US2492361A - Compressor control system - Google Patents

Description

Dec. 27, 1949 c. E, HNLEY I COMPRESSOR CONTROL SYSTEM Filed sept. 21, 1945 I N VEN TOR.

rra/aA/yf Patented Dec. 27, 1949 UNITED STATES PATENT" OFFICE COMPRESSOR CONTROLSYSTEM Charles E. Finley, Derry, Pa. Application September 21, 1945, Serial No. .617,813

(Cl. E30-4) 2 Claims.

This invention relates to locomotive carried air compressing apparatus for supplying compressed air to locomotive and train brakes, and more particularly to check valve and compressor unloader valve components for such apparatus.

In the normal operation of locomotive air compressors, after a period of service the outlet valves of the compressor become worn or otherwise defective, so that they leak slightly and permit compressed air from the air storage tank to leak back into the compressor cylinders. As the first stage of the compressor is designed to operate on air at atmospheric pressure and increase the pressure of such air to a value approximately half way between atmospheric and tank pressure, leakage of highly compressed air from the storage tank into the first stage cylinder will develop an air pressure in such cylinder suicient to stall the first stage steam cylinder and thus discontinue operation of the compressor.

When this occurs it is necessary, at present, to remove the compressor from the engine for overhaul even though the leaky outlet valves constitute onlyA a small defect and the compressor is otherwise capable of an extended period of further service before overhaul.

Itis therefore among theobjects of the present invention to provide an improved air compressing apparatus for locomotive and train brakes of such character that the steam operated air compressor may be continued in service on the locomotive fory an extended period after the outlet valves of the compressor start to leak, to install an effective check valve between a locomotive carried air compressor and an associated air storage tank to substantially preclude leakage of air from the storage tank back into the compressor, and to install between the compressor and such check Valve a compressor unloading valve operated by the compressor governor to vent all compressed air from the compressor when operation of the compressor is discontinued by the compressor governor, which check valve andv unloader valve are of simple and durable construction, are easy to install without material modification of the compressor or compressor governor, and are effective to prevent stalling of the compressor before suflicient wear has taken place throughout the compressor to necessitate4 removal of the compressor from the engines for complete overhaul.

Other vobjects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawing wherein:

Figure 1 is a diagrammatic, cross-sectional illustration of locomotive carried air compressing apparatus illustrative of the invention; and

Figure 2 is a transverse cross-section of the check valve component of the apparatus, taken substantially on the line 2--2 of Figure 1.

With continued reference to the drawing, the

apparatus comprises, in general, a conventional steam operated air compressor I0, an air storage tank I I, pneumatically connected with rthe compressor outlet by a pipe line I2, a steam valve'l3 connected at one end to the locomotive boiler and at its opposite end to the steam inlet of the compressor Ill by a pipe line I4, a compressor governor I5 operatively connected with the valve I3 and pneumatically connected by pipe lines I6 and I'I' with the air storage tank Il, a check valve I8 interposed in the pipe line I2 between the compressor outlet and the air storage tank Il, and a compressor unloading valve I9 pneumatically connected by the conduit ZI] to the pipe line I2 between the check valve I8 and the compressor outlet and by a conduit 2| to the compressor governor I5. y

The compressor I0 may be anyone of several known forms of two stage, steam operated air compressors mounted ori railway locomotives to supply compressed air for the locomotive and train brakes. The governor illustrated has a first stage steam cylinder 22 in which a steam piston 23 is reciprocable and a first stage air compressing cylinder 24 in which a first stage air compressing piston 25 is reciprocable. The pistons *23 and 25 are rigidly connected together by a partly tubular piston rod 25 which extends slidably through the top of the air compressor cy1inder 24 and through the bottom of the steam cylinder 22. The adjacent end of the steam pipe I4 is connected to the steam inlet fitting 21 of the compressor and a steam channel 28 leads to the piston operated slide valve 29 and to the steam operated piston valve 30 which controls the application of steam at boiler pressure to the opposite sides of the steam piston 23.

