US13348A - Improvement in alr-endlnes - Google Patents

Description

J. ERIGSSON.

AIR ENGINE.

PATENTED JULY 31, 1855.

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UNITED STATES PATENT QFFICF.

JOHN ERIOSSON, OF .NE YORK, N. Y.

IMPROVEMENT lN. AIR-ENGINES.

Specification forming part of Lettcrs Patent No. 13,348, dated July 31, 1955.

To an whom it may concern.-

' Be it known that I, John ERICSSON, of the eity,couuty, and State of New York, have invented an Improved Air-Engine for Producing Motive Power by Heated Air, of which the followingis a full, clear, and exact description, reference being had to the accompanying part of this specification,

drawings, making in which- Figure l is a plan, with the two cylinders,

the. pistons,

of the cylinders, the piston,and the air-heating apparatus in section to exhibit the internal arrangement.

.The same letters indicate like partsin the The heated air, after having performed its olfice in the working-cylinder of mypresent improved air-engine, may be made to circulate through a vessel containing a series of tubes, precisely as in my former engine referred to, and the current of heated air in passing through saidvessel (called the regenerator) may be met by a current of cold air circulating in an opposite direction through the series of tubes on its way to the working-cylinder, by which a transfer of caloric is effected between the two currents of air passing off .-from and entering the -working-cylinder,pre-

cisely as in my said former engine, and the current of cold air on its way'to the workingcylinder, alter having been thus partially heated'by the described process of transferring the caloric, isafterward made to pass through a series of tubes or other vessels exas in my said former engine, or in any other suitable man ner; but although the means adopted for heatingand for transferring the caloric from the escaping to the entering air is quite similar to that invented by me in the year 1833, yet the mechanism or engine which I have now and the air-heating apparatus in; section; and Fig. 2 is a side elevation,with one descriptions and invented for rendering the heating of the air, as described, subservient in producing motive power dili'ers altogether from anything hitherto known. Before, however, describing my invention I deem it proper first to notice, in order that its nature may be correctly understood, that in all air-engines on what is called the differential principle (my improved airengine for which .I obtained patents in 1851, for instance) the motive energy depends solely on the difference of areas of the working and "supply pistons. Experience has in the meantime demonstrated that in order to-obtain a sufiicient supply of air without resorting to a dangerously high temperature the supplypu'mp must be of such large capacity that the difierential (active) area becomes too small. Unless, therefore, future experience should suggest so'meimprovement, the power of such engines will always be, found insntficicnt for practical purposes.-

I will now proceed to dcscribcthe principal feature of my invention, which consists in charging the regenerator and heater-,or either,

with fresh compressed atmosphericair at each, stroke of the engine without the employment of asupply-pump by the peculiar combined movements of two pistons within the workingcylinder, the introduction of fresh air and its transfer to the regenerator or heater in a compressed state being efi'ected under a state of equilibrium .of pressure, so that the supply- .piston becomes entirely relieved .from resistance during the process of charging the regenerator or heater, while at the same time one of thesepistons performs'the office of working-piston, exerting full force on the en-' gine without suffering retardation by any unbalanced pressure against the supply-piston.

My said engine is single-acting, and I connect two of them by a crank-shaft, placing the two cranks at an angle of one hundred and eighty degrees, so that while the piston of one engine is beingimpelled bythe tension of heated air the piston ot' the-other shall be making its returnstroke, and vice versa, and as the two engines are identical in construction the description of one of them will answer for the two. 'lhemanner of connecting thetwo and the ellecls resulting therefrom will be subsequently described.

The cylinder at is open at one-end and has a head, I), at the other, with a central aperture, 0, leadingto a valve-chest, d, with an induction-port,-e, and an exhaust-porn)", fitted with valvesg and h. The stem of-the valveg passes through the'hollow stem of the valve h, and

I these valves are to be operated by any known and suitable valve-gear giving the periods of movements such as will be presently described. The exhaust-port leads by a pipe, 'i, to a chamber, j, surrounding a series of small tubes, k, constituting what has been termed the regenorator, so that the air passing-from the cylinder to the escape-pipe lshall circulate around and among the series of tubesfto impart its heat to the cold supply-air contained within the tubes, and the induction-port communicates with the tubesm of what is termed the heater. The series of tubes 70, constituting the regenerator, are suitably secured to a tube-- sheet, n, at each end, and open into two chambers, o and pthe one, 0, communicating by a pipe,-q,witha port in the side of the cylinder, governed bya self-acting valve, 1", opening outward, and the other, 1), communicating with.

the heatertubes m, which are to be suitably coiled or otherwise arranged to presenta large extent of surface "to. the action of the heat evolved from the fire of a furnace, s, the series of tubes at being placed above the fire, so that the products of combustion in passing to the flue t shall circulate around and among them. The bottom plate of the flue t is a tube-sheet, to which are secured a series of flue-tubes, u, down which the products of combustion pass to a flue, w, below, leading to the chimney.

