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Патент USA US2412110

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Dec. 3, 1946.
2,412,110
L. A. WILLIAMS, JR
AIR CONDITIONING APPARATUS FOR AIRCRAFT
Filed Feb. 4, 1943
s Sheets-Shed 1
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£5
M
Dec. 3, 1946.
2,412,110
L. A. WILLIAMS, JR
AIR CONDITIONING APPARATUS FOR AIRCRAFT
3 Sheets-Sheet 2
Filed Feb. 4, 1943
WN
\A!-
6'(mil.
Dec. 3, 1946.
1.. A. WILLIAMS, JR
2,412,110
AIR coumnonme APPARATUS FOR AIRCRAFT
Filed Feb. 4, 1943
$26
3 Sheets-Sheet 3
Patented Dec. 3, 1946~
' 2,412,110
UNITED STATES PATENT OFFICEv
2,412,110
AIR CONDITIONING APPARATUS FOR
AIRCRAFT
Lynn A. Williams, Jr., North?eld, 111., assignor
to Stewart-Warner Corporation, Chicago, 111.,
a corporation of Virginia
Application February 4, 1943, Serial No. 474,632
21 Claims. (Cl. 257—3)
1
2
My invention relates generally to an air con
ditioning apparatus for use on aircraft, and more
fuselage is substantially .sealed and is super
charged by a blower l6 which receives air from
particularly to mechanism for maintaining the
a pipe [8 leading to a ram opening 20 at the
air in the cabin of an airplane at the desired
leading edge of the wing. With the blower is
temperature and pressure.
in operating, air is forced through a heat exchanger
It is an object of my invention to provide an
22 to a duct 24 leading to the supercharged cabin
improved means for optionally heating or cooling
within the airplane fuselage, the pressure in the
the air supplied to supercharged aircraft cabins.
cabin being controlled by a cabin pressure regu
A further object is to provide an improved
lating valve of any suitable type indicated dia
heating apparatus and improved controls there 10 grammatically at 26.
for, to the end that the apparatus may be caused
In order to provide ventilating air for the cabin
to operate e?iciently under a wide variety of dif
at low levels where supercharging is not neces~
ferent atmospheric operating conditions.
sary, the blower I6 is by-passed by a conduit 28
A further object is to provide improved appa
having a check valve 30. This check valve per
ratus for supplying cool air to an airplane cabin. , mits air to flow through the by-pass 28 from the
A further object is to provide an improved
inlet pipe l8 to the heat exchanger 22 whenever
heating apparatus with improved controls,
the pressure in the pipe I8 rises substantially
whereby the apparatus will operate e?iciently at
above the pressure at the outlet of the blower IS.
high as well as low altitudes.
The check valve 30 prevents ?ow in the reverse
A further object is to provide an improved air 20 direction, however.
heating and cooling system for aircraft which
A second ram opening 32 located at the lead
has few moving parts, which is light in weight,
ing edge of the wing is connected to a duct 34
which is e?icient and durable, and which may be
which passes air through the heat exchanger 22
economically manufactured.
in heat exchange relation to the air passed there
Other objects will appear from the following - through by the blower [6 or by-pass 28. Air
description, reference being had to the accom
from the duct 34, after passing the heat ex
panying drawings, in which:
changer 22, continues to flow through a tailpipe
Fig. 1 is a diagrammatic view of one form the
36 leading to an outlet in the air stream.
apparatus may take, illustrated generally in plan
Whenever the airplane is flying at compara
section as installed in the wing of an airplane;
tively high altitudes and the blower I6 is oper
Fig. 2 is a view similar to Fig. 1 but showing
ating. air will be taken into the blower at slightly
an alternative air conditioning arrangement em
above atmospheric pressure. This air will be
bodying the present invention; and
compressed in the blower and will issue there
- Fig. 3 is a view similar to Fig. 2 illustrating
from at an elevated pressure and temperature.‘
still another alternative form the invention may
If the air passes directly from the blower to the
cabin and the cabin is maintained above atmos
pheric pressure, it will be apparent that the air
thus passed to the cabin will be considerably
take.
.
.
Maintaining the temperature of the air in an
airplane cabin relatively constant and at a com
fortable level presents many di?iculties because
of the wide variations in atmospheric tempera
ture and pressure which are encountered while
the airplane is in ?ight. These di?iculties are
augmented when the cabin is supercharged. In
the latter case air is heated, due to its compres
sion, by the supercharger before being passed to
the airplane cabin. As will appear hereafter,
this heating eifect produced by the supercharger
above atmospheric temperature. Usually at high
40
altitudes it is relatively cold and this heating ef
fect is not objectionable. Under some conditions,
however, the heating effect thus produced is more
than desirable, and this excess heat is removed
from the system by passing air at atmospheric
temperature through the duct 34’ across the heat
exchanger 22, thus cooling the air before it
reaches the cabin in the fuselage 12.
can be used for cooling the plane when the- air
In order to heat air passed from the blower I6
craft is cruising at low altitudes in hot weather.
,to the cabin, I have placed a small internal com
In Fig. 1 of the drawings I have illustrated 50 bustion heater indicated generally by the numeral
diagrammatically the leading edge portion III of '
38 in the duct 34. This heater includes a fuel
an airplane wing near the root section where it
mixing tube 40 connected with a combustion
joins the airplane fuselage indicated by the nu
chamber 42. Liquid fuel, such as gasoline, is
meral 12, the wing and the fuselage being sepa
supplied from a suitable fuel tank 44 to the'fuel
rated by the cabin wall I l. The cabin within the 55 mixing tube 40 through a pipe 46, the upper
9,419,110
3
4
portion of the fuel tank being maintained under
slight pressure by virtue of a pipe 46 which has
the numerals 62, 64 and 66. These proportioning
an opening facing the ram 62, while the tube
#6 may have a similar opening facing in the op
posite direction to form a fuel jet aperture with
in the mixing tube 46. The now of fuel through
the pipe 46 is controlled by a solenoid valve 66
which may be of conventional type in which the
,valve is held in closed position by resilient means '
and is opened whenever the solenoid is ener 10
gized.
motors are standard articles of commerce, one
type being supplied by the Barber-Colman Com
pany of Rockford, Illinois, and although other
types may be used, it will be assumed for the
purpose of illustration that the control motors
62, 64 and 66 are “Barber-Colman" controllers.