The first stage air compressing cylinder 24 is equipped with two air intake strainers 3l disposed atrespectively `opposite ends of the cylinder and two similarly disposed air intake valves 32 for admitting air at atmospheric pressure kinto the first stage cylinder. As the rst stage air compressing piston 25 works upon `air admitted at atmospheric pressure and as the rst stage steam piston 23 is acted upon by steam at boiler pressure, the piston`25 is much larger than the piston 23 in order to initially compress a large ,compressing cylinder 42,.

volume of air by an economical quantity of steam. Under these conditions, if air should leak from the storage tank l l through the compressor outlet valves back into the rst stage cylinder 24 and build up a pressure in this cylinder slightly above the delivery pressure of the nrst stage cylinder of the compressor, the steam piston 23 would have insuicient area to move the air compressing piston 25 and the compressor would stall since the valve 29, could not,A then be operated. The slide valve 29 is connected to the piston rod 26 by a valve rod 33 having a headed end received in the bore of the partly tubular piston rod vso that the slide valve is moved froml one to, the other of its two operated positions as the pistons 23 and 25 approach the opposite ends` of their stroke. The slide valve 2 9, controls thev application of high pressure steam to the opposite ends of the piston valve 30 so that the pistonvalve i-s operated to apply steam at boiler pressure from tho-steam inlet 21 to-onposite Sides), of the piston 23 in proper timed relationship to the reciprocal movements of the piston incylinder 2.2 and to apply the. exhaust from. cylinder- 22- to the-second Stage Steam operated piston- 34.- reoiprfoooble in second stage cylinder- 35,- in` timed relationship to the reciprocatingmQ-Vements of piston. 34, and to exhaust; steam fror'n-V second stage cylinyder: 35 through the exhaust stoom channel 36 and exhaust outlet fitting 31. Second stage, Steam- Cylinder s4; is, connected bva piston rod 3.8.15@ a, second stage air compro-saine piston 39 which is reciplooable in the second stage air the: piston 39 works. against. lore-compiles,sed-` air from cyli-n.- der. 2-4 and the piston- 314- is, acted upon; by low pressure steamexhausted fromv the first stage steam cylinder 22 pistoni 3d;y is materially larger than piston 3-9. in order to highly compress the air; by the exhaust steam. from the first stagef steam cylinder.

The rst Staes compressing.- ovlirider 2.5 is provided with outlet valves 4|; which.k control: the passage of air from the first stage, compressing -oylindor into the Scoor-1dstagecompressing ovlmiler and. preventianyreturnof airfrom the second. stage to. the staseoylirider-acd the, seoorid stage. Cylinder 4i).- is provided; with air outlet valves 4,2- whichcontrol the passage: or air from the second stage; compressing cylinder- 40 to, the air outlet fitting 43 and througl-ii the. pipe line t2 tothe storage tank Ll and prevent rotor-,11i of air from the storage tank: 1111110.- he-seco-nd stageconrpressing cylinder of, the compressor. It is.` these outlet valves. 4 l,- and 42, which, when slightly worn, corroded, dirty or otherwise r defectivepemni th leakage .ot air from the storage tank e book?.v into the compressing cylinders: of the`V oir. compressor.

As the compressor if() is of. conventional1 and well known construction.: a further description thereof is. not considered to; be necessary for the purposesoi the present. diodosuro;y

The. steam valineI lit which controls; the supply of steam to. the steam, operated portion of; the air con'ipressorv comprises. a, hollow body 4-3- provided withan.. apertured. partition Mi, with an outlet fitting, 45 connected to. theY adjacent end of-A the pipe line |.-l. and with. anoutlet tting 46 connected by a. suitablepipe line. not illustrated, to

.thesteam dome of the locomotive boiler. A valve head 41. plunger '38,A the upper end or which. is securedto .ar piston 4S, reciprocable in a valveL cylinder 50,

issecured on2 the lower end of astem or the upper open end of which movable cylinder head l,

isclosed by a rewhich is centrally apertured and provided with a tubular stud 52 screw threaded into such aperture. The piston and valve head are urged to the position illustrated in Figure l, in which the valve head is displaced from the partition M to open the valve, by a compression spring 53 and the piston is moved to bring the valve head into engagement with the partition 44 and close the aperture through the partition by the pressure of compressed air in the chamber 54'. between the piston and the cylinder head 511.

