US824A - Construction of steam-engines - Google Patents

Description

N.FETERS. PHOTO-LITHGRAPHER, WASHINGTON. D. C.

NA'IHANIEL` BOSWORTH, OF PHILADELPHIA, PENNSYLVANIA.

Specification of Letters llatent No. 824, dated July 9, 1838.

To all whom t may concern.'

Be it known that I, NATHAMEL BoswoRTH, of the city of Philadelphia, inthe State of Pennsylvania, Vhave invented cert-ain Improvements in the Manner of Constructing Steam-Engines; and I do hereby` declare that the following is afull and exact description thereof.

My first improvement consists in the manner in which I construct land set the boiler or boilers and connect them with ,the` pipes for the conveyance of steam, and the auxiliary parts of the engine. The boilers which I employ are of the cylindrical kind, and they are to be so -set `as that they may be completely `surrounded by the flames and heated air from the fire, and have their Awhole surface, therefor, converted into a fire surface, instead of exposing one half, only, of the boiler, to the direct action of the heat as is usually the case. It is well known that, `even where t-he best precautions are used to prevent it, a large portion of heat is lost by radilication, from that part of the boiler not exposed to the fire; a loss which is entirely obviated by my plan, as the boiler is, over its whole surface, made a recipient of heat, by being constantly encompassed by a medium hotter than itself. It has been satisfactorily ascertained that thisview of the subject is not a matter of theoryv only,

but that the quantity of steam produced byV the combustionof a given quantity of fuel, is much increased byl this arrangement. These boilers, as they are to be entirely surrounded by the fire, are to be kept completelyfull of water, land are not, therefore, subject to burn out. f a y Figures 1 and 2 in the accompanying drawingrepresent the form of the boilers, and the mode of sett-ing them, as shown in Fig. 1, two or more boilers are supposed to be used, placed side by side. y

A, A, shows one of the boilers, in section. These boilersare to be so set as to form a considerable angle with the horizon, rising from their front toward their back ends,`

abut one inch in a foot; `by which elevation the steam willV be caused to escape readily from the boiler into the steam chamber or receiver at its upper end.

B, B, is the receiver, and is connected with the force pump; the dotted line I) being the water line, at the level of the upper edge of the boiler; the space above D being the steam chamber. Y E 1s a water pipe connecting "the boiler C, a steampipe connectingthe top of the boiler` with the steam chamber.` 1 i F 1s the re place, and G the ash pit; Il,

H, the open space surrounding the boiler, y

Vwith the lower part of the receiver; andC, w

and I the flue leading to the chimney. .The Y steam pipes to conduct the steam `from the receiver to the cylinder, should not enter the pipes C, C, but should, in all cases open into the top of the receiver between these pipes. IVhen the steam chamber and connec- 1 x p tions are thus arranged, it will be found that there is a `complete separation of :the water from the steam which may be intermiXed` in` passing from the boilers to the receiver.

\ When a single boileronly is wanted, itis '5 tof be set in the same manner as when two or moreboilers are employed, but lnstead of the receiverwhich 1s used to connect several boilers, I make a steam chamber in theman- H; 4

ner shown iny Fig. 2 where A,\A,` isthe boiler, and B, B a continuationthereof, rising vertically. The dotted line D, is the water line, Hthe steam pipe leading to the i cylinder,- I, the water supply pipe, and K the safety valve.

The steam cylinder, with its stuffing box, and piston, represented inv Fig. 3, has nothing in it peculiar excepting the construction ofthe piston, which is ma eof metal Ain one piece Vand withoutv packing. "It may be formed of hard cast-iron, o-r of cast steel, and must be finished perfectly true and smooth. Its diameter is to be such thatwhen its temperature is raised one hundred degrees above that of the cylinder, it .will still'pass through it readily, but leaving no sensible space between t-he two; when of the vsame `temperature with the cylinder itwill of course pass through it loosely. U to a diameter of four inches I think it leave the piston perfectly solid, but if above this size it may be made hollow, for the purpose of decreasing its weight. Such a pisparent friction beyond that which necessarily exists in the passing of the piston rod through the stuffing box, and the most careful observation leads to the conclusion that there is not any loss of steam between the est to `ton I have found to work without any apy piston andthe cylinder andif there is any,

C is intended to illustrate the principle upon which the valve operates. That which characterizes this valve is its being so con Y structed as to possess the property of'shutting oif the steam at a half or any other given part of the stroke, this effect resulting from the relative proportion of its respective parts, without its being complicated by 1 any addition thereto.V The ordinary value,

moved by an eccentric, is usually made wwithout reference to any particular proportion between the face of the valve andthe steam Y passages, the eccentric being set at right angles or nearly so, to the crank, constituting what is usually termed a whole stroke valve, letting the steam on soon after passing the center on one side of the piston, the steam which caused the preceding stroke escaping simultaneously, or nearly so. The valve shown in Fig. 4, is so proportioned as to shutoff at half stroke; which is eifected, first, bythe proportion between the valve faces and the induction passages which they Y alternately cover, without regard to the center passage; and secondly, by the peculiar position in which the eccentric is set to the cranks, this in the instance given, being forty five degrees from the line of the crank,

instead of ninety; and as much less, or nearer to the line of the crank, when the proportion is altered so as to shut olf at one third, y

or one fourth of thel stroke.

