Scroll-type fluid machine with counter-weight

摘要

A scroll-type fluid machine includes a fixed scroll having a spiral wall; an orbiting scroll having a base plate which is on one side provided with a spiral wall, the orbiting scroll having the spiral wall combined with the spiral wall of the fixed scroll. A rotation preventing mechanism prevents the orbiting scroll from rotating about its own axis. A driving shaft is driven by a driving source, which has an eccentric portion, the eccentric portion causing the orbiting scroll to carry out orbiting movement through an orbiting bearing. A counter-weight is coupled to the driving shaft in such manner that it takes an eccentric position at the side remote from the eccentric portion of the driving shaft and it has a play with respect to the driving shaft in a radial direction, which can balance with at least part of a centrifugal force caused at the orbiting scroll side, and which has radial movement controlled by the orbiting scroll side.