The governor l5 comprises two identical air pressure responsive units 55 and 55 pneumatically connected with chamber 54. The two units 55 and 55 are provided in order to provide brake a-ir at-twodiilerent pressures for diierent operating conditions of the locomotive. For example, the unit 55 may be a low pressure governor and set for an air pressure of one-hundred pounds per square inch, while the unit 55 may be a high pressure unit and set for an airpressure of onehundred and thirty pounds per square inch. The two units; are usedalternatively depending upon thev operating conditions under which the locomotive is beingused andt such: two unit governor-s are usually provided only onl freight locomotives which are used for longhauls witht heavy and light trains and are also used for shifting and other operations. The selection of the units and 55' is determined-,by operationofv the-manually controlled valves 551 and 5,1s provided inthe conduits [6 and l1 between4 the-respective. units andl the. storage tanlr |-,I. As the-twounits 55 and 55 are-substantially identical. in construction and operation, a detailed illustrationx andt description oionly one is considered suiiicientf for the purpose of the present disclosure.

The unit 55. selected for detailed, illustration, has a base 1.56 provided in. its upper end with fa chamber |51. An air inlet. fitting 58- at one side-ofA the base receives the adjacent end ot the conduit l1. and communicates. with the chamber L5J1.. At its. lower endtheV baseA isA provided with a reduced, screw-threaded. extension 59- received in, a fitting (il)l of the hollow bracket 6J.. The hollow bracket includes a chamber 62 which communicates through thetubular stud- 52 with theV chamber 54: inthe Valvepiston head: 5L and the base. is provided with abore- 63 which. extends fromv the chamber 15,1 to the char-riber- & 2- and is restricted: at its. upper end-f. A needle valve plunger 6.4- isv carried in the. cham-bert5]- by a nexible diaphrarn 65 inj position to close the upper end of, bore 63` `and a compression spring 65 mounted., a spring cylinder 61 bears upon` the upper side of the flexible diaphram1 to resiliently maintain the valve plunger or needle 6# ink closing' relationship with theupper endot the. bore 63'.l A spring abutment 68 is, threaded; intoz the upper end ot the cylinder 61,- and is. adjustable the cylinder to` vary the loading on; the spring 6.6 and; thereby change the air pressure: aty which th@ governor unitA is operative to close the valve |.3 A- removable cap- 69- is secured; tothe upper endvv of cylinder 6-1v covering. the'alzautgment 53'.

In operation, whenthe pressure ofthe air` in tank II- reaches a predeterminedV value and assuming that the-valve 51 is open, thisar pressure acts onthe-u-nders-ide ofnlexible diaphram 65 and raises v alve plunger 641 ofi' of its seat at. the upper end of .bore 63 so that air passes from the chamber l-51 through the bore; 63,-' into the chamber 62 and `from the chamber 62; throughthe hollow stud 52- into the` chamber 5,4 to force the piston 49 downwardly and close the steam valve.

This cuts off the supply of Asteam to the steam operated portion of the air compressor and discontinues operation of the compressor. As soon as the pressure in storage tank II falls below the predetermined pressure the spring 86 expands ca'using the valve plunger or needle 54 to close the upper end of bore 63 and cut off the Supply of compressed airV to the chamber 54. The base 56 is provided with a bleed opening 10 through which the air trapped below the valve plunger` 84 escapes permitting the piston 49 to rise in its cylinder and the valve I3 to open under the influence of the compression spring 53 to again place the air compressor in operation.

