US11117A - High-pressure steam-engine - Google Patents

Description

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i BENJAMIN CRAWFORD, OF PITTSBURGI-LPENNSYLVANIA.

' `I-IIIGrI-I-PIRESSURE STEAM-ENGINE.

minish the power consumed in working the` condensing apparatus of steam engines, lessen its bulk and the cost of constructing it without diminishing the power of the engine. The attainment of this object has long been a desideratum, more "especially -in engines used in propelling vessels, because every pound saved in the weight of the engine adds proportionally to the capacity of the vessel for carrying freight, and by increasing her buoyancy lessens the resistance of the water to her motion and enables her to sail faster with a given consumption ofl fuel. In so much has it been the object of river Steamers to obtain cheap and light engines that they have, on our western rivers,

long since dispensed with the use of the condensing apparatus altogether.

`My invention consists in shutting off the communication between the cylinder and the condenser an instant before the steam escapes from the cylinder when the piston has made its stroke, at the same time making provision, by means of a valve placed in the exhaust pipe, for the steam to escape into the atmosphere without resistance, which escape continues as long as the elastic force of the exhaust steam is above the atmosphere, which is but a moment of time, when the communication is again opened to the con-` denser. Egress to the air being at the same instant closed by the operation of the `valve in the exhaust pipe, the piston travels in a vacuum in the same manner as in the ordi- 4nary condensing engine. By this operation no matter how great the pressure of steam in the cylinder when the exhaust takesplace there will only be a cylinder full of s team at the pressure of the atmosphere to condense. Thus if the engine is working at full stroke with steam of eight atmosphereswhich is no uncommon pressure for steamboats on the western waters-seven eighths of this steam would, by my improved plan,

Specification of Letters Patent No. 11,117, dated June 20, 1854.

be suffered to `escape into the atmosphere,

leaving only one eighth to condense; thereby reducing the size of the condensing apparatus in about the same proportion, as well as in like manner diminishing bulk, weight, and cost, and also the power required to work it, and this to any one conversant with the steam engine is sufficient evidence of the importance of my invention.

The l great value of the objects I have sought to attain by means of these improvements has been so long known among engimade to secure them by other means. One

of these was essayed by myself and for `which I obtained a patent, dated the seventh day o-f September, in the year 1844, but on trial, although it possessed some advantages,

I found it inadequate to produce the results obtained by this improvement. In stationary engines where the bulk and weight of apparatus, although highly objectionable, is

less so than in marine engines, it has been proposed torelieve the main condenser partially of its duty by means of a supplementary condenser in which the heat evolved by the steam was applied to economical uses, such as the boiling the works in distilleries orbreweries. So far as the two objects of boiling by the steam and the condensation of the steam are compatible up to that point the supplementary condenser will relieve the main condenser, but when the liquid to be heated in the supplementary condenser reaches the boiling point the main condenser would be required to perform full duty, just as if it was not at anytime assisted by a supplementary one. Under these circumstances `the size of the main condenser could neers that numerous attempts have been not be diminished, for unless it was relieved all the time of aportion of the duty of condensing, it might as well not be relieved at j whereas the other contrivance, in addition to the ordinary condenser of full` size, and which at times has, as stated, to do full duty, has a supplementary condenser of greater or less bulk, which at times relieves the main condenser, more and at other times less, but

never allows the steam to escape through it by a free passage into the atmosphere. This therefore involves a more bulky condenser than is ordinarily employed, while mine in- 'volves one less, bulky, and this is the difference not only between my present condensing engine and that I have just described, but it is also the differencebetween it and all others, including the one mentioned which I patented in 1844;, which could not be diminished in bulk, as I expected, because that p rtion of the steam which I 'suffered to es' mounted by` a valve-chest and exhaust pipe (B) made in any of the well known forms. The exhaust pipe (B) terminates in a Valvechest (F), in which a communication with the condensing chamber (I) is opened and closed by a valve (c) operated bythe toes (e e) of a rock shaft through a lever (Gr) andy valve stem (d), constructed and arranged in any well known or convenient manner. On the upper side of the exhaust pipe a communication opens with the atmosphere through the pipe (C), which may pass through the reservoir of feed water to heat the same. This communication at a point near the exhaust pipe is fitted with an escape valve (b) that opens outward, and which may be opened by the pressure of the steam from within when the exhaust valve is opened and closed by the pressure -of the atmosphere from without when the condenser is open; or it may be opened and shut mechanically at the proper time wit-hout resistance by motion derived from any of the moving parts of the engine; but whether it be opened and shut by the reciprocal action of the steam and atmosphere or by the engine it must be opened the instantthe exhaust valve of the engine is opened, to let that portion of the steam which is above the pressure of the atmosphere escape, and when this has been accomplished the communication between the exhaust pipe (B) and the condenser is opened by. raising the valve (c) as the entrance to the condenser, when the escape valve (ZJ) should` shut to prevent the air from rushing in and vitiating the vacuum. lThese conditions continue until the piston reaches the end of the stroke, vwhen the valve at the entrance of the condenser is closed, so that upon the eduction valve at construction of condensers in all their parts,.-

is well known, I have not deemed any milf;` nute description of the one represented here necessary. For the same reason I have omitted to describe the construction of the cylinder and piston, the valves with their seats and the chambers in which they are placed and the pipes with which they are connected.

I have described but a single mode of arranging my improved condenser with respect to the engine and but one plan of colnstructing it, but itis obvious that its construction and arrangement may be as various as that of the steam engine itself without the least departure from the principle of my invention, and I contemplate making all the changes o-f the character above indicated that may be found expedient in adapting my improvement to different circumstances.

Having thus explained the nature of my invention, and the manner in which it may be applied I would state that an engine is described in the Mech-@nids Magazine, vol. 36, pp. 33 to 36, for a purpose similar to that of my invention, where the exhaust steam escapes against the pressure of a spring. This forms no part of my invention, but

What I claim is- The method of producing a vacuum in condensing engines by allowing a part o-f the exhaust steam to escape into the atmosphere without resistance by a flap valve as described before the condenser is opened and then condensing the remainder by o-pening the communication between the cylinder and condenser whereby the weight, bulk, cost, and expense of vworking the condensing apparatus are diminished, and the power and eticiency of the engine are increased l Witnesses: Y

A. B. SToUGHToN, JOHN L. SMITH.

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