Integrated air conditioning and power unit

An integrated air conditioning and power unit is provided for use with an aircraft. The system includes an air turbine 42 having air passages connected to an engine 10 of the aircraft for receiving bleed air and/or ram air for driving the air turbine 42. A motor/generator 104 is drivingly connected to the air turbine 42. The motor/generator 104 is capable of drawing electricity from an aircraft primary power system for driving the motor or generating electricity which is delivered to the primary power system 108. An air compressor 54 is drivingly connected to the motor/generator 104 and is provided with an air passage which receives bleed air 32 and/or ram air 30 from the aircraft engine 10. A cooling system 71 is provided including a system compressor 81 drivingly connected to the motor/generator 104. A cooling system evaporator 70 and a condenser 92 are connected to the system compressor by fluid passages. The air compressor 54 includes an air outlet for providing pressurized air which is cooled by the cooling system.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates to secondary power systems for aircraft and, 
in particular, to an integrated air conditioning and power unit for an 
aircraft. 
2. Background Art 
In modern high-speed aircraft, weight reduction, space reduction, and cost 
reduction are highly important. Currently, gas turbine auxiliary power 
units (APU) are being used to start the thrust engines, and to power the 
air conditioning and environmental control systems while the aircraft is 
on the ground. U.S. Pat. No. 4,684,081 issued to Cronin discloses a system 
which integrates the auxiliary power unit (APU), emergency power unit 
(EPU), environmental control system (ECS), and engine start system (ESS) 
in order to reduce the number of parts, weight, and size of the aircraft. 
The auxiliary power unit is commonly considered to be a low-utilization 
device that adds weight and complexity to the airplane while providing 
little operational benefit during most flight conditions. However, the 
elimination of the APU would require that a substantial pneumatic ground 
cart and electric ground power cart accompany the aircraft until the main 
thrust engines are started. 
3. Disclosure of Invention 
The system of the present invention provides an integrated air 
conditioning/emergency power system (IAC/EPS) which utilizes electric 
motor driven vapor cycle refrigeration machinery in combination with an 
air turbine and compressor to produce an air conditioning/environmental 
control module which will also serve as a source for emergency electrical 
power. 
The system provides an integrated air conditioning and power unit for use 
with an aircraft including an air turbine having air passages connected to 
one of an air inlet and a compressor of a gas turbine engine of the 
aircraft. A motor/generator is provided drivingly attached to the air 
turbine and connected to an electric power converter which is connected to 
a primary power system. The motor/generator is capable of drawing 
electricity from the primary power system and of generating electricity 
which is delivered to the primary power system. An air compressor is 
drivingly connected to the motor/generator. The air compressor includes an 
air passage connected to one of the air inlet and the compressor of the 
engine. A cooling system is provided which includes a system compressor 
drivingly connected to the motor/generator. A first evaporator is 
connected to the system compressor by a fluid passage, and a condenser is 
connected between the system compressor and the first evaporator by fluid 
passages. The air compressor includes an air outlet for providing 
pressurized air which is cooled by the first evaporator of the cooling 
system. 
The cooling system further includes a second evaporator fluidly connected 
to the system compressor and a recirculation fan for drawing air from 
inside the aircraft cabin through the second evaporator. 
The integrated air conditioning/emergency power system according to the 
present invention provides mechanical and electrical equipment in such way 
that the same equipment or major parts of it can be used to perform a 
multiplicity of functions. In this manner, a minimum of equipment is 
installed on the aircraft to perform all the required functions and to 
provide the required redundancy and reliability. 
The integrated air conditioning/emergency power system according to the 
present invention, in some modes, will take advantage of the pressure 
energy in the ram compressed air before it goes through the engine 
compressor. The ram air utilized is at a lower temperature than the 
compressor air and therefore requires less processing than compressor 
bleed air. 
In some cases, the ram compressed inlet air will have sufficient pressure 
to drive the vapor cycle unit, or to operate the unit in the emergency 
electrical power mode. 
Some operational modes for the present invention will jointly use ram 
compressed air with engine compressed bleed air to drive the cabin 
pressurization and cooling equipment, with no requirement for electrical 
power input from the aircraft electrical power system. 
In an emergency mode, the integrated air conditioning/emergency power 
system unit will perform as an electrical power generator. This precludes 
the need to install alternate emergency electrical generating equipment 
(e.g. ram air turbines/generators). The unit, operating in this mode, may 
be powered by bleed air from any functioning engine on the aircraft. 
