Compressor and method of using compressor

A compressor comprising:

• a plurality of housing members forming a body;
• a fastener that couples said plurality of housing members to one another;
• an electromagnetic clutch provided on one end side of said body;
• a drive shaft inserted through said body and coupled to a power source via said electromagnetic clutch;
• said body having an outer lateral face side that extends parallel to said drive shaft;
• a movable member that moves in association with said drive shaft to compress a fluid;
• a detection body that moves in association with said drive shaft;
• and
• a magnetic sensor to detect a rotational state of said drive shaft by means of said detection body, said magnetic sensor having a magnetic impedance element that detects changes in a circulative magnetic flux, the circulative magnetic flux including only the magnetic flux leaking out from said electromagnetic clutch that is sequentially conducted from an outer lateral face side of said body to said detection body, via said fastener, and said drive shaft so as to form a circulative magnetic path,
• wherein
• said detection body and said drive shaft are made of a ferromagnetic material,
• said magnetic sensor is provided at or near the outer lateral face side of said body,
• said detection body has a radially extending end face which faces the outer lateral face side of the body and said magnetic sensor via said fastener,
• said magnetic sensor is located radially outwardly from the radially extending end face of the detection body,
• said magnetic sensor is in proximity to said fastener, and
• a length of the space between the fastener and the outer lateral face side of the body directly above said magnetic sensor in a direction perpendicular to said drive shaft is less than the length of the outer lateral face side of the body directly above said magnetic sensor in a direction perpendicular to said drive shaft.