US2772828A - Air compressor - Google Patents

Description

Dec. 4, 1956 J BUSH AIR COMPRESSOR Filed 001;. 25, 1952 W-i-TIITI-a:

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United States Patent AIR COMPRESSOR J. Bush, Greensburg, Pa., assignor to Westingho'use Air Brake Company, Wilmerding, Pa., :1 corporation of Pennsylvania This invention relates to air compressors and more particularly to means for controlling the operating temperature andoutput thereof. 1 v

In operation of certain air compressors of the multiple cylinder type, certain of the cylinders may be employed as air exhausting cylinders and certain other cylinders as air compressing cylinders. The air compressing cylinders draw air from the atmosphere and compress same for discharge and use while the air exhausting cylinders withdraw air from :1 containing volume to be exhausted and discharge the withdrawn air to the atmosphere with consequent waste thereof.

In view of the foregoing it 'is one object of the invention to provide means whereby such otherwise wasted discharge of air from the air exhausting cylinders is employed to increase the output of compressed air from the' air compressing cylinders.

- In the operationof air compressors, excessive discharge temperatures, resultant from heat of compression, tend to damage or otherwise cause faulty operation of the discharge valve mechanism either as a direct result of such heat or as an indirect result of carbonized oil de-' posits, in viewof which, it is another object of the in vention to provide a means and method whereby thetemperature of operation of an air compressor maybe reduced from that otherwise obtaining.

"Other objects and advantages will become apparent from the following detailed description of the invention.

Inthe accompanying drawing, the single figure is a schematic view of a multiple cylinder air exhauster compressor device embodying a preferred form of the invention. 7 V

Description Referring to the drawing, the air exhauster-compressor apparatus embodying the invention comprises an air exhauster-compressor device 1, a receiver 2, a pressure, relief valve device 3, and a storage reservoir 4. I

For sake of illustration, the air exhauster-compressor device 1 may comprise three cylinders 5,6 and 7 mounted on a base or casing member 8 common to each. Each 5 of the cylinders 5, 6 and 7 (referring in particular to the cylinder 6 shown in cross-section in the drawing) comprises the usual hollow casing 9 having the usual piston 10 reciprocable therein in sliding sealing engagement with the usual inner cylinder wall 11 forr'nedin the casing. In the well-known manner, the piston 10 serves as a movable abutment defining one end of the usual cylinder chamber 12, the opposite end of which chamber 12.,is closed by a pressure head 13 containing the usual inlet and discharge valves 14 and 15, respectively, which control admission and release of fluid to and from the cylinder chamber 12, respectively; inlet valve 14 being arranged for cooperation with a valve seat 17 to control communication between an inlet port 18 in pressure head 13 and the cylinder chamber 12 via an inlet chamber 16 constantly connected to port 18 and a bore 19 in which a fluted valve stem 19a attached to inlet valve 2 ,7 7 2,828 Patented Dec. 4, 1 956 14 is slidably guided, and exhaust valve 15 being disposed in a discharge chamber 20 and arranged for cooperation with a valve seat 21 to control communication between discharge port 22 and the cylinder chamber 12 by way of the valve chamber 20 and a port 23. A light compression spring 24 disposed in the inlet chamber 16 is arranged to cooperate with the fluted stem 19a to bias the inlet valve 14 toward its seated position, in which it is shown in the drawing, closing ofi the cylinder chamber- 12 from the inlet port 18, and a similar compression spring 25 disposed in the discharge chamber 20 is arranged to-bias the discharge valve 15 toward its seated position, in which it is shown in the dr awing, closin'g off the cylinder chamber 12 from the discharge port 22.1

In the well-known manner, movement of the respective piston 10 in each of the cylinders 5, 6 and 7 through the suction stroke from top dead" center position in proximity of the pressure head 13 to bottom dead center position in which it is shown in the drawing in connection with cylinder 6, will cause a suction in cylinder chamber 12 which urges unseating of inlet valve 14 and admission" of fluid into said chamber 12 via inlet port 18, inlet chamber 16 and bore 19. Subsequent movement of'the piston 10 through-its compression stroke in the opposite direction, i. e. from its bottom dead center position to its topdead center position, will cause compression of the fluid in chamber 12 and displacement of such fluid therefrom via port 23, discharge-chamber 20 and discharge port'22 by unseating of the respective discharge valve 15. a

'Each of the cylinders 5, 6 and 7 comprises the usual connecting rod 26 which operablyf connects, via a pin 27, the respective piston 10 to the usual 'crankishaft" constantly open to 'the atmosphereby wayof' a port through the wall of casing 29.