During supersonic flight, at which time the ram air is hot, the integrated 
air conditioning/emergency power system unit will provide cooling and 
cabin pressurization using bleed air or a combination of electric power 
and bleed air. The integrated air conditioning/emergency power system can 
also be used under these conditions to extract pressure and/or thermal 
energy from the hot bleed air, which can then be either used directly in 
the cabin or passed through the vapor cycle evaporator for further 
cooling. 
During engine bleed extraction for anti-ice purposes, the proposed 
arrangement will extract heat and pressure from the bleed air and convert 
it into usable shaft energy for air conditioning or to produce electrical 
power. This would reduce the pressure and temperature of the bleed air to 
parameters usable for anti-ice and may replace the function of, and in 
some cases, preclude the need for the air pre-cooler and the pressure 
regulator which is presently used on conventional installations. 
The integrated air conditioning/emergency power system arrangement provides 
a compact means of conveying the heat from the cabin recirculation air to 
the fuel mass. In this mode, the unit would be driven either by bleed air, 
the electric motor, or a combination of the two. 
With the system of the present invention, any aircraft not having an 
auxiliary power unit could be operated using only one type of ground 
support cart and it could be either a pneumatic cart or electrical power 
cart. Use of either cart would allow engine starting or air conditioning 
while on the ground. 
Further areas of applicability of the present invention will become 
apparent from the detailed description provided hereinafter. It should be 
understood however that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are intended for 
purposes of illustration only, since various changes and modifications 
within the spirit and scope of the invention will become apparent to those 
skilled in the art from this detailed description.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to FIGS. 1 and 2, the integrated air conditioning and 
emergency power system according to the present invention will be 
described. The system of the present invention is utilized in combination 
with an aircraft engine 10. The engine 10 includes an inlet end 12 and a 
nozzle end 14. The inlet end 12 is provided with an inlet diffuser 16 
which reduces supersonic air to subsonic air for delivery to a compressor 
18. The compressor 18 is driven by a shaft 20 which is connected to a 
turbine 22. A combustion section 24 is disposed between the compressor 18 
and the turbine 22. Compressed air from the compressor 18 is delivered to 
the combustion section 24 where the compressed air is mixed with fuel and 
ignited. The combustion gases from the combustion section 24 are then 
delivered to the turbine 22 for driving the turbine blades which thereby 
turn shaft 20. The exhaust gases from the turbine 22 are then delivered 
through a supersonic expansion nozzle 26 disposed in the nozzle end 14 of 
the engine 10. 
The system of the present invention utilizes a ram air port 30 in 
communication with the inlet end 12 of the engine 10. In addition, a bleed 
air port 32 is provided in communication with the compressor 18. The bleed 
air port 32 communicates via a passage 34 with a bleed air manifold 36 
which is in fluid communication with bleed air from the other engines. A 
check valve 38 is disposed in the passage 34 for preventing high pressure 
bleed air from the bleed air manifold 36 from reversing flow in the 
passage 34. 
A passage 40 is provided between the bleed air manifold 36 and an air 
turbine 42. A first valve 44 is provided in the passage 40 for delivering 
bleed air from the bleed air manifold 36 to the passage 40. A second valve 
46 is provided for connecting the passage 40 with the air turbine 42. A 
third valve 48 is provided in a passage 50 which is connected between the 
fluid passage 40 and a passage 52 which communicates with an air 
compressor 54. A fourth valve 56 is disposed in the passage 52 for 
connecting the passage 52 with the ram air port 30. A fifth valve 57 is 
provided for connecting the passage 52 with the air compressor 54. 
Exhaust air from the air turbine 42 escapes through a passage 60 which 
communicates with a sixth valve 62 which selectively provides heated air 
for anti-ice systems or exhausts the air overboard. The passage 60 also 
communicates with a mixing valve 64 which mixes the air turbine exhaust 
air with exhaust air from the air compressor 54. The air mixed by the 
mixing valve 64 is selectively directed to a vapor cycle evaporator 70 of 
an environmental control system 71 via a passage 72 which is then remixed 
with air from a passage 74 for providing conditioned, pressurized air to 
the aircraft cabin via a passage 76. 
