preventing relative motion between the crank pin and the eccentric sleeve during operation by means of the key member actually regardless of the direction of rotation of the motor.