In general, the mode of operation of these
controllers is such that they automatically con
tinuously cause the valve or damper to which
they are connected to assume a desired position
so as to maintain constant some certain tempera
ture or barometric pressure. As an example, the
motor 66 is of the series wound type and is con
nected to drive the input shaft of a speed re
duction gear train 66. The output shaft ‘I6 of
Within the combustion chamber 42 is an igniter
62 of the hot resistance wire type. one terminal
of the igniter being illustrated as grounded while
the other terminal is connected through a tem
perature responsive igniter cutout switch 64 to a
conductor 56. One terminal of the winding of
this gear train revolves at low speed and high
torque and is connected to the damper D. The
the solenoid valve 66 is likewise connected with
output shaft is also connected to the swinging
the conductor 66, while the other terminal of this
winding is connected to ground through a tem 20 arm 12 of a variable resistor, the arm at its free
perature responsive overheat switch 56. As will
end contacting a resistance coil ‘I4. One of the
appear presently, the conductor 46 is connected
motor armature brushes is, connected by a wire
‘I6 to a line ‘I6 leading to one side of the air
to a source of current inv order that the heater
may operate.
craft storage battery 66. This wire ‘I6 is also
The heater, per se, does not constitute a part 25 connected to the swinging arm 12 by a conductor
62. The other of the armature brushes is con
of my invention, but may be considered as of the
type fully disclosed in the copending applica
nected to the center of a split field, the two field
coils being indicated by the numerals 64 and 66.
tion of Henry J. DeN. McCollum, Serial 436,090,
The above described portion of the controller
?led March 25, 1942.
.
Some heaters of this‘ type do not operate eil'ec 30 comprises what is generally referred to as the
receiving end of the circuit. The sending end
tively at extremely low barometric pressures and
therefore should be supercharged for high alti
of this circuit is shown to the left of the cabin
tude operation. The arrangement shown in Fig.
wall and comprises a thermostatic switch made
1 accomplishes such supercharging action, as
up of a bimetal strip 66 which at its free end is
will be pointed out presently. Other types of 85 equipped with upper and lower contacts 96 and
92, respectively. These contacts are so arranged
heaters, however, will operate effectively at any
that when the strip 66 ?exes upwardly the con
altitude at which an airplane can ?y. If a heater
tact 96 will be brought against a contact 64 con
of this latter type is used, certain portions of
the apparatus shown in Fig. 1 may be omitted
nected by a conductor 96 to the outer end of the
from the system, as will appear hereafter.
40 field coil 66. Similarly, downward movement of
the bimetal strip 66 brings the contact 92 against
The heater 26 receives its air for combustion
through the duct 64, the ?ow of air through this
a fixed contact 96 connected by a conductor I66
duct being controlled by a damper or valve A of
to the outer end of the ?eld coil 64. The bi
the butter?y type.
metal strip 66 is biased in an upwardly direction '
The air in the duct is divided, a portion of this 45 to a varying degree by a coil spring I62 con
air passing through the heater 66 to be mixed
nected to the upper surface of the bimetal strip
66, the upper end of the spring being connected
with fuel and burned within the combustion
to a ?oating armature I64 located within a sole
chamber 42, the hot products of combustion
noid I66. This solenoid is connected by a wire
issuing therefrom and mixing with another por
tion of the air which flows around the heater. 50 I66 to the proper end of. the resistance element
14. In the interest of simplicity of illustration,
The hot products of combustion mixed with addi
the opposite end of the solenoid I66 and the bi
tional air ?ow rearwardly across the tubes in
metal strip 66 are shown as grounded, as is one
the heat exchanger 22 and issue from the tail
end of the battery 66, it being appreciated of
pipe 66. This tailpipe is equipped with a valve
3 which can be regulated in conjunction with 55 course that a return circuit other than the
ground can be used if desired.
the valve A in a manner to appear presently, to
A controller as above described operates in
control‘the pressure of the air at the heater 66
the following manner. If the bimetal strip 66 is
and the rate of now of air through the duct 64.
so positioned that an‘ increase in temperature will
If the heater is of the type which requires
'supercharging in order to operate properly at 60 cause it to ?ex downwardly, it will be seen that
such a temperature increase will bring the con
high altitudes, it receives air for high altitude
~ operation through a branch duct or conduit 66
I leading from the blower I6 to the duct 34, the
conduit being connected to the duct at a posi
,
tact 92 against the contact 96. This establishes
a circuit from the battery 66 through the con
nectors 16, ‘I6 and 62 with the swinging variable
tion between the valve A and the heater 66. This 65 resistor arm 12 and with one end of the arma
ture 62. The circuit continues through the ar
branch conduit is equipped with a valve 0 which
mature, through the ?eld winding 64, and by
can be regulated in conjunction with the valve
way of the wire I66, contacts 96 and 92 to
,A to determine whether the heater receives air
for ‘combustion from the ram 62 or from the
ground. The motor therefore will run in one
blower I6.v
'
70 direction. In the present instance this direc
, The rate of now of ventilating air through
tion is such as to cause the valve D to swing
,the duct 24 is regulated by a damper D which
toward closed position.
serves a purpose to be described presently.
'
At the same time the motor circuit is energized
The valves A, B and D are operated by small 1
as above described, the current will ?ow through
'proportioning motors indicated respectively by 75 the resistor arm ‘I2, a portion of the resistance
2,412,110
5
coil 14, through the conductor Ill and solenoid
I06 to ground. thus
the solenoid I05
which tends to move the armature I04 upwardly,
thus tightening the spring I02. As the motor
continues to operate when connected in the man
ner above described, rotation of the shaft ‘II
will swing the damper D toward closed position
move toward closed position. A wire II2 leading
.from the battery line ‘I0 leads to one end of the
motor armature 62 and to the swinging arm II4
of the variable resistor Hi, the coil of this re
sistor being connected through a bimetal thermo
stat III with the solenoid coil I20. The thermo
stat IIO, for a reason to appear presently, is
adjusted so as to be closed whenever the tem
perature drops below 75°. As in the previous ex
ample, .one of the ?eld coils I22 is connected to
andwill alsomove theresistorarm ‘l2inthe
same direction, thus decreasing the resistance
of the variable resistor ‘I4. The decrease in re
sistance thus brought about permits a greater
the lower contact I24 in the sending unit, while
current to flow through the solenoid coil I06,
the other ?eld coil I26 is connected to the upper
with the result that the armature I04 is moved
contact I28. The above system is so arranged
outwardly more strongly, thereby stretching the
that a decrease in temperature in the cabin tends
spring I02 and placing a greater bias upon the
to cause the bimetal strip I I0 to ?ex downwardly,
bimetal strip 08.‘ After the motor has continued
thus establishing a circuit, through the ?eld coil
to operate for the proper length of time the
I22 and armature 62. This causes the motor to
attraction of the solenoid Ili for the armature
run so that the valve A is swung toward open
I04 will overcome the temperature bias of the
position, whereas an increase in cabin tempera
bimetal strip 08 and cause the strip to ?ex away 20 ture causes the bimetal strip IIO to ?ex up
from the contact 08 toward the contact 94.
