Патент USA US2412110код для вставки
Dec. 3, 1946. 2,412,110 L. A. WILLIAMS, JR AIR CONDITIONING APPARATUS FOR AIRCRAFT Filed Feb. 4, 1943 s Sheets-Shed 1 11.8 //,20 1/25 130 110 fw / 73/ AGE_;_ £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.