US2216690A - Air conditioning apparatus and method - Google Patents

Description

Oct. 1, 1940. J MADDEN 2,216,690

AIR CONDITIONING APPARATUS AND METHOD Filed Dec. 7, 1936 4 Sheets-Sheet l wnmsssa; i INVENTOR: a WLZZmm JMaddzn,

Oct. 1, 1940. w J MADDEN I 2,216,690

AIR CONDITIONING APPARATUS AND METHOD Filed Dec. 7, 1936 4 Sheets-Sheet 2 W1 TNESSES IN V EN TOR:

W William lflfaddm A5 Y I B TTORNEYS.

Oct. 1,1940. w J, MADDEN 2,216,690

AIR CONDITIONING APPARATUS AND METHOD Filed Dec. 7, 1936 4.Sheets-Sheet 3 AIR FLOW lllllllllllllllflllIIlIllll All? FLOW W] TNESSES I N V EN TOR TTORNEYS.

Oct. 1, 1940. w. J. MADDEN 2,216,690

AIR CONDITIONING APPARATUS AND METHOD Filed Dec. 7, 1936 4 Sheets-Sheet 4 zgggqyt 23b 2 H/R FLOW R FLOW INVENTOR;

William J." Madden WITNESSES:

Patented a. 1, 1940 PATENT OFFICE AIR CONDITIONING APPARATUS AND METH William J. Madden, Lansdowne,.Pa., assignor to The Pennsylvania Railroad Company, Philadelphia, Pa., a corporation of Pennsylvania Application December 7, 1936, Serial No. 114,569

11 Claims.

This invention relates to apparatus and methods in which a compressib'r. circulating refrigerantis utilized in a closed circulatory system to condition the air within a railway car or other 6 enclosure intended for human occupancy; and

it has reference more particularly to mechanical air conditioning apparatus and methods for railway passenger cars.

With the usual forms of mechanical conditioning apparatus for railway cars, a certain amount of fresh air is admitted into the car at all times, and the compressor stopped and started automatically under control of thermostatic means. During the ofi cycles of such apparatus, considerable moisture is carried into the car with the fresh air and to this is added the moisture emanating from the passengers. The excess moisture thusaccumulated renders diflicult the maintenance of a properly conditioned atmosphere within the car. Moreover, with the off and "on types of control, the dry bulb temperature drifts since a considerable interval elapses between the time that the thermostat functions and the time that the thermal change is effective within the car, with attendant causation of alternate warm and cool air currents. The frequent starting and stopping of the compressor is moreover disadvantageous because of the excessive wear incurred and be- 39 cause of the high upkeep cost of the electric instrumentalities which are essential to the control of the compressor.

My invention is directed toward overcoming the above mentioned drawbacks of previous 35 practice, that is to say, I aim to make possible the maintenance within a passenger car or other enclosure intended for human'occupancy at all times, of a, properly conditioned atmosphere as regards both temperature and humidity which 40 is consistent with external atmospheric changes. This objective I realize, as hereinafter more fully set forth, through provision of. a simple and efficient method and economically operative automatic apparatus wherein the compressor is 45 continuously run and its functioning controlled to vary the rate of circulation of the refrigerant by modulation dependent upon variations in the differential between the temperature of fresh air constantly admitted into the car and the so temperature of the atmosphere within the car,

which atmosphere is maintained in constant circulation by suitable means embodied in the apparatus.

Other objects and attendant advantages will 55 appear from the following detailed description apparatus.

of the attached drawings, wherein Fig. I is diagrammatic view of a mechanical air conditioning apparatus conveniently embodying my invention in one form, and suitable to the practice of my new method.

Fig. 11 is a vertical sectional view through an evaporator forming one of the elements of the Fig. III is a view of the evaporator looking as indicated by the arrows III-III in Fig. II, 10 with the end wall nearest the observer removed.