The vapor cycle environmental control system 71 includes a vapor-cycle 
compressor 80 drivingly connected to the air turbine 42. The vapor-cycle 
compressor 80 delivers pressurized refrigerant to the vapor cycle 
evaporator 70 and to a cabin evaporator 82 via refrigerant passages 84, 
86. A refrigerant passage 90 is connected between the cabin evaporator 82 
and the condenser 92. An expansion valve 94 is disposed in the refrigerant 
passage 90. A refrigerant passage 96 is disposed between the condenser 92 
and the vapor-cycle compressor 80. 
As discussed previously, the vapor cycle evaporator 70 is provided for 
cooling bleed air and ram air which is exhausted from the air turbine 42 
and the air compressor 54 so that the high pressure air can be utilized 
for pressurizing the air craft cabin. A recirculation fan 100 is provided 
for recirculating air from inside the aircraft cabin through the cabin 
evaporator 82 in order to re-cool the cabin air. The condenser 92 removes 
heat from the refrigerant utilized in the environmental control system 71 
and conveys the heat to a fuel heat sink 101. 
A motor/generator 104 is drivingly connected to the air turbine 42 as well 
as the air compressor 54 and the vapor-cycle compressor 80. The 
motor/generator 104 is capable of drawing electricity from a primary power 
system 108 and of generating electricity which is delivered to the primary 
power system 108. A bidirectional electric power converter 106 is 
connected between motor/generator 104 and the primary power system 108. 
Motor/generator 104 is capable of driving the air compressor 54 and the 
vapor-cycle compressor 80 in a motor-operating mode and is also capable of 
generating electricity when driven by the air turbine 42. Electricity 
which is generated by the motor/generator 104 is delivered to the primary 
power system 108 and is either stored or delivered to other aircraft 
systems. 
With reference to FIG. 2, the integrated air conditioning and environmental 
control system of the present invention is provided with an environmental 
system controller 110 which receives data from an air data computer 112. 
An electrical power source load management computer 114 is provided for 
monitoring where power is delivered from the aircraft primary power system 
108. 
The environmental system controller 110 controls the operation of each of 
the valves V1-V6 as well as the recirculation fan 100 based upon data 
received from the air data computer 112. The air data computer 112 
monitors the temperature, humidity, and pressure of the cabin air. 
With reference to FIGS. 1 and 2, the operational modes of the present 
invention will now be described. 
MODE 1--NORMAL AIR CONDITIONING DURING CRUISE 
Shaft power extraction from the engine is usually much more efficient than 
bleed air extraction and, during cruise, excess electrical energy is 
available from the aircraft primary electrical power system 108. 
Therefore, in this mode, the motor/generator 104 is driven from the 
aircraft primary electrical power system 108 through the bidirectional 
electrical power converter 106 which allows any frequency electrical power 
to drive the motor/generator 104 at any selected or programmed speed or 
torque up to the rated capacity of the converter 106 or the 
motor/generator 104. The motor/generator 104 then powers the air 
compressor 54. The air compressor 54 takes ram air from the ram air port 
30 through open valves 56, 57 and compresses it to the required 
cabin/pressurization level. At supersonic cruise conditions, little 
pressurization is required. The air exiting the compressor 54 is then 
divided as required by the mixing valve 64 and passed through the vapor 
cycle evaporator 70 for cooling to the correct cabin temperature. 
The vapor cycle compressor 80 is also powered by the motor/generator 104. 
In the event that electrical power is not available, due to failure or 
other demands, the shaft may be driven entirely or partially in any 
combination with the motor/generator 104 and through the use of main 
engine compressor bleed air extraction via bleed air port 32 operating on 
the air turbine 42. Exhaust from the turbine 42 may be discharged 
overboard via valve 62 or used to augment the cabin pressurization process 
via mixing valve 64. 
MODE 2--NORMAL AIR CONDITIONING DURING CRUISE (bleed air only) 
During some flight modes, demands for the electric power resources may 
reach a level at which it is expedient to operate the environmental 
control system under engine bleed power only. In this mode, bleed air will 
be extracted from the bleed air ports 38 of engine compressor 18 through 
open valve 44. The bleed air manifold 36 shown in FIG. 1 allows any 
operating engine to supply bleed air to any integrated air 
conditioning/environmental control system unit. The bleed air will pass 
through open valve 46 and power the turbine 42. The exhaust from the 
turbine 42 then passes through the mixer valve 64 to be combined with the 
other processed air either upstream or downstream of the vapor cycle 
evaporator 70. The shaft 116 of the integrated air 
conditioning/environmental control system is thus driven entirely by means 
of engine bleed air in this mode. Air from the ram air port 30 is directed 
through open valves 56 and 57 and compressed by the air compressor 54. 
