Scroll compressor

A scroll compressor operable at variable speeds, comprising:

• a fixed scroll wherein a spiral shaped base wrap rises from a base plate, and
• an orbiting scroll wherein a base wrap having generally the same spiral shape rises from a base plate,
• said fixed scroll and orbiting scroll being meshed together so as to form a plurality of compression chambers therebetween, and said orbiting scroll being made to orbitally move at variable speed in relation to said fixed scroll without itself rotating;
• wherein
• intake and containment capacity of one of a pair of compression chambers formed by said base wraps is made smaller than that of other;
• an extension wrap is provided, in the base wrap forming the compression chamber having smaller volume, extending from a position at spiral end thereof, along spiral shape thereof;
• and
• a displacement surface displaced in direction in which wrap thickness becomes thinner is made on at least one of an inner wall of said extension wrap and outer wall of other wrap in opposition thereto, in an amount such that a predetermined containment capacity is obtained by the extension wrap in high speed operation, while said containment capacity is not obtained by the extension wrap in low speed operation.