US Patent 12110900 Air cycle machine bypass duct

An environmental control system includes a rotary machine, a first bypass duct, and a first check valve in the first bypass duct. The rotary machine includes a compressor section and a first turbine section. Each section of the rotary machine includes an inlet, an outlet, a duct extending between the inlet and the outlet, and an impeller in the duct. The rotary machine also includes a tie rod mechanically connecting the compressor impeller and the first turbine impeller. The first bypass duct is between the compressor section and the first turbine inlet. The check valve opens the first bypass duct when an air pressure in the compressor inlet is higher than an air pressure in the first turbine inlet.