A fluid machinery includes a
helical mechanism connected to a driving mechanism, which is driven via a
crank shaft. The
helical mechanism includes a cylinder defining an inner space, a roller disposed inside the cylinder so as to be rotated in an eccentric manner, the roller being formed with a plurality of
helical grooves on an outer
peripheral surface, and at least one seal ring groove between respective helical grooves, a plurality of helical blades fitted to the helical grooves so as to be disposed between as inner
peripheral surface of the cylinder and the outer
peripheral surface of the roller, and at least one seal ring fitted to the seal ring groove so as to tightly seal the inner space as a plurality of operation sections. Furthermore, a plurality of suction ports and a plurality of drain ports, associated with respective operation sections, communicate with each other.