Patent Application
20140331692
This disclosure relates to a motor cooling system for a motor-driven compressor in an aircraft On Board Inert Gas Generating System (OBIGGS).
Aircraft and other vehicles may include an OBIGGS for generating inert gas. An OBIGGS generally includes an air separation module (ASM), which separates air into an inert nitrogen-enriched air (NEA) stream and a permeate oxygen enriched air (OEA) stream. The NEA stream may, for example, be used at the fuel tanks of an aircraft or vehicle.
OBIGGS designs may include a heat exchanger and a motor-driven compressor (MDC) system. The MDC system may include first and second compressors. The heat exchanger may be arranged in a ram-type air duct. During ground operation, cooling airflow over the heat exchanger is usually provided by an ejector downstream of the MDC system, which creates a low pressure area and draws air across the heat exchanger. The ejector air is generated from MDC second compressor outlet. During various flight and day temperatures (i.e., cold to hot day) conditions, the airflow over the heat exchanger may vary. For example, in the hot day condition there may not be enough airflow during ground operations to sufficiently cool the heat exchanger.
Additionally, the MDC is usually cooled by a cooling loop which may pass through an intercooler. Presently, the MDC cooling loop draws air from the outlet of the first compressor, and the air is ultimately discarded overboard after passing through the cooling loop. This lowers the efficiency of the MDC cooling loop during ground operations.
The ASM receives compressed air from the MDC. However, current MDC cooling designs do not effectively provide adequate ASM inlet temperature during cruising. Furthermore, the ejector can lower the flow rate of air available in the MDC system, which in turn decreases the amount of air available for the ASM.
A motor driven compressor system includes a motor with an internal cooling loop. The internal cooling loop draws cooling air from outside the motor driven compressor system. The compressor system also includes at least one compressor driven by the motor and a heat exchanger in fluid communication with the compressor and the cooling loop. The heat exchanger is arranged in a ram air duct. An on board inert gas generating system (OBIGGS) and a method including the motor driven compressor system are also disclosed.
The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
The MDC system 20 may include first and second compressors (C) 22 and 24, a motor 26, and a heat exchanger 28. The heat exchanger may be an intercooler-type heat exchanger. That is, cooling fluid and fluid traveling through the MDC system 20 do not mix. The heat exchanger 28 cools air for the ASM 12 and the motor 26. Cooling flow for the heat exchanger 28 is provided by a ram-type duct 30 in one example. Ram air flow may be controlled by a valve 32. Additional cooling air may also be provided by an auxiliary inlet 34 extending through the skin of an associated aircraft. An electric fan 36 is arranged downstream of the heat exchanger 28 in an overboard exhaust 38. A muffler 40 may be arranged downstream of the heat exchanger 28 as well.
The first and second compressors 22, 24 are driven by the motor 26. Air enters the MDC system 20 from an inlet 42. This air may be from a cabin or cargo compartment of an aircraft. A second muffler 44 and/or a valve 46 may be arranged downstream of the MDC inlet 42. Air is compressed by the first compressor 22 and sent to the heat exchanger 28. Air from the heat exchanger 28 goes to the second compressor 24. The flow passages for the system air within the heat exchanger 28 are not shown but would be apparent to a worker in the art. Air from the second compressor 24 cycles back to the heat exchanger 28 by the return line 48. Air from line 48 enters the heat exchanger 28 to become temperature conditioned air 18 that feeds into the filter 19. Air exiting from the motor 26 and permeate exiting from the ASM 12 via conduit 14 may feed into the overboard exhaust 38 at mixing points 39a and 39b, respectively. In the example shown in
The MDC system 20 includes a cooling loop 50. Hot compressed air from the first compressor 22 is pushed through an intercooler 100 via a conduit 51. The intercooler 100 feeds into the motor 26 for direct stator cooling. The hot compressed air is cooled by the heat exchanger 28 in the intercooler 100 and used to cool the motor 26. During flight, valve 60 is closed. The cooling ram air may then be used to cool the motor 26 via conduit 54. During ground operations, bearing and rotor cooling is provided by the stream 56 while check valve 61 is closed.
Referring to
The OBIGGS 10 may also include a temperature detection or regulation system. For example, in
Although example embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that and other reasons, the following claims should be studied to determine their true scope and content.
