Self-cooling loop with electric ram fan for motor driven compressor

1. A motor driven compressor system for use in an on board inert gas generating system (OBIGGS), comprising:

a motor including an internal cooling loop, wherein the internal cooling loop draws cooling air from outside the motor driven compressor system;

at least one compressor driven by the motor; and

a heat exchanger in fluid communication with the at least one compressor and the cooling loop and arranged in a ram air duct; and

a fan arranged downstream from the heat exchanger in the ram air duct.

2. The motor driven compressor system of claim 1 , wherein the at least one compressor comprises a first compressor and a second compressor.

3. The motor driven compressor system of claim 1 , wherein the fan is an electric fan.

4. The motor driven compressor system of claim 1 , wherein the ram air duct feeds into an overboard exhaust downstream from the fan.

5. The motor driven compressor system of claim 1 , wherein the heat exchanger is an intercooler-type heat exchanger.

6. The motor driven compressor system of claim 1 , further comprising a bearing and rotor cooling loop separate from the internal cooling loop.

7. The motor driven compressor system of claim 6 , wherein the bearing and rotor cooling loop draws cooling air from an outlet of the heat exchanger.

8. The motor driven compressor system of claim 6 , wherein the bearing and rotor cooling loop feeds into the internal cooling loop.

9. The motor driven compressor system of claim 1 , further comprising an air separation module (ASM) configured to separate nitrogen-enriched air from oxygen-enriched air and in fluid communication with the heat exchanger.

10. An on board inert gas generating system (OBIGGS) for a gas turbine engine, comprising:

an air separation module (ASM) configured to separate nitrogen-enriched air from oxygen-enriched air;

a heat exchanger configured to cool air entering the ASM and arranged in a ram air duct; and

a motor driven compressor system feeding air into the ASM, and including a first compressor and a second compressor driven by a motor and an internal cooling loop, wherein the internal cooling loop draws cooling air from outside the OBIGGS, wherein air from the first compressor feeds into an overboard exhaust at a first mixing point and oxygen-enriched air feeds into the overboard exhaust at a second mixing point.

11. The OBIGGS of claim 10 , wherein a fan is arranged downstream from the heat exchanger and upstream from the overboard exhaust in the ram air duct.

12. The OBIGGS of claim 11 , wherein the second mixing points is downstream from the fan.

13. The OBIGGS of claim 11 , wherein the first and second mixing points are upstream from the fan.

14. The OBIGGS of claim 10 , wherein air exiting from the internal cooling loop is cooled by the heat exchanger.

15. The OBIGGS of claim 10 , further comprising a temperature regulator valve between the heat exchanger and the ASM.

16. A method of cooling an on board inert gas generating system (OBIGGS), comprising:

providing a motor driving at least one compressor;

providing a heat exchanger arranged in a ram air duct and configured to cool air passing to an air separation module (ASM) from the at least one compressor;

providing a fan arranged downstream from the heat exchanger in the ram air duct;

drawing cooling air from outside of the OBIGGS; and

providing the cooling air to a motor cooling loop.

17. The method of claim 16 , further comprising passing air exiting the cooling loop through the heat exchanger.

18. The method of claim 16 , further comprising drawing additional cooling air from an outlet of the heat exchanger and providing the additional cooling air to a bearing and rotor cooling loop.

19. The method of claim 18 , further comprising passing air exiting from the bearing and rotor cooling loop to the motor cooling loop.

20. The method of claim 16 , further comprising regulating a temperature of the air passing to the ASM from the at least one compressor.