' wardly thereby establishing the circuit through
When the contact 00 is brought against the con
the armature 62 and ?eld coil I26 with the result
tact 94, a circuit is established through the other
that the damper A is moved toward closed posi- '
?eld coil 36, with the result that the motor 66
tion.
rotates in the opposite direction, thus tending to 25
The sending unit also includes a second elec
swing the damper D toward open position while
tromagnet I30 grounded at one end and con
also reducing the resistance of the variable re
nected at its other end to a ?xed contact I32
sistor 14. The reduction in resistance thus
located adjacent a contact I34 moved under the
brought about decreases the strength of the
in?uence of an aneroid element I36, the contact
magnetic ?eld in the solenoid I06, thereby re 30 I34 being connected to the battery line ‘I0 by a
ducing the upward bias on the bimetal strip 00.
wire I30. The bellows, which elongates with a
When the magnetic bias has been reduced some
decrease in barometric pressure, is so adjusted
certain amount, the bimetal strip 80 will be
in the present instance as to close the contacts
able to pull the contact 90 away from the con
I34 and I32 at an altitude of approximately 18,000
tact 04. The motor therefore continuously ?uc 35 feet, thus establishing a circuit through the elec
tuates in its direction of movement so as to
tromagnet I30. The electromagnet I30 is posi
position the damper D at approximately some
tioned above the bimetal strip H0 and acts upon
predetermined position depending upon the tem
an armature I40 secured to the upper surface
perature of the air surrounding the bimetal strip
thereof so as to cause the bimetal strip to move
30, it being appreciated that an increase in the
upwardly. The strength of the magnetic ?eld
temperature surrounding the bimetal strip will
cause the bimetal strip to ?ex downwardly more
strongly, thus requiring that a greater propor
tion of the resistor ‘I4 be removed from the cir
cuit before the contact 02 will separate from
the contact 90.
\
Controllers of this type can be wired so as to
cause a valve either to open or close, depending
upon an increase or decrease in temperature, the
controller 66 being connected to the valve D in
such manner that an increase in temperature
within the airplane cabin will tend to cause the
valve D to close, while a decrease in temperature
inthecabinwillbringaboutanopeningofthe
valve D.
,
ClosingofthevalveDtendstodivertthe
?ow in the conduit 24 through a rotary expander
240 (see Figs. 2 and 3). The inlet side of this
rotary expander is connected to the conduit 24
upstream of the valve D by a pipe 242, while
the outlet side of the rotary expander is con
nected to the conduit 24 d
of the valve
Dbyapipe 244. Inthepresentinstancethe
rotary expander, which is of the turbine type,
drives a generator 246 connected to a resistance
type energy dissipating unit 240. The operation
of this rotary expander in conjunction with the
valve D will be explained presently.
The controller 02 connected to the valve A
issowiredthatadecreaseinthecabintem
perature will cause the bimetal strip III- to ?ex
downwardly, thereby causing the motor 62 to
runin such directionthatthevalveAisswung
developed by the electromagnet I 30 is su?icient
to overcome any tendency of the strip IIII to
?ex downwardly, and thereby maintains the bi
metal strip in its uppermost position whenever
the electromagnet is energized. This upward
movement of the bimetal strip closes the circuit
through the contact I20 to the ?eld coil I26, with
the result that the valve A is swung completely
to its closed position and held in this position
whenever the aircraft is over 18,000 feet, or some
other predetermined altitude to which the pres
Sure switch is set.
The contact I32 is also connected by means of
a conductor I42 with a stalling motor I44, the
shaft of which controls the valve C. This motor
is so arranged that whenever it is not energized
the valve C will be resiliently held in closed D0
sition, whereas whenever the motor I44 is ener
gizedthevalvecwillbeswungintoitsopenpo
sition. It is apparent, therefore, that whenever
the contact I34 is brought against the contact
I32 so as to swing the valve A into its clowd
position, the circuit thus established will simul-'
taneously swing the valve 0 into its open posi
tion. Conversely, whenever the contact I34 is
separated from the contact I32 so as to place the
valve A under the in?uence of the cabin tem
perature thermostat, the valve C will be swung
1 into its closed position.
The valve 13 is controlled by the motor 64 which
receives its current through a line I46 connect
ed to the main battery ‘cable ‘I0, this line I40
being connected to one end of the motor arma
ture and to the swinging resistor arm I 40. As in
toward open position. Conversely, an increase
in cabin temperature will cause the valve A to 75 the previous example, one end of the resistance
9,418,110
coil I88 is connected to ground through the sole
8.
cabin will receive its ventilating air through the
ram opening 28, the conduit I8, the ivy-pass 28,
the passages through the heat exchanger 22, and
the duct 24, this air passing outwardly through
noid I82, while the two field coils I84 and T88 are
connected respectively to contacts I88 and I88.