A'partition 34, serving to. separate the chamber30 from the chamber 32, includes a central opening 35 extending therethrough from chamber to chamber for conveying fluid under pressure therebetween. A tapered valve seat encircling one end' of the central opening 35 in the partition 34 serves to cooperate with a correspondingly tapered valve 36 dis posed in chamber 32 for controlling communication closing;olfi,communication between the receiver 2, con

stantly'connected to chamber 30,; and the atmbsphere to p i which chamber32 is constantly open. The valve 36 will be unseatedby'pressure oflfluid'in chamber30 u pon attainment of a, certain pressure value'sufficient to overi come the, opposing action of spring 37, whereupon coinmunication is established indevice'3 between chambersl 30 and 32 via opening 35 to release fluid under pressure from the receiver 2 to the atmosphere viapipe '31, and in device 3 the chamber 30,. opening 35, the unseated'f valve 3 6, chamber 32 and port 33 to limit the degree of pressure of fluid in the receiver 2, against which the 'exhauster cylinders 5 and 7 must operate, thus assuring that effectiveness of said cylinders Sand 7 as exhausters will not be undesirably influenced by such back pressure 3 in receiver 2. Upon resultant reduction in pressure of fluid in the'receiver 2 to or below'the above mentioned 3 certain pressure value, the action of the spring 37 will seat the valve 36 to close the communication between chambers 30 and 32 via the opening 35 and prevent further release of fluid under pressure from receiver 2 to the atmosphere via device 3 The cylinder 6, for example, may be employed as an an compressing cylinder and as such is provided with a pipe 38 constantly connecting its discharge port 22 to the iiuid' pressure storage reservoir 4, while its inlet port 18 is constantly open to the atmosphere.

The cylinders 5 and 7 maybe employed, for example, to exhaust" fluid under pressurefrom a system via such" as'a'pipe 39- having branches connected ,to'the respective inlet ports 18 in said cylinders 5 and 7, to cause .fluid iromsaid pipe 39 to be drawn into the respective ,cyl inder chambersn via the respective .ports 18, inlet. chambers-16 andbores 19 by-unseating of the respective inlet valves 17 upon repetitive movement of the respective pistons through: their suction strokes from top dead center to bottom dead center of piston travel.

According to a feature of the invention, the respective discharge ports 22 in the cylinder devices 5 and 6 are connected via respective heat exchangers, such as finned pipes 40, to the receiver 2 forstorage of fluid exhausted" from the pipe 39 and subsequent delivery of such fluid 'to the air compressing cylinder 6 to increase output of compressed fluid from'same, rather than discharging such flu d to the atmosphere as is the usual practice. Thefluid under pressure supplied-by the .exhauster cylinders S and 7 to thereceiver 2' is admitted to the compressor cyl nder 6, as through apipe 41 and a port 42 in casing 9 of said cylinder. 6 opening radially into the respective cylinder chamber 12. The port 42 opens into the cylinder wall ll ofcylinder -6in the path of travel of piston 10 and s so located'with respect theretoas to becovered by said: piston substantially during its suction and compression strokes and tobe uncovered'duringfinal movement of;.t he:,p1ston mcompleting its suction stroke and initial movement of the piston inbeginning its compression 7 stroke; covering of the port 42 by piston 10 closing off chamber 12 to the pipe41 while uncovering of said port 42 by movement of piston 10 past same establishes fluid pressure connection between said pipe 41 and said cham berl2,to allow for admission; of .fiuid under pressure from the receiver 2 thereto; It will be understood that;

during operation of-the compressor cylinder 6,.substan-' tially-a full charge of air,;from atmosphere is admitted 'underpressure to the compressor cylinder'6 in'addition to its normal atmospheric charge will increasethe-outputof said cylinder and result in-an-increase in efliciency of oper ation of the exhauste'r compressor device '1.