-Fig. IV is a view corresponding to Fig. I showing an alternative form of my improved air conditioning apparatus; and v Fig. v is likewise a view similar to Fig. 1 show- 15 ing another alternative form of apparatus. Referring first to Fig. I of these illustrations,

the air conditioning apparatus there diagrammatically shown includes a high-speed compres- 'sor 5 which delivers through a pipe 6 to a condenser l. Interposed in a pipe 8 leading from the condenser l to an evaporator 9, is .a liquid receiver l0 and an expansion valve II of a suitable commercial type. By means of a return pipe. line I 2, the vaporized refrigerant is conducted from the evaporator 9 to the compressor 5. A motor driven fan I3 is employed to circulate outside over the condenser l. Another motor driven fan l4 constantly circulates the air within the enclosure or car over the evaporator 9. It is to be understood, of course, that in actual practice the elements thus far described are all suitably allocated for cooperation in a well-known manner.

For the purpose of automatically controlling the refrigerating system of'the apparatus to maintain a properly conditioned atmosphere within the enclosure or car, I have made provisions which, in this instance, include a continuously operating electric driving motor l5 for 0 the compressor 5-, said motor having a shunt field winding [6 and receiving current through conductors I1 and I8 from a suitable source of supply, not illustrated. Connected in series with the shunt field winding [6 of the motor I5 is a 5 carbon pile l9 which is subject to the pressure of a lever 20 fulcrumed at 2|, and actuated, through a rod 22 by a'diiferential thermostat comprehensively designated 25. As conventionally shown, the thermostat 25 comprises a pair of sylphon'bellows 26 and 21 which react oppositely upon a member 28 to which the rod 22 is connected, the bellows 26 being in communication, by way of a tube 29, with a bulb 30 in the path of fresh air admitted into the enclosure or car from the outside through a suitable opening (not shown) and containing a thermally sensitive volatile fluid. The bellows 21, on the other hand, is in communication, by Way of a tube 3|, with a bulb 32 positioned in the path of the air emanating from the evaporator within the enclosure or car and containing a similar thermally-sensitive volatile fluid. By virtue of this arrangement, it will be apparent that with modulation between the temperature of the incoming fresh air and the temperature of the air circulated within the car, the thermostat 25 will cause the lever 20 to be moved downwardly or upwardly to increase or decrease thepressure on the carbon pile 19. As a consequence, the resistance in the field circuit of the motor [5 will be correspondingly increased or decreased to vary the speed of the motor I5 and in turn that of the compressor 5, with attendant variation in the amount of the refrigerant circulated through the refrigerating system. In this way, it will be seen that I am able to maintain a conditioned atmosphere within the car, the temperature and moisture characteristics of which are predeterminable by proper proportioning of the parts embodied in the thermostatically-actuated means whereby the modulated control is effected.

In the event of excessive discharge pressures or low suction pressures, the apparatus is protected against injury through automatic actuation of a three way valve 33 in the pressure line 6 which leads from the compressor 5 to the condenser 1, so that the refrigerant is shunted through a cross pipe 34 connecting into an equalizing chamber 35 interposed in the suction line I 2. The operating lever of the valve 33, it will be noted, is coordinated with a suitable high-low pressure device conventionallyrepresented at 36 which is in communication with the pressure and suction lines 6 and I 2 by way of pipes 37 and 38. A check valve 39 automatically shuts off the suction line I 2 when the valve 33 is operated by the device 36 so that the flow of the refrigerant from the compressor is diverted directly into the equalizing chamber 35.

In order that the maximum efiiciency may be attained in a mechanical refrigerating system controlled under the above principle, I employ an evaporator 9 of the construction diagrammatically illustrated in Figs. II and III. In the evaporator 9, the coils 40 are composed of units 4| arranged one above the other with continuous parallel fins. or moisture collecting plates 42 mounted on these tubes. As shown, the opposite ends of the coil units 4| are connected to horizontal headers or manifolds 43, 44 which are in turn intercommunicative by Way of vertical manifolds 45, 46, the pressure and suction line 8 and I2 being respectively connected to said vertical manifolds at the levels indicated. During operation of the apparatus with the compressor 5 running at slow speed the correspondingly small amount of refrigerating medium being circulated will pass, say through the lowermost section 4| of the coils 40 only instead'of through the whole of said coils as would be the case with evaporators as ordinarily constructed. By thus segregating the flow of the refrigerating medium, an effective thermal exchange is assured between said medium and the air passing through the evaporator notwithstanding the reduced flow. With increased circulation of the refrigerating medium as the compressor is speeded up, the additional fiow will be accommodated successively by the horizontal coll units at the higher levels of the evaporator until the maximum load is reached when all the coils will be traversed.