The contact-carrying strip I82, which in the pre
the cabin pressure control valve‘ 28 or through
vious examples is a bimetal temperature-sensi
other ventilator openings located within the air
tive strip, is in the present instance merely a
plane cabin.
resilient metal member biased upwardly by an
Under these moderate temperature, low alti
aneroid bellows I84 at decreased barometric
tude conditions the heater "will not be ener
pressure, the strip I82 and the bellows being en
closed within a sealed chamber I88 connected 10 gized, since the contact I12 does not touch the
contact I18. Since the air conditioning system is
by a tube I88 to the tailpipe 88 in a position above
used neither for cooling nor heating, the podtion
the valve B.
ing of the valves A and B is unimportant and
The wire 88 connected to the solenoid valve 88
therefore need not be described. The valve 0
and the igniter 82, leads to a contact I18 which
is brought against a contact I12 on a bimetal 15 remains in its closed position since, as has been
pointed out,‘ this valve does not open until its
strip I18 whenever the cabin temperature drops
motor I44 is energized by closing of the contacts
below approximately 70°. The bimetal strip I18
I82 and I84 at 18,000 feet. The valve D ?ts com
is in turn connected to the battery line 18, and
paratively loosely within the duct 24, so that even
therefore the heater operates whenever the cabin
temperature falls below approximately 70° or 20 when this valve is in its’ closed position it will
offer comparatively little restriction to the flow
some other temperature to which the device is
of ventilating air, inasmuch as the ventilating air
preset. 'At the same time the bimetal strip brings
circulation is at comparatively low velocity when
the contact I12 against the contact I18, it also
the blower I8 is not operating.
closes another set of contacts, I14 on the bi
From the above it is apparent that below 12,000
metal strip and I18 associated therewith. This
feet when the temperature is between 70° and 78°
‘contact I18 is connected to the motor of the
the apparatus functions purely as a ventilating
blower I8 by a wire I18, the other side of the
system.
>
:motor circuit being grounded. A set of contacts
I88 and ‘I82 arranged similar to the contacts I14
Low altitude, cold weather operation of the
and I18 are disposed on the opposite side of the 30
system
bimetal strip I18. They are so spaced that heat
As
the
temperature
decreases to a point below
ing of the bimetal strip I18 to 78° or above will
70°, the free end of the bimetal strip I18 will
bring the contact I88 into engagement with the
move to the right, thus bringing the contact I12
contact I82. A wire I84 leads from the contact
I82 to the wire I18, with the result that the 35 against the contact I18 and the contact I14
against the contact I18. The making of these
blower I8 will run whenever the temperature
connections
establishes a power circuit through
within the cabin is below 70° or above 78°.
the wire I18 to the blower I8, and another power
The blower motor circuit also includes a Pres- I
circuit to the line 88, the solenoid 88 and the
sure operated aneroid type switch I88 located
outside ‘the cabin, this switch being connected 40 igniter 82. Openingv of the solenoid valve permits
fuel to ?ow to the heater 88, where it is mixed
between the line I18 and the power line 18. The
with air to form a combustible mixture, this mix
switch I88 in the present instance is adapted to
ture being ignited and burned within the com
close at approximately 12,000 feet altitude and
bustion chamber 42 by the igniter 82. After op
to remain closed at higher altitudes. It is ap
eration of the burner has become established, the
parent, therefore, that the blower I8 will be
switch 84 will open to deenergize the igniter .82.
placed in operation whenever the plane ?ies
Hot products of combustion, therefore, are passed
above 12,000 feet and whenever the cabin tem
through the duct 84 across the heat exchanger 22
perature is below 70° or above '78‘_’. It will be
and out through the tailpipe 88. Meanwhile oper
understood that these particular pressures and
ation of the blower I8 takes air from the duct
temperatures are given for purposes of illustraé
I8 and forces it through the heat exchanger 22,
tion only.
'
through
the duct 24, and into the airplane cabin,
Although in the interest of clarity of illustra
the air eventually escaping through the cabin
tion the mechanism has been shown diagram
pressure control valve 28 or other cabin venti
matically, the several switches being. illustrated
as of the slow moving contact type, it will be ap 55 lators.
The decrease in cabin temperature which closed
preciated that if desired many of these switches
the heater and blower motor circuits also tends
should preferably be of the “micro” or snap con
to de?ect the thermostatic strip 88 upwardly so
tact type, so as to give a fast and positive make
as to establish a circuit from the power line 18
and break to the circuits when the switches op
through the conductor 18 to the positioning motor
erate.
88, originally to the ?eld coil 88. This causes
The operation of the above described air con
the motor 88 to revolve the valve D toward open
ditioning system is for convenience considered
position. As this valve moves toward open posi
according to its functioning at different altitude
tion, resistance will be added to the circuit of the
and temperature conditions.
65 solenoid coil I88 because of the movement of the
Operation ol'the system at low altitude du?na
swinging arm 12 across the resistor element 14
temperate weather
until the decrease in magnetism within the sole
noid I88 permits the armature I84 to move down
At low altitude the pressure operated switch
wardly, thus permitting the contacts 88 and 84 to
I88 will be open, inasmuch as this switch does not
'
close until the airplane rises to approximately 70 be separated.
The characteristics, therefore, of the thermo
12,000 feet. Under these temperate weather con
static strip'88, the solenoid I 88 and the resistor
ditions, which may be considered as between 70°
element 14 are such that at low temperatures the
and 78°, the thermostatic bimetal strip I18 will be
valve D is disposed well toward its open position,
spaced from both the contacts I18 and I82.
Therefore the blower I8 does not operate, and the 78 whereas at higher temperatures the valve D is
2,412,110
.
[located more toward its closed position.- The
-
10
'
regulates the motor 66 in such manner that the
valve D is swung toward closed position whenever
the cabin temperature tends to increase. The
valve D does not oifer appreciable resistance to
the ?ow of air through the duct 24, however, until
valve D therefore ofl'ers considerable restriction
the cabin temperature approaches the top of the
to the flow of air from the blower I6 and diverts
comfort range, that is, 78°. As the temperature
the air through the rotary expander 240. The
tends to rise above 78°, the valve will be swung
ventilating air is therefore compressed into a con
more and more toward its closed position, thereby
dition well above atmospheric pressure between
offering an increasing and appreciable resistance
theblower I6 and the valve D. This‘ compressing
to the ?ow of air through the duct 24.