A conduit 1I is frequently connected to one end of the hollow bracket 6I and extended into the cab where it is provided with a manually controlled valve 12 so that the engineer can discontinue operation of the governor and maintain the compressor in operation under emergency conditions, the storage tank II being provided, of course, with a suitable safety or blow-ofi valve, not illustrated.

The check valve I8 ycomprises a hollow, elongated cylinder 13 having at one end a domeshaped end wall 14 provided with a central aperture 15 and having internal screw threads 18 near its opposite, open end. Intermediate its length the .cylinder is provided with a transverse partition 11 having a central aperture 18 and a plurality of apertures 19 surrounding the central aperture.

A check valve stem 80 is slidable in the central aperture 18 V'of the partition and carries a valve disc 8l which seats on theside of the partition 11 adjacent thestorage tank II to close the apertures 19, and thus prevent return flow oi air fromV the tank to the compressor. The valve disc 8! is preferably a composite structure including a disc.,82 of suitable resilient material, such fas 'synthetic rubber, and a metal washer 83 overlying th`e major portion of the surface oi the disc 82 opposite the partition 11.

An externally screw-threaded plug 84 is threaded into the open end of the cylinder 13 and provided with a screw-threaded centra! aperture which receives the adjacent end of the portion 85 of the pipe line I2 extending from the check valve to storage tank II. This plug is provided at its inner side with a hollow, tapered boss 88 having its distal ends substantially parallel to the partition 11 and having a plurality of openings 81 in its wall.

The portion 88 of the pipe line I2 between the compressor outlet and the check valve has its end remote from the compressor received in the aperture 15 of the end wall of the cylinder 13. This end of the pipe line portion 88 is reduced at the location of the aperture and ared within the cylinder to direct jets of air from the compressor through the apertures 19 against the valve disc 8| to raise this valve disc and permit free flow of air through the check valve from the pipe line portion 88 to the pipe line portion 85. The boss 86 stops the upward movement of the valve disc and the air flows from the apertures 19 around the disc and through the openings 81 in the wall of boss 86 and into the portion 85 of the pipe line I2. When the compressor is not operating the disc 8I rests upon the partition 11 and closes the apertures 18 and 19 so that air cannot return through the check valve.

The construction of the check valve I8 is such that this valve will operate for an extended period of time, usually much longer than the period .ture 99 so that when forced toward the end plug 93, the valve cylin- Vduring which'the outlet valves compressor are entirely leak proof. And even in chamber sz of the hollow bracket el this air is applied through 4I and 42 of the the event of leakage of the valve I8, this valve can be removed and replaced by a new valve lvery quickly and easily and such replacement of -the check valve will permit continued use of the compressor even though the compressor outlet valves are subject to some leakage.

The compressor unloading valve I9 comprises ."an elongatedcylinder 9i) having at one end a .centrally Iapertured end :ternal screw-threads 92 ,An apertured plug 93 is threaded into the open fend of the cylinder and a valve plunger 94 'comprising 96'connected by a rod or reduced portion 91 is reciprocable in the cylinder 9U. .spring 98 is disposed in Yvalve piston 99 and end 'urge the valve plunger toward the end wall 9|. :The conduit 29 is connected at one end to the j'portion 88 of the pipe line I2 between the comwall 9| and having inat its opposite, open end.

two spaced-apart valve pistons and A compression the cylinder between the plug 9,3 to resiliently pressor outlet and the check valve I8 and is connected at its opposite end to the unloading valve I9 through an aperture 99 in the wall of Icylinder 90 intermediate the length of the cylinder. to the end ywall 9| by The conduit ZI is connected at one end a i'ltting |00 extending into the end rwall aperture and is connected at its Aopposite end to the hollow bracket 8l in com- `munication, with the chamber When compressed air is admitted into the through the base, the pressure of the conduit 2I against the unloading valve, forc- 94 toward the end plug 93 bore v83 of the governor the valvevpiston 95 of ing the valve plunger -againstthe force of spring 98. The cylinder 98 is provided in its wall with a vent opening I0! disposed between the end plug 93 and the aperthe valve plunger 94 is der connected end of conduit 20 is in communication with the vent aperture IUI to vent any compressed air from the compressor when operation of the compressor is stopped by closing of the steam valve I3.