In the alternative embodiment of my invention illustrated diagrammatically in Fig. IV, the compressor 5disconstantly operated, through a variable speed drive 41, from the shaft 48 of a speed reducing unit 49 which is coordinated with a motor (generator) |5a in turn driven by a Spicer or similar drive from one of the wheel axles 5| of the car. As shown, this drive includes a speed multiplying unit 52 on the car axle 5i, and a propeller shaft 53 which is coordinated, through an automatic clutch 55 with the shaft 56 of the motor (generator) I5a. At 51 is conventionally indicated the exciter for the motor (generator) l5a. The variable speed drive 41 is shown as being of the type wherein a bevel edged belt 58 connects a pair of laterally adjustable pulleys 59, 60 one of which is in this instance mounted on the compressor shaft, and the other on the shaft 48 of the speed reducer 49, said pulleys comprising opposing cone components 6!, 62 and 63, 64 respectively. The cone component 6| of the pulley 59 is fixed on the compressor shaft, while the opposing component 62 is slidable axially on said shaft and yieldingly urged away from the component 6| by an interposed coiled compression spring 65 surrounding the shaft. Similarly, the cone component 83 of the pulley 60 is fixed to the speed reducer shaft 48 and the opposing component 64 is axially shiftable on said shaft but yieldingly urged toward the component 63 by a spring 66. Here, as in the first described embodiment of my invention, the capacity of the compressor 5a is automatically varied for maintenance of a properly conditioned atmosphere within the car under the control of a differential thermostat 25a. which, through a fluid pressure system comprehensively designated 61, governs the variable speed drive 41. In the system 61, the pressure fluid is continuously circulated by a motor driven pump 68 through a closed circuit defined by piping 69 in which is interposed a reservoir '10, a sylphon bellows 'llwhereof the movable end bears against the shiftable component 62 of the pulleys 59, and a by-pass valve 12 which is directly actuated by the differential thermostat 25a. The building up of abnormally excessive pressures within the system 61 is prevented by diversion of a portion of the fluid flow through a cross pipe 13 in which a relief valve 74 is connected. At all train speeds above the cut-in speed of the automatic clutch, the compressor 511 will be driven directly from the wheel axle 5| while at station stops or slow train speeds, it will be driven by the compressor motor which at these times will receive current from a battery indicated at 15, under control of an automatic switch 16. Thus the motor (generator) operates as a motor to drive the compressor 5 during station stops and as a generator to charge the battery 15 while the car is in motion. In order to preclude the necessity for repetitive description, those elements not specifically referred to in Fig. IV but having their counterparts in the first described embodiment, are identified with the same reference numerals previously employed, with addition however in each in stance, of the letter a for the purposes of distinction.

Obviously with the alternative arrangement of Fig. IV, the actuation of the by-pass valve '12 by the differential thermostat 25-1 will result i::