effect heats the air considerably above atmos
The decrease in cabin temperature which
pheric temperature. vAs it passes through the
brought about starting of the heater and the
heat exchanger, heat is exchanged from the air
blower I6 and which further tends to swing the
issuing from the blower to the air passing through
valve D more toward its open position, also ini
the duct 34, with the resultlthat the ventilating
tially causes the thermostatic strip II 0 to tend
to move downwardly to establish a circuit 15 air flowing from the outlet side of the heat ex;
changer 22 is reduced substantially to atmos
through the-motor 62 by way of the power line
pheric temperature but is under considerable com
‘I8, the wire II 2, the ?eld coil I22, the contact
pression. As the compressed air expands in the
I24, the thermostatic strip I I0, and ground. This
rotary expander and does work therein in rotating
causes the motor 62 to revolve in such direction
the turbine against the restraining effect of the
that the valve A is swung toward its open posi~
generator 246, its ‘temperature is considerably re
tion. Thus, as in the case of the motor 66, the
duced, so that the air ultimately reaching the cab
control system for the motor 62 is so arranged
in is well below atmospheric temperature. The re
that the valve A tends to swing toward open
frigerating effect thus produced reduces the cabin
position at lower temperatures, and conversely‘
temperature well below that of the outside air,
tends to close at higher temperatures.
thereby insuring the comfort of the passengers in
Inasmuch as the output of the heater 38 de
hot weather, the valve D automatically assuming
pends largely upon the amount of air flowing
whatever position is necessary to divert the proper
through the duct 34, it will be seen that moving
amount of air through the rotary expander to se
the valve A toward open position increases the
cure the desired degree of cooling.
heat output of the heater 38, whereas an increase
As the airplane flies from such hot conditions
in cabin temperature tends to swing the valve A
into more temperate weather, the valve D will be
toward closed position, thus decreasing the heat
swung toward open position to reduce the re
output. The amount of heat in the mixture car
frigerating effect. When the cabin temperature
ried across the heat exchanger 22 therefore is
falls below ‘78°, the switch I15 will open thereby
regulated so that more heat will be present to
deenergizing the blower I6,
be transferred to the air passing from the blower
through the duct 34 when the cabin temperature
Operation of the system under temperate weather
is low, whereas less heat will be present when
conditions at medium altitude
the cabin temperature is high.
,
As
the
airplane
rises under temperate weather
The thermostat which controls the motor 62 is
conditions, the surrounding ‘pressure gradually is
set to maintain a cabin temperature somewhat
reduced until the switch I86 is closed at an alti
less than 70°. That is, any tendency of the tem
tude of approximately 12,000 feet. This starts op
perature to rise above this ?gure causes the motor
eration of the blower I6, the cabin pressure being
62 to swing the valve A toward closed position,
regulated by the cabin pressure regulating valve
while any tendency of the cabin temperature to
drop will cause the valve A to be swung toward
26. The blower I6 therefore becomes a cabin
supercharger. Inasmuch as air is taken into the
open position. This control therefore maintains
an even cabin temperature at the preset value.
blower I6 at atmospheric pressure and is passed
If the airplane should move into more temperate
to‘ the cabin in a compressed condition—that is,
the pressure of the air from the outlet side of the
conditions where the heater, even when operat
ing at its lowest level, causes the temperature
within the cabin to rise above approximately 70°,
blower on‘ through the duct 24 and into the cabin
is above atmospheric pressure-considerable heat
ing effect will be produced, since the air is not
permitted to re-expand to atmospheric pressure
contacts I10 and I16, thereby deenerg'izing the
55 until passing outwardly through the cabin pres
heater 38 and the blower I6.
sure regulator 26. The heat exchanger 22, how
Operation at low altitude and high-temperature
ever, acts as an intercooler and' tends to reduce
' Whenever the temperature rises above 78°, the
the temperature of the supercharged air to slight
bimetal strip I15 will be swung to the left against
ly above atmospheric temperature. If at medium
the contact I82, thereby energizing the blower I6. 60 altitude—that is, around 12,000 feet or so-some
Under these high temperature conditions the
additional cooling of the air is desirable, this will
thermostatic switch I I8 will be open, inasmuch as
automatically be accomplished by the motor 66
this switch opens whenever the cabin temeprature
swinging the valve D toward closed position, thus
the bimetal strip I15 will move away from the
rises above 75°. The solenoid I20 therefore can
bringing about a flow of air through the rotary
not receive current, and the bimetal strip IIO, 65 expander 240.
since there is no pull thereon from above, will be
Medium altitude, low temperature operation
de?ected downwardly against the contact I24.
As the temperature at medium altitude drops
This energizes the ?eld coil I22, with the result
below 70°, the bimetal strip I15 will move toward
that the motor 62 holds the valve A in wide open
position. The flow of air through the duct 34 is 70 the right, 'thereby energizing the heater, thus
causing the system to operate much as it does in
therefore comparatively rapid, thus bringing a
cold weather at low altitudes. There is one dif
large quantity of air at atmospheric temperature
ference in the operation, however, between the
into heat exchange relation to the air passing
from the blower I6.
'
medium altitude zone and the low altitude zone,
As has been explained, the bimetal strip 88 75 which is produced by the valve B and motor 64.
2,412,110
11
This motor is controlled by the pressure operated
switch I62 located within the box I66 connected
12
greatly simpli?ed. For instance, it is not neces
sary» to provide the supercharging duct 63‘ or
valve C, since supercharging of the heater will
not be necessary- Since this duct and valve are
the increase in altitude, the aneroid element I64 (II not provided, the motor I44 is of course elimi
nated. as is the barometrically operated switch
will expand, thereby swinging the valve B more
comprised of the elements I32, I34 and I36. Also
toward its closed position. The result is that the
there is no need for the electromagnet I30. When
valve B offers a restriction to the flow of air
through the duct 34 on the outlet side. The ram
these elements are removed from the structure
ming effect at the opening 32 therefore causes the 10 shown, it is apparent that the valve A will open
progressively as the airplane cabin cools, thus
air within the duct 34 to be well above atmos
introducing a larger quantity of air whenever it
pheric pressure. The valve B and motor 64 there
is needed'for burning a greater quantity of fuel.
fore cause more efficient operation of the heater
36 at higher altitudes.
The valve B may be used to advantage even with
15 a heater which does not require supercharging,
High altitude operation 0/ the system
since it will aid in maintaining a higher pressure
As the airplane ascends to higher and higher
within the duct 34. thus increasing the heat out
altitudes, the valve B will be swung more and
put of the heating unit. If this increased output
more toward its closed position so as to offer a
is not necessary, the valve B may be eliminated
progressively greater restriction to the flow of 20 together with the motor 64 and the pressure
air from the tailpipe 36. However, the valve
sensitive control element and its box I66. Such
never completely obstructs the tailpipe 36, since
a system operates in the manner previously de
its diameter is somewhat less than the diameter
scribed, excepting that the duct 34 is never super
of the pipe, so that even when in its position of
charged and the air ?ow through this duct is
maximum obstruction the valve still permits a 25 regulated solely by the valve A.
su?icient flow of air through the duct to permit
In Fig. 2 of the drawings I have shown an
e?icient operation of the heater 36.