According to another'impo'rtant feature of the inven-' tron, the" flllld' ounder pressure discharged from the exhauster-cylinders -5 and 7 ispreferably cooled subst'an tially to temperature of the atmosphere by assage" through-such as the finned pipes 40 err-route to'receiver' initial charge in said chamber 12. to avalue substantially equal to that of the fluid in receiver 2, independently of compressive action of piston 10 and consequently at substantially constant temperature. By virtue of such initial pressurization of the compressor cylinder charge, the work required to be performed by the compressor cylinder 6 to raise the initially pressurized charge to the desired discharge pressure is reduced below that which would be required were the initial charge at atmospheric pressure, with the result that the temperature of the compressed fluid discharged from the. cylinder 6 isco'rrespondingly reduced. The cooling effect of the receiver air admitted to the compressor cylinder 6 enables same to be operated at a higher discharge pressure than would be practical otherwise due to the adverseefiect of excessive discharge temperature on operation of a compressor cylinder.

Having now described my invention, What Iclaim as new and desire tosecure by Letters Patent is:

I. In combination with a reservoir for storing compressed air, first, second, and third air compressing means, each of said compressing means includinga cylinder and piston, all said compressing means being of substantially thesame capacity and .all said' pistons being connected to the same prime mover for operation thereby, means connected to'said first and second compressing means for cooling and storing the outputs thereof, said third conipressing means having an inlet and anoutlet, said outlet being connected to the reservoir, and means for admitting cooled air from said cooling andstoring means to said third compressingmeans for addition to the air in said last named compressingmeans admitted through said inlet to increase the output of compressed air from the third compressing means and limit the temperature rise therein resulting from heat of compression to a low value, said first and secondcompressing means supplying air to said co0l-, ingand storing means at avgreater rate than it is delivered from-said coolingand storing means to said third compressing means to thereby insure that a substantial amount of cooledair at asubstantial pressure is always readily available for-introduction into said third compressing meansl,

2. In combination with a reservoir for storing'compressed-air, firstand second air compressing means connected to a prime mover for operation thereby, means additionalto said first .air compressing means for cooling 7 to the cylinder chamber 12 before port 42 is uncovered 2-to remove its heat of compression prior to adrnissionbf; V

such fluid under-pressure to the compressor cylinder'6." The 'fluid under pressure at atmospheric temperature th'us'- admitted intothe compressor-cylinder chamber 12 atthe endiof the inlet stroke of the compressor cylinder piston 10 as-prjeviouslY described, will withthe*charge"of*" during such inle t stroke and increase the pressure of the atmospheric air previousl'yjadmitted to said chamber 12 andstoring the output thereof, conduit means connecting said first'air' compressing means to said cooling and storing means, valve means interposedin said conduit means for preventing air from escaping from the cooling and storing means back into thefirst air compressing means, said'second air compressing means having first and second inlets and an outlet; saidoutlet being connected to the reservoir, and means connected to said cooling and storing means and it! said second ,air compressmg means for V conducting cooled air' from said cooling and storing means to said second air compressing means for admission there to through said first'inlet and for addition to the airm said second air'compr'essing means admitted through said secondinlet'from a'source other than said coohn'g and 'st'ori-ngmeans, the capacity of said first air compressing means being substantially greater thanythe capacity of said second air coinpres'sing means thereby providi'ng that air'is'supplied' to said cooling and'storing means by'said first airj'compressingmeans at a substantially greater rate' tha'n'it'jis' delivered from'said coolingand storing means i .to said seco'n'dair'conip'ressing means and insuring that air remains in sanction ng and storing means a substari tial period of time and becomes effectively cooled, the 'adrnissionof the eftectively cooled air into said second air compressing means serving to limit'to alow value the temperature rise in the'air therein'resulting from heat of 'cgmmession. v

3. Apparatus according to claim 2 including in addition means operatively connected to the cooling and storing 6 means for limiting the pressure of the cooled air therein 1,182,372 Hippie May 9, 1916 to apreselected value. 1,264,562 Rix Apr. 30, 1918 1,445,073 Corpi Feb. 13, 1923 References Cited in the file of this patent 1,467,489 Nordberg Sept. 11, 1923 UNIT 5 1,891,083 Dodge Dec. 13, 1932 866 457 G1,? STATES PATENT: t 17 1907 2,148,638 Patterson Feb. 28, 1939 1 s ep 899,720 Elder Sept. 29, 1908 FOREIGN PATENTS 930,567 Shipley Aug. 10, 1909 314,498 Germany Sept. 25, 1919

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