Scroll compressor having a pressure relief mechanism using an oldham coupling

A scroll compressor comprises a fixed scroll defined by wrap teeth having a spiral shape which is formed on one side of a first bed plate, an orbital scroll defined by wrap teeth having substantially the same spiral shape as that of the fixed scroll which is formed on one side of a second bed plate, said both wrap teeth are arranged so that they have a relative phase difference differentiated by 180 degrees and form a plurality of closed compression chambers, a volume of said closed compression chambers are gradually decreased and compressed by a relative orbital motion of the orbital scroll and the fixed scroll, the scroll compressor comprising:

• rotation constraining means for restricting a rotation of the orbital scroll toward a principal axis rotational direction and maintaining the relative phase difference of said both wrap teeth differentiated by substantially 180 degrees, and for extending a constraining range of the orbital scroll toward the principal axis reverse rotational direction and changing the relative phase difference of said both wrap teeth;
• and
• compression chamber torque forming means for causing a pressure in first compression chambers which is larger than that in second compression chambers when the pressure in the compression chambers rises up abnormally high, wherein the first compression chambers are formed between a wrap member inside surface of the fixed scroll and a wrap member outside surface of the orbital scroll and the second compression chambers are formed between a wrap member outside surface of the fixed scroll and a wrap member inside surface of the orbital scroll, wherein a rotation of the orbital scroll about its own axis toward a reverse rotational direction of the principal axis permits a clearance to be formed between contact points of the fixed scroll and the orbital scroll in a vicinity of the first compression chambers and causes a zero clearance between the contact points of the fixed scroll and the orbital scroll in a vicinity of the second compression chambers.