Air cycle machine with cooling air flow path
An air cycle machine comprises rotating components that include a fan, a compressor, and a first turbine. The air cycle machine also includes a cooling airflow path that receives cooling air from a cooling air source, directs the cooling air to an air-cooled bearing for at least one of the rotating components, and discharges the cooling air. The airflow path is isolated from an inlet of the compressor by a seal member, and the airflow path is configured to maintain pressure at the seal member above a pressure at the compressor inlet.
1. An air cycle machine, comprising:
rotating components including a fan, a compressor, and a first turbine; and
an airflow path that receives cooling air from a cooling air source, directs the cooling air to an air-cooled bearing for at least one of said rotating components, and discharges the cooling air;
wherein the airflow path is isolated from an inlet of the compressor by a seal member, and further wherein the airflow path terminates in a chamber that includes an outlet through an orifice that is configured to maintain pressure at the seal member above a pressure at the compressor inlet.
2. The air cycle machine of claim 1 , wherein the pressure at the compressor inlet is from 0 psig to 8.5 psig (0 kPa to 58.6 kPa).
3. The air cycle machine of claim 1 , wherein the pressure on the airflow path at the seal member is greater than the pressure at the at the compressor inlet by from 0 psi to 5 psi (0 kPa to 34.5 kPa).
4. The air cycle machine of claim 1 , wherein the outlet is in fluid communication with a ram airflow circuit.
5. The air cycle machine of claim 1 , wherein the airflow path is in fluid communication with a bearing on each of said fan, compressor, and turbine.
6. The air cycle machine of claim 1 , further comprising a second turbine having a bearing on the airflow path.
7. The air cycle machine of claim 1 wherein the seal is a labyrinth seal.
8. The air cycle machine of supply controller of claim 1 , wherein the airflow path is in fluid communication with a cooling air source selected from the turbine or the compressor.
9. The air cycle machine of claim 8 , wherein the cooling air source is the turbine when the aircraft is on the ground and is the compressor when the aircraft is at high altitude.
10. A method of cooling bearings on rotating components of an air cycle machine including a fan, a compressor, and a first turbine, comprising
introducing air from a cooling air source to a cooling airflow path;
flowing the cooling air along the airflow path to the bearings on at least one of the rotating components;
flowing the cooling air along the airflow path past a seal member that isolates the airflow path from an inlet of the compressor at a pressure above a pressure at the inlet of the compressor; and
discharging the cooling air from the airflow path through an orifice in a chamber, said orifice configured to maintain the pressure at the seal member above a pressure at the compressor inlet.
11. The method of claim 10 , wherein the pressure at the compressor inlet is from 0 psig to 8.5 psig (0 kPa to 58.6 kPa).
12. The method of claim 10 , wherein the pressure on the airflow path at the seal member is greater than the pressure at the at the compressor inlet by from 0 psi to 5 psi (0 kPa to 34.5 kPa).