increase or decrease of the fluid pressure within the system 61, so that through cooperation of speed of the compressor. The described arrangement is moreover capable of compensating for 1 the different speeds at which the motor (generator) is driven from the car axle. In the alternative form of my invention illustrated in Fig. V, the compressor 51? is driven at substantially constant speed by an electric motor I51), and the refrigerating capacity varied to suit the demands for cooling by progressively unloading the cylinders of said compressor and vice versa. For convenience, I have shown a compressor 5b with four cylinders designated l-4, having their discharge outlets connected to the pressure line 8b by branch pipes 18-8! respectively, and their inlets connected with the suction line lZb by branch pipes 82-85. Interposed in the branch pipes 'I8-8l are three way valves 86-89 which are adapted to be operated against spring action by solenoids 9I-94, and which are connected by branch pipes 95-98, with the suction line lZb. As shown, the corresponding terminals of the solonoids 91-94 are individually connected to contacts ll-I04 by conductors IDS-I88, while their other terminals are connected in common by a conductor I89 with a switch plate H8 at the end of the thermostatically actuated arm 20b, adapted to overtravel said contacts. The current for energizing the solenoids 9l-94 is supplied by a battery HI interposed in the conductor I89 together with a switch H2, which latter is arranged to be opened automatically by the high low pressure device 36b for unloading all the compressor cylinders for protection of the apparatus in case of excessive discharge pressures or low suction pressures. Here again, those elements in Fig. V which have not been separately referred to but which have their counterparts in the first described embodiment, are identified by the same reference numeral previously employed, but distinguished in each instance by addition of the letter b. With the arm 28b in the position shown, only the cylinder 4 of the compressor 5b is effective in maintaining circulation of the refrigerant through the cooling system, the valves 86-88 being set so that the other cylinders l3 are unloaded and discharging into the by-pass pipes 95-91. As the requirements for cooling increase, the arm 20b is moved downwardly under the action of the differential thermostat 25b, and the other compressor cylinders progressively loaded in the order 2-3-l by successive actuation of the valves 88, 81, 86. On the other hand, as the desired atmospheric condition isapproached in the car, thecylinders of the compressor 5b will be progressively unloaded in the order l3-2-4 through reverse actuation of arm 2811 by the differential thermostat.

'The different cooperating elements particularly shown and described for convenience of illustration in connection with the organizations of Figs. I, IV and V are of course to be regarded as typical of others which may be substituted to perform analogous functions in my new method of air conditioning, without departing from the scope of my invention as defined in the appended claims. I

Having thus described my invention, I clair'nz 1. The method of conditioning air in a railway car or other enclosure intended for human occupancy, with apparatus utilizing a multi-cylinder compressor to circulate a compressible refrigerant in a closed circulatory system, which comprises continuously operating the compressor,

constantly admitting fresh air into the car, constantly circulating the atmosphere within the car, and governing the compressor by progressively loading and unloading its cylinders to vary the rate of circulation of the refrigerant in the system by modulation dependent upon variations in the difierential between the temperature of the incoming fresh air and the temperature internally of the car.

2. In air conditioning apparatus utilizing a compressible refrigerant, a closed circulatory system 'with an interposed continuously-operating compressor; a condenser and an evaporator having vertically-manifolded horizontal sections in superposed relation; and means including a dif-,

ferential thermostat responsive to temperature changes externally and internally of an enclosure being conditioned, for automatically controlling the capacity of the compressor and, in turn, the rate of circulation of the refrigeant in the system.

3. In air conditioning apparatus for a railway car or other enclosure intended for human occupancy, utilizing a compressible refrigerant, a closed circulatory system with an interposed continuously-operating compressor; means for constantly admitting fresh air into the car; means for constantly circulating the atmosphere within the car; an electric driving motor for the compressor; a variable resistance means in circuit with the field winding of the motor; and means including a differential thermostat responsive to temperature changes in the incoming fresh air and the air internally of the car, for actuating the variable resistance to correspondingly vary the speed of the compressor motor and thereby control the rate of circulation of the refrigerant in the system. i

4. In air conditioning apparatus for passenger cars utilizing a compressible refrigerant, a closed circulatory system with a continuously-running compressor interposed therein; a motor (generator) normally operated, through an automatic clutch, from one of the wheel axles of the car while the car is in motion; a battery charged at train speeds above the cut-in speed of the automatic clutch and .adapted to furnish energy for the operation of the compressor at low train speeds and during station stops; a variable means coordinating the motor (generator) and the compressor; and means including a differential thermostat responsive to temperature changes externally and internally of the car for actuating the variable speed means to govern the speed of the compressor, and in turn, the rate of circulation of the refrigerant in the system.