The flue-tubes u are inclosed ina chamber having an aperture, 1), near the bottom, to receive acurrent of air from the atmosphere, and another aperture, :0, near the top, through which the current of air passes after circulating around and among the flue-tubes by which it IS heated, so that the products of combustion escape into thefat-mos'phereat-a very low temperature, for it will be observed that the two currents'travel inopposite directions, the atmospheric current passing from the coldest toward the hottestends of the flue-tubes gradually absorbing the heat from the products of combustion which are passing through-the tubes'in the opposite direction.

From the passage as the partially-heatedair:

passes down a vertical flue or tube, y, two apertures, 2 and a, both governed by dampers or registers, one leading below the grate in the furnace to supply the fire when having .more "heat is required, and the'other above the fire to admit-the air directly to the heater-tubes;

m when it becomes necessary to moderate the heat of the tubes. By this arrangement a great saving of fuel is efiected and the attendant can control and regulate the heat of the heatertubeswith perfect ease.

To'the cylinder are fitted two pistons, Hand 0. The one, b, is nearest the open end of the cylinder and called the working-piston, and is provided with a s'eli'ractingvalve,

iug inward, and the other, e, termed the supply-piston, is placed between the workingd, openpiston-and tlie head of the cylinder.

supply-piston, are

The rod f of the supply-piston passes through a stufifingbox, e, in the working-piston. -This piston-rod embraces theend of an arm, g,'that vibrates on a fulcrum-pin, h, and the arm carries two rollers, 1', and j-one on each side of the fulcrum-pin h-which rollers, for the purpose of governing the motions of the alternately acted 'upon by two earns, 70 and-l, on the crankshaft m, the earn it acting on the roller and the other, I, on the rollerj. Y v

- In Fig.1 the arm and thetwo cams are concealed on one of the engines, but representedon the other, and in Fig. 2 the'arm. and. its rollers are represented infthe two opposite ex treme positions. The cam k operates on the roller 1; tocarry the supply-piston inwardtoward the head of the cylinder, and the other cam, Z, controls or governs'its motion in the opposite direction when impelled during a part of its movement bytheheat'ed air.

The workingpiston is provided with two wrist-pins, m m'-one on each side of the stuff-" ing box ewhich are taken hold of by two connecting-rods, n n, connected with a vibrating arm, 0, on a rock-shaft, p, which is provided. with another arm, q, at the angle indicated on the drawings, and the arm q'isin turn connected by a rod,'r, with the crank s on the crank-- shaft m, before named.

The required motions are'to beiinparted to the induction and eduction valves by suitable valve-gear taken fore stated, gines are connected with 'one-and the same orank-shaft-,with the 'crankson opposite sides, as the pistons of one are impelled. by theheated air any powerrequired,tocausathe pistons of the other engine to return wiithe derived from i this so'urc'e'if the momentuinjof'the moving parts benot suifi'cientfor thisp'urposer Having describedthe construction o'fon'e of the engines with its regeneratorand heater,

from the crank-shaft, as beand stated thatthe two single acting engines are alike in every respect, as-indiieated bycorand having responding letters of reference, also described inwhat manner thettw'o are connected, I will now'describe the .mode of'op e'ration, assuming that the furnaces oi. the heatershave'been properly fired up.

Byjmeans of a hand air-pumpappli'ed to the chamber 1) at one end of the regenerator,o r any other part of the regenerator or heater-tubes, I

" 'introdnce a supply of atmospheric air at about the pressure of the atmospherefand then the engine is in a conditionto begin its operations.