‘
alternative arrangement which uses the exhaust
As the plane ?ies still higher, a position is
from an airplane engine located within an en
reached at which the ramming effect at the open
gine naceile I30 for heating the ventilating air,
ing 32, together with the obstructing effect of 30 this engine exhaust being used in place of the
the valve B, is not asuflpcient to bring about 'e?i
heater 36. In Fig. 2, instead of the duct 34 con
cient operation of the heater 38. When this
taining the heater 36, this duct is ‘connected by
point is reached, the aneroid element I36 has ex
a pipe I32 to the engine exhaust pipe I34 so that
panded until the contact I34 is brought against
when the duct I32 is open, a portion of the en
the contact I32. This energizes the electromag 35 gine exhaust will flow therethrough into the duct
net I30 in the manner previously described, which
34 and thence across the heat exchanger 22. The
causes the bimetal strip III) to move upwardly,
duct I32 is equipped with a valve or damper I36
thereby establishing the circuit to the control
supported upon a. pivoting shaft connected in
motor 62 through the ?eld coil I26, regardless of
turn to a swinging arm I36. The valve A is simi
the temperature within the cabin. This causes 40 larly provided with a swinging arm 200, the free
the motor to swing the valve A into its closed
ends of the arms I36 and 230 being pivotally
position and to maintain it in this position as
connected by a link 202. With this arrangement
long as the plane is above 18,000 feet. The closing
the motor 62 rotates the valve I36 as it rotates
of the contacts I32 and I34vwhich energize the
the valve A, the positioning of the valves A and
electromagnet I30 also simultaneously brings
I 36 on their shafts being such that when one of
about energization of the valve motor I44. As
these valves is in closed position, the other is in
has been previously explained, this motor swings
its open position. Thus, whenever the motor 62
the valve C into its open position, thus permitting
swings the valve A from its closed position toward
supercharged air to flow through the by-pass 60
its open position, the valve I 36 will be swung from
into the duct 34. At these high altitudes the
its open position to its closed position. The op
_ valve B is in the position where it affords maxi
eration of this system is essentially the same as
mum obstruction. The flow of air from the super
shown in Fig. 1 excepting that whenever the
charger through the duct 60 therefore builds up
cabin temperature drops below a comfortable
a pressure within the duct 34, since the flow past
level, say 70°, the thermostatic element III! will
the valve B is restricted and the valve A is closed.
operate to move the valve A toward closed po
The heater 36 therefore continues to operate at
sition and the valve I 36 toward open position.
altitudes well above those at which it would ordi
thus decreasing the ?ow of fresh air through the
narily be extinguished if it received'unsuper
duct 34 and increasing the ?ow of exhaust gases.
charged air.
.
The temperature of the gases ?owing over the
It is apparent that the above system provides 60 heat exchanger 22 therefore increases, and more
ventilation for the cabin under all temperature
heat is imparted to the air passing from the
and pressure conditions; further, that when
blower I6 to the cabin I2. If more and more
supercharging is needed this supercharging is
heat isrequired, the valve A will be moved more
provided; also, that the air entering the cabin is
and more toward its closed position, thus moving
heated or cooled when such temperature change
valve I36 more and more toward its open position,
is desired, all of the above operations being ac
thereby increasing the ratio of exhaust gases to
complished fully automatically.
fresh air passed over the heat exchanger 22.
The controls for the above described heating
As in the modification of the previous embodi
system presuppose that the heater 36 will not
ment which‘ uses a heater of the type which does
operate e?lciently at low atmospheric pressures
not require supercharging, it. is not necessary to
if it is adjusted for operation near sea level.
provide the valve B and its associated control
There are available, however, heating units
mechanism. Note, however, that whereas a de
which will operate satisfactorily at any altitude
crease in cabin temperature in the device illusat which airplanes normally ?y. When such a
trated in Fig. 1 causes the damper A to open,
heating unit is used, the controls shown may be
a similar decrease in temperature in the embodi
to the duct 34. The connections are such that as
the pressure within the duct 34' drops because of
2,412,110
13.
14
ment shown in Fig. 2 causes the damper A to
swing toward closed position, and therefore the
thermostat H8 is not necessary. This reversal
of the action of the valve A may be accomplished
simply by positioning the damper A on its shaft
at right angles to the position taken by this ele
ment in Fig. 1, so that when the resistor slider
H4 is in the minimum resistance position .the
damper A in Fig. 2 will be in closed position
whereas the damper A in Fig. 1 will be in open
illustrated in Fig. 3, this element may be formed
Position.
In Fig. 3 I have shown an arrangement similar
to that shown in Fig. 2 excepting that an inter
mediate heat exchanger 2“) is used between the
airplane engine exhaust and the duct 34. In
the modi?cation shown in Fig. 3, exhaust from
the engine located within the nacelle I90 passes
into an exhaust pipe 2l2 leading to the heat ex
changer 2l0. From the heat exchanger the ex
haust passes overboard to a tailpipe 2i 4. Air to
be heated is taken in through a ram opening 2 l6
located at the leading edge of the wing, this air
passing through a duct H8 ‘and across the heat
exchanger 2l_ll, thus absorbing a. large portion of
the heat from the airplane engine exhaust. The
air as thus heated continues through a duct 220
and empties into the duct 34, where it passes
across the heat exchanger 22 so as to heat the
ventilating air passing from the ram opening 20
to the cabin 12.
As in the example shown in Fig. 2, the valve A
is connected by means of a crank arm 222, a link
224,‘and a second crank arm 226 to a control valve
228 which regulates the ?ow of hot air from the
duct 220 to the duct 34.
In order to prevent the heat exchanger 2l0
from overheating and burning out when hot air .
of aluminum alloy if desired.
_
From the above description of several embodi
ments of my invention, it will be apparent that
the air conditioning system here shown and de-.
scribed provides ventilation for the air-plane oc
cupants at all times, supercharges the cabin
when such supercharging is desirable, heats the
ventilating air when the airplane is ?ying through
a low temperature environment, and cools the
ventilating air whenever the airplane encounters
hot weather.