5. In air conditioning apparatus for a railway car or other enclosure intended for human occupancy, utilizing a compressible refrigerant, a closed circulatory system with a continuously running multiple-cylinder compressor interposed therein; by-passes around the cylinders of the compressor; individual flow control valves in said by-passes; means for driving the compressor; means for constantly admitting fresh air into the car means for constantly circulating the atmosphere within the car; and. means including a differential thermostat responsive to temperature changes in the incoming fresh air and in the air internally of the car, for automatically actuating the by-pass valves to progressively load and unload the compressor cylinders, thereby to control the rate of circulation of the refrigerant in the system.

6. In air conditioning apparatus for a railway car or other enclosure intended for human occupancy, utilizing a compressible refrigerant, a closed circulatory system with a continuously running multiple-cylinder compressor interposed therein; by-passes around the cylinders of the compressor; individual magnetically-operated flow control valves in said by-passes; means for driving the compressor; an electric circuit including individual switch contacts for the valve magnets and a switch plate movable over the contacts; means for constantly admitting fresh air into the car; means for constantly circulating the atmosphere within the car; and means including a dififerential thermostat responsive to temperature changes in the incoming fresh air and in the air internally of the car, for moving the switch plate to effect successive actuation of the by-pass valves and progressive loading and unloading of the compressor cylinders to control the rate of circulation of the refrigerant in the system.

7. The method of conditioning air in a railway car with apparatus utilizing a compressor to circulate a compressible refrigerant in a closed circulatory system, main power means operated from one of the wheel axles of the car while the car is in motion, axiliary power means operative during station stops, and variable speed means connecting the main and the auxiliary power means with the compressor, which method comprises constantly admitting fresh air into the car; constantly circulating the atmosphere within the car; and controlling the variable speed means through modulation dependent upon variations in the difierential between the temperature of the incoming air and the temperature within the car.

8. The method of conditioning air in a railway car with apparatus utilizing a compressor to circulate a compressible refrigerant in a closed circulatory system, a motor (generator), an automatic clutch through which the motor generator is operated from one of the wheel axles of the car while the car is in motion, a battery charged at train speeds above the cut-in speed of the automatic clutch and adapted to furnish energy for operation of the compressor at slow train speeds and during station stops, and variable speed means interposed between the motor generator and the compressor, which method comprises constantly admitting fresh air into the car; constantly circulating the atmosphere within the car; and controlling the variable speed means by modulation dependent upon variations in the difierential between the temperature of the incoming air and the temperature within the car.

9. In air conditioning apparatus for passenger cars utilizing a compressible refrigerant, a closed circulating system with a continuously running compressor interposed therein; main power means operated from one of the wheel axles of the car while the car is in motion; auxiliary power means operative during station stops; variable speed means connecting the main and the auxiliary power means with the compressor; and means responsive to temperature changes within the car for controlling the variable speed means to govern the speed of the compressor, and in turn, the rate of circulation of the refrigerant in the system.

10. In air conditioning apparatus for passenger cars utilizing a'compressible refrigerant, a closed circulating system with a continuously running compressor interposed therein; main power means operated from one of the wheel axles of the car while the car is in motion; auxiliary power means operative during station stops; variable speed means connecting the main and auxiliary power means with the compressor; and differential thermostat means responsive to temperature changes exteriorly and interiorly of the car for controlling the variable speed means to govern the speed of the compressor, and, in turn, the rate of circulation of the refrigerant in the system.

1. In airconditioning apparatus for passenger cars utilizing a compressible refrigerant, a closed circulatory system with a continuouslyrunning compressor interposed therein; a motor (generator) normally operated, through an automatic clutch, from one of the wheel axles of the car while the car is in motion; a battery charged at train speeds above the cut-in speed of the automatic clutch and adapted to furnish energy for the operation of the compressor at low train speeds and during station stops; variable speed means coordinating the motor (generator) and the compressor; and means responsive to temperature changes within the car for controlling the variable speed means to govern the speed of the compressor, and in turn, the rate of circulation of the refrigerant in the system.

WILLIAM J. MADDEN.

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