This compressed air is then used in the normal manner through mixing and 
cooling in the vapor cycle evaporator 70 to cool and pressurize the 
aircraft cabin. In all of the cooling modes, the cabin evaporator 82 is 
used to cool the recirculated cabin air. 
Furthermore, in this mode of operation, available electrical power may be 
used to drive the motor/generator 104 in the motor mode to supplement the 
engine bleed air to power the integrated air conditioning/environment 
control system unit, or conversely, excess bleed air power may be 
extracted and used to drive the motor/generator 104 as a generator to 
augment the electrical power for use elsewhere in the aircraft operation. 
MODE 3--EMERGENCY ELECTRICAL POWER OPERATION/ENGINE OUT 
During flight, an engine 10 may be shut down, depriving the electrical 
power system of the generating capacity mounted on the inoperative engine. 
Also, any of the engine driven electrical power generators may fail. 
During emergencies which result in a shortage of electrical power, bleed 
air from any engine may be directed from the bleed air port 32 to any of 
the integrated air conditioning/environmental control system modules to 
drive the air turbine 42 and thus the motor/generator 104 as a generator 
to provide emergency electrical power. This can be done concurrently with 
operation of the vapor cycle cooling function as long as sufficient bleed 
air power is available. 
MODE 4--BLEED AIR MODULATION DURING ANTI-ICE FUNCTION 
Ice protection will be required for supersonic transport operations during 
some flight regimes. The anti-ice provisions may be strictly based on a 
conventional bleed air system concept, or bleed air in conjunction with 
electrical thermal heaters. In any event, the bleed air is usually too 
high in temperature and pressure for immediate use for anti-ice purposes 
and is normally pre-processed through a pre-cooler to reduce the 
temperature, and through a pressure regulator to reduce the pressure. Both 
of these components accomplish their function by wasting or discarding 
valuable thermal energy. With the integrated air conditioning/environment 
control system according to the present invention, energy is removed from 
the bleed air as it is first passed through the air turbine 42 prior to 
being utilized in the anti-ice function. This energy can be used to drive 
the motor/generator 104 as a generator and then utilized as electrical 
power to supplement the anti-ice function and the electrical heaters. 
Alternately, the shaft energy may be used to drive the vapor cycle 
compressor 80, or may be used as electricity for any other task. The 
result is that the cost and weight of the pre-cooler and pressure 
regulator valve is avoided in the design, and energy is not wasted. 
MODE 5--RAM AIR ONLY OPERATION 
Under some operational conditions, the inlet pressure from ram air port 30 
will be sufficient to drive the integrated air conditioning/environment 
control system without the need for compressor bleed air. The compressed 
ram air is directed through ram air port 30, through open valves 57, 48, 
and 46 to power the air turbine 42. The valve 56 would be closed. The 
power thus generated could be used to power the vapor cycle air 
compressor, the motor/generator 104 or both. This provides a particular 
advantage in the case of a failed engine, or malfunctioning inlet center 
body in which case the spillage of air from the inlet 12 could be 
minimized and drag could be reduced by this alternate use of the inlet 
air. 
In the system of the present invention, the electrical power source load 
management computer 114 and environmental system controller 110 operate in 
conjunction with one another for determining which operating mode should 
be employed based upon aircraft electrical power usage requirements as 
well as environmental control system requirements. Environmental system 
controller 110 is operable to open and close valves V1-V6 as well as 
selectively operating recirculation fan 100 based upon data received from 
air data computer 112. 
The integrated air conditioning/environment control system of the present 
invention may be used or applied in any situation in which a multiplicity 
of types of energy conversion is desired to be accomplished at a single 
location. Power flow may be from the unit to the primary power system, or 
from the primary power system to the unit. In addition, the common 
shaft-mounted equipment is not limited to those previously described, but 
may include such components as pumps for water or hydraulic systems, or 
liquid phase turbines. 
It is anticipated that a combuster unit could be integrated into the design 
of the present invention so that the proposed unit would resemble a gas 
turbine auxiliary power unit (APU) similar to those in use on present 
transport aircraft, but with the addition of the electric motor function 
and the vapor cycle compressor. Such a system would differ from the 
present APU also in the ability of the present invention to provide 
compressed air when motored by the electric motor, and to be driven 
alternately by bleed air acting on the power turbine. 