While'I have shown and described a preferred
embodiment of my invention, it will‘ be readily
understood by those skilled in the art that varia
tions may be made in the construction disclosed
without departing from the basic features of my
invention. I therefore do not wish to be limited
to the precise construction disclosed, but wish to
include within the scope of my invention all such
modi?cations and variations which will readily
suggest themselves.
Having thus described my invention, what I
claim as new and useful and desire to secure by
Letters Patent of the United States is:
1. In an aircraft air conditioning system for
an aircraft having a cabin, a cabin supercharger,
a ram for supplying air to said supercharger, a
conduit leading from said supercharger to the
cabin, a heat exchanger in said conduit, 8. by~
pass connecting said ram with said conduit to
deliver air to the cabin when the pressure dif
ferential between said ram and said conduit falls
below a predetermined point, a cooling air duct
for supplying air at substantially atmospheric
temperature to said heat exchanger, and means
for supplying a heated gaseous ?uid to said cool
ing air duct.
is not ?owing from the duct 220 to the duct 34,
2. In an aircraft air conditioning system for an
the valve 228 is arranged to divert the hot air
from theduct 220 into a branch duct 230, from 40 aircraft having a cabin, a cabin supercharger,
and a conduit leading from the supercharger to
whence it passes overboard. In other words, the
valve 228, instead of being hinged at itsmiddle
the cabin, the combination of a heat exchanger
so as to act merely as a damper, is hinged at one
in said conduit, a liquid fuel burning heater, an
air ram supplying air under pressure to said
edge in such manner that when it moves up
wardly to close off the connection between the 4.-1 heater, a duct conducting air heated by said
heater to said heat exchanger, means for con
duct 220 and the duct 34, it opens the connection
veying compressed air from said supercharger to
between the duct 220 and the duct 230. Thus
any desired portion of the hot air can be passed
said heater, valve means associated with said last
to the duct 34, the remaining portion passing
overboard through the duct 230.
named means and with said ram, and means re
The system shown in Fig. 3 operates in a man
ner similar to that shown in Fig. 2, but has the
advantage that exhaust gases cannot mix with
said valve means to determine whether said
heater shall receive air from said ram or from
the ventilating air passed to the cabin unless both
of the heat exchangers 2 l0 and 22 become perfo
rated. For instance, a bullet or shell fragment
sponsive to atmospheric pressure for controlling
said supercharger.
3. In a heating system for aircraft, a liquid
fuel burning heater, a ram supplying air for com
bustion to said heater, a heat exchanger deriv
passing through the heat exchanger 2 it) will per
ing heat from the products of combustion of said
mit some exhaust gases to pass into the duct 22!].
These exhaust gases, however, will not mix with
heater, a conduit conveying the products of com
bustion from said heat exchanger to the atmos
the ventilating air unless the heat exchanger 22 is 60 phere, and an adjustable valve in said conduit
for controlling the back pressure on said heater
also perforated. Likewise, perforation of the
whereby said heater will be supplied with su?i
heat exchanger 22 will permit air from the duct
ciently dense air for combustion when the air—
220 to mix with the ventilating air but will have
craft is at high altitudes and thus maintain ef
no disadvantageous effect so long as the heat ex
?cient combustion.
changer 2 l 0 remains sound.
Products of combustion have a corrosive action
upon some metals. It is preferable, therefore,
that the heat exchangers through which burned
gases ?ow be formed of stainless steel or some
other heat and corrosion resistant material. The
heat exchangers referred to are indicated by the
numeral 2| 0 in Fig. 3, and the numeral 22 in Figs.
1 and 2. Inasmuch as hot products of combus
tion do not pass through the heat exchanger 22
_ 4. In an aircraft heating system, the combi
nation of a liquid fuel burning heater, a ram for
supplying combustion air to said heater, 2. super
charger, a conduit leading from said supercharg
er and connected to said ram for conveying air
compressed thereby to said heater, a valve to shut
off said ram, a valve to close said conduit, and
means to cause opening of one of said valves
when the other is closed.
5. In an aircraft heating system, the combina
8,418,110
15
16
tion of a heating apparatus, means including an
air ram for supplying combustion air to said ap
paratus, a supercharger, a conduit for conveying
air compressed by said supercharger to said ap
paratus, a heat exchanger arranged to transfer
heat from the products of combustion of said
the supercharger to said cabin, an after cooler
apparatus to air supplied by said supercharger,
a duct conveying the products of combustion from
said heat exchanger to the atmosphere, a ?rst
valve arranged to shut off the supply of air from
said ram to said apparatus, a second valve ar
ranged to control the ?ow of compressed air
through said conduit, and a third valve arranged
to restrict the flow through said duct, means for
optionally operating'said valves, and means to
in said passageway, a normally ine?ective energy
dissipating cooler connected to said passageway
between said after cooler and the cabin, and
means responsive to an increase in the tempera
ture of said cabin above a predetermined maxi
mum value to render said energy dissipating
cooler e?ective.
12. In an air. conditioning system for an air
10 craft having a cabin and a cabin supercharger,
a passageway for conveying compressed air from
said supercharger to said cabin, a heat exchanger
in said passageway, means to supply heated. air
to said heat exchanger, means to supply cold air
to said heat exchanger, a normally ine?ective
cause at least partial closure of said ?rst valve
energy dissipating cooler in said passageway be
whenever said second valve is opened.
tween said-heat exchanger and said cabin, and
6. The combination set forth in claim 5 in
means to render said energy dissipating cooler
which there is a passageway for conveying air
e?'ective whenever the temperature in said cabin
from said heat exchanger to a space to be heated
rises above a predetermined value.
and in which said passageway is provided with
13. In a heating system for aircraft, a liquid
an optionally operable energy dissipating ex
fuel burning heater, means supplying air for
pander.
combustion to said heater, a heat exchanger de
7. In an aircraft air conditioning system for
riving heat from the products of combustion of
an aircraft having a cabin, a cabin supercharger, 25 said heater, a conduit conveying the products of
and a conduit leading from the supercharger to
combustion from said heat exchanger to the
the cabin, the combination of a heat exchanger
atmosphere, and an adjustable valve in said con
in said conduit, means for supplying a heated
duit for controlling the back pressure on said
-?uid to said heat exchanger, means for supplying
heater in response to atmospheric pressure.
a cooling ?uid to said heat exchanger, control 30
14. In a heating system for aircraft having a
means for respectively rendering said super
- cabin, the combination of a liquid fuel burning
charger and said ?rst or second means effectively
heater, a ram for supplying combustion air to
operative, valve means in said conduit between
said heater, a cabin supercharger, a conduit lead
said heat exchanger and the cabin for regulat
ing from said supercharger for conveying air
ing the rate of ?ow through said conduit, and
compressed thereby to said heater, a valve to
means responsive to the cabin temperature to
shut off said ram, a valve to close said conduit,
move said valve means toward open or closed
and means responsive to atmospheric pressure
position.