The cranks should'be turned over or beyond. the dead-point, asusual in steam -englnes. Starting with the pistons of one engine in the position represented in Fig. 2, at the extremityof their outward stroke, as the crank s,

moving in the direction indicated bythe arrow, is making that part of its circuit near the outer dead-point, and therefore imparting but little moti'hn to'the working-piston b, the supply-piston c iscarried from the'workingpiston and toward the head. of the cylinder with and as the two single-acting enand nearthe end gradually a rapid motion by the action of the cam k on being formed as represented, that the piston may be gradually started, rapidly-accelerated, arrested, and there retained in a state of rest as the extremity of the cam passes the roller. During this in ward motion of the supply-piston theworki-ngpiston makes but a small portion of its inward stroke, and therefore the valve df in the working-pist0n will be opened by the pressure of the atmosphere to permit cold air to enter and fillv that part of the cylinder between the two pistons.- So soon as the supply-piston stops the exhaust-port closes and the continued inward motion of the working-piston begins to compress the cold air thus supplied, which of course closes the self actingvalve d, through which the supply was admitted by atmospheric pressure. This supplied cold air continues to be compressed by the workingpiston until the end of the time being from the other'engine it isimportant to observe the condition of the connec tions. l

At the time the supply-piston of one engine is started and the air is entering by atmospheric pressure, and when the arm 0 on the rock-shaftp, with which the working-piston is connected by the rod n, is at its greatest leverage the corresponding arm of the rock-- shaft'of the opposite engine is atits shortest leverage; but as moved inward, and the suppl y-air,'. by reason of being gradually compressed, increases the resistance,'the arm 0 gradually shortens in leverage, and the same arm of the opposite engine gradually and in nearly the same ratio increases in leverage, on the principle of the bent lever, thus applying the power required to compress the supply-air to the best advantage. It should be borne in mind, however, that the power thus applied to compress the supply-air is not actually expended, but merely borrowed, for it is so much added to the elastic force of the air by which, when heated, theengine is impelled.

Just before the supply-piston begins the inward stroke just described, the eduction'valve g is opened, the induction-valveh having been previously closed, so that the charge of heated air by which the previous stroke of the engine was effected ispermitted to escape freely into the atmosphere, so that the power required to move the supply-piston inward is very slight,

the air escaping freely to the atmosphere on one side and entering by atmospheric pressure on the other through the valve d,- but as the heated air exhausts or escapes from the cylinder it passes around and among the series ofsmall tubes it of the regenerator. thus imparting its heat througlpthe metal of the tubes to the cold air contained insideof the tubes,which air is thus partially heated preparatory to be ing finally heated in passing through the heater-tubes. In this way much of the-heat its inward stroke, and as the power' for elTectingt-his compression is derived for [which would be otherwise wasted is saved.

The supply of cold air having been introduced and compressed, the engine-is prepared to be impelled by the expansive force of the heated air. The eduction-valve 9 having remained closed during the greater. part of the inward motion of the working-piston, the inductionair from the heater to the cylinder, by which the working-piston. .The form of the face of the cam Z, as represented, is such as to cause the piston to be carried back with a rapid accelerated motion until it comes nearly'iu contact with the working-piston; and at first in this outward motion of the supply-piston the already-compressed supply-air between the two pistons is still further compressed, not by the power of the engine, but by the elastic force of the heated air, the supply-piston beair from the heater on one side and the cold air on the other, with the self-acting valve 1' (in the side of the cylinder) interposed be? tween the two, for it must be remembered that as the heater and regenerator are in communication the air, which is a perfectly elastic fluid, will be under equal pressure in both, notwithstanding a portion is more highly heated than'the other, and as the supply-air in the'cylinder is simply separated from the air in the regenerator by the interposed valve r in the side of the cylinder the supply-piston will be'moved outward by the heated air until the supply-air is compressed to an equal tension, and then the further motion of the supply-piston, efl'eeted by the cam l' as ita preaches the working-piston,will transfer the supply-air from the cylinder to the regenerator through the valve r. The only power expended by the engine in this transfer will be the small amount required to move the suppl ypiston between two equal pressures to give the slight preponderance to open the valve 7', through which the transfer is made. The moment the supply-piston passes this'valve and overtakes the working piston the preponderance of pressure ceases and the valve closes by gravity. If desired, however, a positive mot-ion properly regulated may be imparted to this valve byasuitable valve-gear. The operations j ust described for the final compression and transfer of the supply-air take place during the time that the working-piston is at rest, or nearly so. It is while the crank is passing the dead-point farthest from the arm q, connected by the rodr withthe crank, and as the crank and the connect-ingrod have their centers of motion at the time of passing the dead-point on the same side of their points of connection, it follows that during the time the crank moves a given distance each side of the dead-point the piston will move through a distance comparatively much shorter-than when the crank moves the point, for in the one case the crank and the valvehis now opened,which admits the heated the supply-piston is forced outward toward' ing, as it were, suspended between theheated to the one necessary same distance each side ofthe opposite dead-,

connecting-rod simplyrepresent the radii of two eccentric circles, while in the other they represent the radii of two opposite circles. By

pelled outward by the expansive force of the heated air and the supply-piston by the catnnoie'ment described.

