US Patent 7121817 Scroll fluid machine comprising compressing and expanding sections

A scroll fluid machine comprises an orbiting scroll and front and rear stationary scrolls. The orbiting scroll is driven by a driving shaft via an eccentric portion and has front and rear orbiting scroll wraps. The front and rear stationary scroll have front and rear orbiting scroll wraps respectively. The orbiting scroll is revolved by the driving shaft with respect to the stationary scrolls while the front and rear orbiting scroll wraps are engaged with the front and rear stationary scroll wraps to create front compressing and rear expanding sections. Fluid expanded and cooled in the expanding section is used for cooling parts of the machine.