.
to open the ?rst said valve and to close the second
8. In an aircraft heating system, the combina
said valve at a predetermined pressure altitude.
tion of a liquid fuel burning heater, a ram for 40
15. In an air conditioning system for an air
supplying combustion air to said heater, a cabin
craft having a cabin, a cabin supercharger, a
supercharger, means for conveying compressed
air from said supercharger to said heater, and
valve means responsive to atmospheric pressure
for determining whether said heater shall be
supplied with combustion air from said super
ram for supplying air to said supercharger, a
conduit leading from said supercharger to said
cabin, means responsive to the atmospheric pres
' sure for controlling the operation of said super
charger, a by-pass connecting said ram with said
charger or from said ram.
conduit to deliver air to the cabin when said
9. In a heating system for an aircraft having
supercharger is not operating, a heat exchanger
a space to be air conditioned and maintained
in said conduit, a cooling air duct for supplying
above a predetermined pressure, the combination 50 air at substantially atmospheric temperature to
of a supercharger, a conduit conveying air under
said heat exchanger, and means for supplying a
pressure from said supercharger to said space, a
heated gaseous fluid to said cooling air duct.
heat exchanger in said conduit, means responsive
16. In air-air conditioning system for an air
to the temperature of the air in said space to
craft having a cabin, a cabin supercharger, a ram
cause effective operation of said supercharger $1 'an for supplying air to said supercharger, a conduit
whenever the said temperature is above or below
leading from said supercharger to the cabin,
a comfort range, means to supply heated air to
means responsive to the cabin temperature for
said heat exchanger whenever the temperature
controlling the operation of said supercharger, a
in said space is below said comfort range, and
by-pass connecting said ram with said conduit
means e?ective to supply atmospheric air to said 60 to deliver air to the cabin when said supercharger
heat exchanger at a temperature lower than that
is not operating, a heat exchanger in' said conduit,
of the air compressed by said supercharger when
a cooling air duct for supplying air at substan
ever the temperature of said space is above said
tially atmospheric temperature to said heat ex
comfort range.
changer, and means for supplying a heated gas
10. The combination set forth in claim 9 in
eous fluid to said cooling air duct.
which there is provided a valve and an energy
17. In an air conditioning system for an air
dissipating cooler bypassing said valve in said
craft having a cabin, a cabin supercharger, a
conduit between said space and said heat ex
ram for supplying air to said supercharger, a
, changer, and means responsive to a temperature
conduit leading from the supercharger to the
cabin, means responsive to atmospheric pressure
said valve to a position substantially restricting
for controlling the operation of said super
flow through said conduit.
charger, means responsive to the cabin tempera
11. In an air conditioning system for an air
ture to control the operation of said supercharger
craft having a cabin and a cabin supercharger,
when the atmospheric pressure is above a pre
a
eway for conveying compressed air from 75 determined pressure, a by-pass connecting said
in said space above said comfort range to move
2,412,11o
I
ram with said conduit to deliver air to the cabin
when said supercharger is not operating, a heat
exchanger in said conduit, a-cooling air duct for
supplying air at substantially atmospheric tem
perature to said heat exchanger, and means for
18
supercharger to said heater, and valve means
associated with said second duct and with said
air ram for determining whether said heater shall
receive air from said air ram or from said super
charger.
'
supplying a heated gaseous ?uid to said cooling
20. In an aircraft air conditioning system for
air duct.
,
an aircraft having a cabin, a cabin supercharger,
18. In a heating system for aircraft, means
and a conduit leading from the supercharger to
for compressing air, a ram in the air stream for
the cabin, the combination of a heat exchanger
receiving air, conduit means for conveying air 10 in said conduit, a liquid fuel burning heater, an
from the ram to the compressing means, duct
air ram supplying air under pressure to said
means for conducting air from the compressing
heater, a duct conducting air heated by said
means to an aircraft compartment, an inter
heater to said heat exchanger, means separate
cooler in the last said duct means, heat exchange
from said cabin for conveying compressed air
means for transferring a portion of the aircraft 15 from said supercharger to said beaten-and valve
engine exhaust heat to an air stream to comprise
means associated with said last named means
a source of hot air, duct means for conducting
and with said air ram for determining whether
hot air from said source to said intercooler, ram
said heater shall receive air from said ram or
and duct means for collecting and conveying cool
from said supercharger.
air to said intercooler, a dump passage connected 26
21. In an aircraft air conditioning system for
to said hot air duct means upstream of said inter
aircraft having a propelling means, a cabin, a
cooler; and valve means for controlling the flow
cabin supercharger, and a conduit leading from
of hot air through said dump‘ passage and for
the supercharger to the cabin, the combination
regulating the ?ow of hot and cool air through
of a heat exchanger in said conduit, a liquid fuel
said intercooler.
25 burning heater separate from said propelling
19. In an aircraft air conditioning system for
means, an air ram supplying air under pressure
an aircraft having a cabin, a'cabin supercharger,
to said heater, a duct conducting air heated by
and a conduit leading from the supercharger to
said heater to said heat exchanger, means for
the cabin, the combination of a heat exchanger
conveying compressed air from said supercharger
in said conduit, a duct for conveying air under 30 to said heater, and valve means associated with
pressure to said heat exchanger, said duct having
said last named means and with said air ram
a part thereof forming an air ram, a liquid fuel
for determining whether said heater shall receive
burning heater located in said duct, a second
said air from said ram or said supercharger.
duct for’ conveying compressed air from said
LYNN A.
, JR.
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