. The form of the catnl', which acts on the roller j to gover'n the outward stroke of the supply-piston, must be such, as represented, that the piston will move with a rapidly-aocelerated motion until it approaches the work ing-pistointhen gradually retarded, and from the point 1 to 2 its curvature must be such that its motion will be in unison with the motion 'Ii'mparted to the working-piston, by'reason of its connection with the crank, modified by the interposition of the arms. 0 and q, operating on the principle of the bent lever.

It has been shown that the alternating leverage ot' the arms 0 of thetwo engines is such as to apply the power for compressing the supply-air to the best advantage, and it remains to show the connection between the two in furtherance of t his'e'conomy. It will be seen that the arm 01', connected with the working-piston fllfllng th' outward stroke, gradually increases in letterage asthe heated air, by dilatation, .gradully decreases in tension. Now the-leye'i'agept' this arm gradually increases dn ring the outward stroke of the working-piston of one: engi heas it gradually decreases in the other' engine', where the Working-piston is compressing thesupply-air', and vice versa.

Iniias'been stated that the power exerted on the workingpiston to compress the supply-air was not an actual consumption, but a mere tran'stjerofipewer. This will beapparent from the description. of the entire operation, be cause the air thus compressed is transferred to the regenerator and from the regenerator to the heater, andthence to the cylinder, where it exerts on the piston the elastic force first impressed upon it by the piston, together with the tensive force which it has acquired by being heated, so that the compression which it received at first from the piston when working in one direction it returns to the piston when working in the'opposite direction under the advantages due to the arrangement of the two engines, as above specified.

By the alternate strokes of each engine the required supply of cold air is introduced, compressed, and transferred from the cylinder to the regenerator, carried through the regenerator, thence through the heater, and from the heater back to the cylinder, and in this circuit it is, grad nall-y heated, first by the heat which it takes up from the escaping heated air, and then by the heat of the furnace, and as atmospheric air is a bad conductor of ca- 1or ic,the heat will not be carried back by condnction from the heater to the regenerator, but after the heated air has exerted its elastic force in the cylinder in escaping it transfers its surplus heat to the supply-air on its passage through the rcgcnerator. The object of the regenerator being, however, merely that of economizing fuel, it is evident that the supply-air may be passed directly from the cold end of the working-cylinder, by the action of the supply-piston, to a heater communicating with the other end of the working-cylinder.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The method of supplying fresh air to the engine, compressing and transferring it to the regenerator and'heater,'or either, by the action of the supply and working pistons within the one cylinder, operating on the principle and in the manner substantially as herein de-- seribed,whereby the air is admitted under at- 'mospheric pressure as the supply-piston is moving from the workingpiston as the previous charge of heated air is exhausting, so that-the said supply-piston moves in equilibr'ia, or nearly so, and bywhich, also, the sup ply-air is finally compressed and then transferred the regenerator and heater, or either,;as

the snpply-piston moves between the supplyair and heated air during the period of the nearly stationary position-of the working-piston. I

2. In combination with the double-piston movement of each cylinder, the method ot'connecting the workingpistons oftwo single-acting engines to constitute a double-acting engine by means of two sets of vibrating arms attached to each other and vibrating on a common center connected with the two workingpistons, and with the two cranks on opposite sides of the axis of the crank-shalt, the two sets of arms operating on the principle of the bent lever, and the crank-shaft being so located relatively to the cylinders and the centers of vibration of the arms, substantially as described, that the Working-piston shall be at the end of its inward stroke at the time the crank is passing the dead-point farthest from the point of connection of the connectingrod with the vibrating arm, as described, by which the power of that working-piston which is being impelled by the heated air is applied to the best advantage to operate the other working-piston during its return-stroke, and by which,also, the working-piston reinainsnearly at, rest during the time the supplypiston is making that part of its outward stroke during which the partially-compressed air is finally and fully compressed and transferred to the regenerator and heater, or either, as described.

Witnesses:

WM. H. BISHOP, ANDREW 'DE LACY.

ERIGSSON.

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