This unloading of the compressor maintains the pressure in the air compressing cylinders of the compressor substantially at atmospheric pressure so that the steam pistons .can easily move the air compressing pistons as soon as the steam valve I3 is open and the compressor will not stall.

The invention may be embodied in other specii'lc forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

Having thus described my invention, what I claim as new land desire to secure by Letters Patent is:

1. In locomotive carried air compressing apparatus, a steam operated air compressor, an air storage tank pneumatically connected to the outlet of said compressor, a steam valve controlling the operation of said compressor, and an air operated governor operatively connected to said valve and pneumatically connected to said airstorage tank to. close saidv steam valve when the air pressure in said tank reaches a predetermined value, a check Valve disposed in the pneumatic connection between said storage tank and said compressor and arranged to prevent ow of air from said tank to said compressor while permitting free ow of air from. said compressorVV to said tank, and a compressed air operated unloading valve pneumatically connected to said compressor outlet and to said air operated governor and operated by said governor uponV steam valve closing operation of the governor to vent compressed air from said air compressor, said check valve comprising an elongated hollow cylinder having an open end and an apertured end wall at its other end and an apertured transverse partition therein intermediate its length, an apertured plug secured in the open end of said' cylinder and having a hollow boss extending into said cylinder and spaced from said partition, said boss having openings in its wall, and a valve disc disposed between said partition and said boss and operative to close the apertures in said partition, said end wall receiving one end of the compressor connected portion of the pneumatic connection between said compressor and said storage tank and said plug receiving one end of the. tank connected portion of such pneumatic connection.

2. In locomotive carried air compressing apparatus, a steam operated air compressor, an air storage tank pneumatically connected to the outlet of said compressor, a steam valve controlling the operation of said compressor, and

an air operated governor operatively connected to said valve and pneumatically connected to said air storage tank to close said steam valve when the air pressure in said tank reaches a predetermined value, a check valve disposed in the pneumatic connection between said storage tank and said compressor and arranged to prevent ow of' air from said tank to said compresser while permitting, free flow of air from said compressor. to; said tank, and a compressed air operated unloading valve pneumatically connected to said compressor outlet and to said air operated governor and operated by said governor upon steam valve closing operation of the governor to, vent compressed air from said air compressor, said unloading valve comprising an elongated hollow cylinder having an open end and an apertured end Wall at its other end, a conduit receiving aperture intermediate its length and a vent opening between said conduit receiving aperture and its open end, an apertured plug secured in the open end of said cylinder, a valve plunger sl'idabl'e in said cylinder and having two spacedeapart valve pistons, and a compression spring between said valve plunger and said end plug, said unloading valve being pneumatically connected at said conduit receiving aperture with the outlet of said compressor at said end wall aperturel with said compressor gavernorf,V and said valve plunger being movable by compressed air from said governor toconnect said cond-uit receiving aperture with said vent opening.

CHARLES E'.

REFEREINTCESl CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 674,808 Christensen May 21, 1901 689,565 PreIlWitZ. Dec. 24, 1901 1,416,092 Knaak May 16, 1922 1,695,368. Conrad'er Dec. 18, 1928 1,817,698 McMillan Aug. 4, 1931 2,043,058; Ploeger June 2, 1936 2,083,740 Paullin l June 15, 1937 2,124,390- Anderson July 19, 1938 2,213,743 Miner- Sept. 3. 1940

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