US Patent 7201568 Scroll fluid machine

A scroll fluid machine has a low-pressure stage compression part for compressing a fluid sucked in from the outside between mutually overlapping wrap portions of two scroll members performing a relative orbiting motion and a high-pressure stage compression part for compressing the fluid sucked in from the low-pressure stage compression part between mutually overlapping wrap portions of two scroll members performing a relative orbiting motion. The scroll members in the low-pressure stage compression part have a larger radial gap between the wrap portions than that of the scroll members in the high-pressure stage compression part.