Rankine cycle apparatus

A complex fluid machine incorporated in a Rankine cycle apparatus, the Rankine cycle apparatus having a circuit including a pump for pumping a working fluid, a heat exchanger for causing heat exchange between the working fluid received from the pump and fluid supplied from an exhaust heat source, and an expanding portion that expands the working fluid that has been exposed to the heat exchange in the heat exchanger, thereby producing mechanical energy through the expansion, the complex fluid machine comprising a housing for accommodating the expanding portion and the pump, wherein

• the expanding portion includes a fixed scroll, a movable scroll that orbits with respect to the fixed scroll as a drive shaft rotates, and a back pressure chamber arranged at the side corresponding to a backside of the movable scroll opposite to the surface facing the fixed scroll, and
• the complex fluid machine further includes an inlet mechanism for introducing the working fluid from a high pressure zone, which extends from an outlet side of the pump to an inlet of the heat exchanger, to the back pressure chamber, thereby producing back pressure that presses the movable scroll against the fixed scroll along the axial direction of the drive shaft.