The valve as shown in the drawing, is supposed to be moving in thev direction Yof the exceeding in distance the extreme of variaarrow and to have accomplished threefourths of its motion, measuring on the cirl cumference of the diagram (c) from a to b the crank having just passed the center, and the piston being moving in the same direction with the valve, is in the act `of receiving i steam as will be seen by inspecting the valve. This motion of the valve being confrom b to c; the motion of the valve will middle, or eduction passage.

nection between the eccentric and the valve; but this is of no consequence to the understanding of the operation provided it be borne in mindV that the valve and piston are supposed to be moving in the direction of the arrow. The stroke of the piston being completed, a like eect will be produced in that which succeeds it in the opposite direction. It will be seen by inspecting the diagram C, that the steam is leton the pistonV Yduring the course of one fourth of the entire circle, as from c to cl; the peculiar properties of this valve being derived fromthe quadrature of the circle. i

To arrange the valve to shut off at a third of the'stroke, there needs no other change than an addition at each end of the valve, corresponding with the distance, or space, from e to f, and a slight difference in setting the eccentric a little forward, so as to permit 'the valve to open when the crank is on, or a little past the center. It will be observed, in this latter case, that the size of the steam passage willV be diminished beyondY the numerical proportion, but it is also toV be reco-llected that the piston, when near the center, is moving at a comparatively slow rate; and the'speed will be found, by calculation, or upon inspection, to be in the exact ratio ofthe diminution of the passage.

Fig. 5 represents my improved water in* dicator which shows the height of the water in the boiler, by means of a glass tube of the usual form, butk so arranged as not to become heated by the steam or water. of the boiler. C, C is a water pipe connecting the llower part of the boiler A with the 4glass indicator tube D; and B lB is a tube connecting the steam chamber with the upper'end of said glass tube. The water tube C, C is bent down at X, in the manner shown in the v drawing, a descent being given to this bend the boiler cannot descend sov as to mingle 1 with the water in the leg i Y, and consequently the water in this leg, in the tube C, and in the glass indicator, must be kept at a temperature but little, above that of the sura rounding atmosphere; the only' heating tinuous will be completed on its arrivalY at the place of the dotted line on the right,E while the motion of the eccentric will be;

cause to which it issubjected being from the conducting power of the tubes; and the water produced by the condensation of the smallk portion of steam which rst enters the tube B. The length of the tube B, as drawn in the figure, is six feet; four feet ofY it, next toward the glass being half an inchl in diameter, and two feet of the portion B, next to the boiler, being two inches in diameter; the proportion being such that when all the atmospheric air in the portion B, is driven into the half inch tube B, the pressure will be equal to 240 lbs. to the square inch; the steamtherefore, cannot nd its way into the smaller tube, and as air will not conduct heat downward into the indicator, it must remain comparatively cold, while is performs its oiiice perfectly; Vthere not being any apparent tendency inthe steam and air to intermingle. v

It will be proper to remark that what I have called the receiver diEers essentially from what is usually denominated a steam drum, the oce of the latter being that of a steam chamber only, while my receiver is .always to contain water to the same height in which it exists in the boiler, with which it is connected for that purpose; this vessel, in my engine, receiving also the requisite water from the supply, or force pumpsyits construction for the purpose of performing these respective oices, give to it a character essentially new, distinguishing it Yfrom the ordinary steam drum in a manner which must be perfectly apparent.

In the improvements above described `I have had in view mainly, to attain a higher degree of speed than has hitherto been thought eligible in the reciprocating engine.

It is now an admitted law in mechanics, thatfriction is as the time; and it is mani-V fest, therefore, that if'an engine can beso. constructed as greatly to decrease the weight :of its moving parts, and greatly to increase the speed with which it moves, there must,

from the saving of resistance from friction, alone, be very important advantages ob` tained. I have succeeded in practice, in

working the piston of my engine at a speed of upward of two thousand feet per minute,

and have thus produced e'ects at least five` fold greater than has ever, heretofore, been produced by engines of the same weight.

I am aware that I cannotclaim the increased speed of which my engines admit, in the abstract; but I do claim it in combina- 3. I claim the constructing of a metallic piston, to move without friction inthe manner set forth. I do not claim to be the first to have used a solid metallic piston; but I do claim to be the first who has used it so asto pass through the cylinder without friction; having been the first toA ascertain that this might be done without a waste of steam. 4. I claim the manner of constructing and using the receiver, when two or more boilers are employed,.as herein fully made known.

5. I claim the manner in which I haveconstructed my indicator and connected and combined the same with the boiler substantially as described lastly.

6. I claim -the particular construction of the slide valve as set forth for cutting off the steam at any designated part of the stroke of the piston; this result being obtained bythe particular proportion of its parts `without resorting to any greater complexity of construction than in the ordinary whole stroke valve.

NATHL., BOSWORTH.

Witnesses L. BANGER, JUDAH DoBsoN.

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