NOVELTY - The fluid machine (14) includes a drive shaft (72) integrally and coaxially connecting the inner tooth (66) of a pump unit (16), the axial portion (56) of an expander unit (20), and the rotor (96) of an electric power generation unit (26). The one-way clutch (95) between the drive shaft and the axial portion interrupts power transmission between both or permits power transmission to the drive shaft from the axial portion when the rotation speed of the axial portion is lower or higher than the shaft rotation speed. A power transmission unit (30) provides motive power to the shaft from outside.    USE - Fluid machine for Rankine circuit (claimed) for waste heat utilization system for vehicle (claimed).    ADVANTAGE - The pump unit, expansion unit and electric power generation unit are coaxial with each other, achieving size reduction of the machine. The pump unit can be started with motive power from outside, avoiding need for the electric power generation unit to function as an electric motor while allowing the same unit to achieve high electric power generation efficiency. The electric power generation unit does not require a brush, making the same unit lightweight and easier to maintain. Since rotary bodies of all units are integrally connected to one drive shaft, all units can be operated at the same time. The capacity of the expansion unit can be adjusted so as to reduce drive shaft load and consumption motive power of the machine as a whole. Waste heat of the engine is converted into electricity, improving fuel consumption. The engine is connected with the power transmission unit to convert kinetic energy into electricity at time of vehicle braking or deceleration, further improving fuel consumption.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a Rankine circuit; and    (2) a waste heat utilization system for a vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows the longitudinal cross-sectional view of a fluid machine. (Drawing includes non-English language text)    Fluid machine (14)    Pump unit (16)    Expander unit (20)    Electric power generation unit (26)    Power transmission unit (30)    Axial portion (56)    Inner tooth (66)    Drive shaft (72)    One-way clutch (95)    Rotor (96)