It is anticipated that the system of the present invention may have other 
applications including stationary operation in refinery or processing 
plants, portable operation as an aircraft support ground power unit, other 
mobile applications such as on ocean ships, military armored vehicles, and 
heavy trucks or buses. In the fixed location application, such as in a 
petroleum refinery or oil production platform, the unit could be used to 
expand and condense natural gas products, while producing electrical power 
simultaneously. This usage would be similar to the use of the 
turbo-expanded device presently used for this purpose, but with the 
addition of the electric power generator and possibly a vapor cycle unit 
to reduce the number of passes required for the unit to condense the gas 
to a liquid for easy transport. In the same application, a pump could be 
added to re-inject the separated water into the ground. 
Present day fighter aircraft require at least three different types (and 
often four) of ground support carts to service the aircraft while they are 
on the ground. These include pneumatic, air conditioning, hydraulic, and 
electrical. This presents a great logistic challenge when the aircraft are 
deployed away from the base. With the use of the integrated air 
conditioning/environment control system concept, it is conceivable that 
the number of carts could be reduced to one type. A single integrated air 
conditioning/emergency power system unit could supply the chilled air for 
the environment control system function as well as the compressed air for 
pneumatics requirements, and with the addition of a hydraulic pump to the 
integrated air conditioning/emergency power system unit, it could also 
provide the hydraulic pressure required for an aircraft hydraulic system 
ground functional readiness check. 
The system of the present invention could have several shipboard 
applications. In one scheme, the unit could be used to provide local 
compressed air and/or air conditioning while being powered from the 
distributed electrical power system. This system would obviate the need to 
provide costly duplicate distribution systems for the pneumatic and air 
conditioning systems in addition to the electrical power systems. 
Conversely, survivability in battle could be enhanced in the case where 
ship-wide distribution of two or three types of power have been installed. 
In this case, interruption of the electric power (due to battle damage) to 
a portion of the ship could be corrected by using the integrated air 
conditioning/emergency power system unit, powered by the distributed 
compressed air system, to provide local electrical service. 
The system of the present invention permits a single line replaceable unit 
to process air from the engine inlet diffuser or any other ram/air capture 
device of a supersonic aircraft and use this processed air to pressurize 
and cool the cabin and avionic equipment. The present invention also uses 
engine bleed air in combination with the inlet air to cool and pressurize 
the cabin. Furthermore, engine bleed air from any operating engine is 
utilized to provide emergency electric power. The system of the present 
invention can use electrical power only or electrical power in combination 
with engine bleed air to cool and pressurize the cabin. This system also 
provides a means to cool recirculated air in the cabin, either using 
electrical power or a combination of electrical power and bleed air. This 
system also uses cool engine bleed air to reduce the pressure of the bleed 
air for utilities (i.e., anti-ice) while simultaneously generating 
electrical power, instead of wasting the heat and pressure energy in a 
heat exchanger. 
The integrated air conditioning/emergency power system according to the 
present invention improves the operation of the supersonic transport on 
the ground. The system of the present invention facilitates the 
elimination of the gas turbine auxiliary power unit presently used on 
subsonic transports. The addition of a combuster to the integrated air 
conditioning/emergency power system unit would return the APU function to 
the aircraft, in that the integrated air conditioning/emergency power 
system would be a battery-started engine providing air conditioning during 
ground operations and electrical power to start the main engines. This 
would be achieved at a fraction of the cost and weight of a separate APU. 
Even without the combuster, the integrated air conditioning/emergency power 
system of the present invention would enhance ground operations. For 
example, for an aircraft which is provided with an electric starter to 
start the main engines, the integrated air conditioning/emergency power 
system unit, can be utilized with pneumatic ground power which could be 
connected to drive the turbine to cause the motor/generator 104 to operate 
in the generator mode and provide electric power to start the engine. In 
addition, except during a brief interval during high power consumption 
during engine starting, the integrated air conditioning/emergency power 
system unit could provide the cabin cooling resource while being powered 
either electrically or pneumatically. In short, the integrated air 
conditioning/emergency power system unit will allow any aircraft that is 
equipped with it to operate on the ground using only one type of ground 
support cart. 
Although the invention has been described with particular reference to 
certain embodiments thereof, variations and modifications can be effected 
within the spirit and scope of the following claims.