US470664A - Steam-engine - Google Patents

Description

, (No Model.) 1' 2 sheets-sheet 1.

' H. J. CONANT.

STEAM- ENGINE.

No. 470,664. Patented Mar. 15, 1892.

WITNESSES. UVVE/VTOR:

1m; mms Pn'zns ca. mow-mun; WASNINDTOH, n. c.

(No Model.) 2Sheets-Sheet 2.

H. J. GONANT. STEAM ENGINE.

No. 470,664, l Patented Mar. 15, 1892.

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. high-pressure cylinders, and have for their the fact that for each cylinder or set of cylin- STATES PATENT OFFICE.

HENRY J. CONANT, OF WATERTOWN, MASSACHUSETTS.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent N 0. 470,664, dated March 15, 1892.

Application filed December 3, 1890.

To all whom it may concern:

Be it known that I, HENRY J. CONANT, a citizen of the United States, and a resident of Watertown, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Steam-Engines, of which the following is a specification.

My improvements relate particularly to compound and to multiple engines, by which latter I mean engines having more than one cylinder, whether compound, multiplex, or all object an increase of efficiency on light loads not, I believe, heretofore satisfactorily attained.

To these ends it consists in the method of controlling and regulating the engine and in the apparatus for effecting my method, constructed, arranged, and combined in the manner hereinafter shown, described,and claimed, reference being had to the accompanying drawings, wherein Figure l is a side elevation of a complete engine of the triple compound type; to which my invention is peculiarlyadapted, and shows one application of my device. Fig. 2 is an end elevation of the same. Fig. 3 is a diagrammatic sectional View of the same. Fig. 4 is a plan view of a slightly-modified form showing my automatic attachment, and Figs. 5 and 6 show the details of one form of automatic device 5.

for accomplishing my method. a

In the several views like letters of reference indicate like parts. p

In engines of the multiple type, by which, as above noted, I include all engines having more than one cylinder, on reduction to light loads a great decrease in efliciency and consequent loss of power ensues. This is due to ders, owing to its relation of parts, a maximum efficiency is attainable at but one steampressure and cut-off. Below this pressure or at other points of cut-off the efficiency rapidly falls till at half-load, in many cases two-thirds, the full coal consumption is required. By my invention, however, I cut off the live steam from one or more cylinders and thusam enabled to run the remaining cylinders at conditions corresponding more nearly to their 1 maximum efficiency. To prevent the cylin- Serial No. 373,395. (No model.)

ders so cut out from unnecessarily wasting power, I close their exhaust-ports, and after admitting the requisiteamount of air the pistons run smoothly and noiseless with the aircushions so formed. I further provide an automatic means for doing this, of which one form is illustrated in Figs. 4, 5, and 6.

For convenience of illustration I have preferred to show my invention as applied to a triple single-acting compound engine, and for the purpose have selected the type known as the triumph compound. This engine being well known, it will only be necessary to give a cursory description of its operating to my invention. The three high-pressure cylinders H H H" areshown cast in a single piece with the three low-pressure cylindersB B B". The pistons for each pair of high and low pressure cylinders are formed in a single piece, having the flange C, formingthe low-pressure piston and containing the several steam-ports. The cranks are set at an- 'gles of one hundred and twenty degrees. Each piston contains valves for the control of the next succeeding cylinder. Thus for the high-pressure cylinder H, which in Fig. 3 is about to receive steam, the admission is from the main D to F in piston H through fixed port G .into high pressure admissionfrom H into the" lowpressure cylinder B.

This is effected through It and the fixed port I. It will be seen that the opposing ports of h and I have been shown in a plane with those of G and F. This cannot so be in pracport It. 'As shown, admission is just beginningin H, while expansion is about to begin tice, since h would also open into G at another phase of the stroke. For convenience of illustration, however, these ports are shown distorted into the plane of sectionJ-l From the relative positions and movements of theseveral pistons it is clear that the low-pressure cylinder B should be about to exhaust while B" should be at full exhaust. The former takes place through I and the moving port J" into the exhaust pipe K4, the latter through I and J into exhaust-pipe K. Since the pistons of H and lare in like positions, though moving in opposite directions,

it follows that as expansion from H to B is just beginning by the movement of the pis ton in 1-1 compression in H" and expansion on cut-off in B are also just commencing.

For admission it will be seen that the admission-ports h h h" must be open, as well as the respective controlling-valves F F" F, and in this manner admission on the return stroke is prevented, the piston-openings not then corresponding. Further explanation of these valves is unnecessary, since like letters of referenceindicatelike parts and the primary and secondary signs indicate the respective cylinders, and also because they form no part of my invention.

M indicates the shaft; N, the cranks, arranged at angles of one hundred and twenty degrees apart, and O the connectin rod, which is pivoted in a recess in the piston, and

therefore its attachment does not show in the figure.

I will now explain myinvention as applied to this form of machine. D are my supplemental throttle-valves placed on the several steam-pipes. These enable me to shut off steam separately from each high-pressure cylinder, and so also from the corresponding low pressure. The three cranks will, when one pair or set of cylinders is thus cut out, allbe still steam-actuated, as the high pressure so cut out acts on a different connecting-rod from the corresponding low pressure. I also find it advisable to place valves K' on my exhaust-ports and close the exhaust after closing a corresponding steam-pipe. I also find it advisable to admit air to these disused cylinders, that proper cushioning may be effected. This I find is best done by adding the petcocks P, connected with the high pressure cylinders at a determinable position in the stroke. By this means I am enabled to establish a cushion of air equal to the volume of air at atmospheric pressure required to fill the cylinders at the instant of compression.

After allowing this condition to establish itself I close the petcocks. This engine then runs at about two-thirds load with the full boiler-pressure and with but little loss of energy in the idle-cylinders. In the view shown in Fig. 4 the steam-pipes leading from the throttle to the several ports are shown outside the machine-frame, while the exhaustports do not appear at all. In Figs. 1 and 2 thesesteam connections are inclosed in the machine-casi ng,'while the several exhausts are shown outside and opening into the main exhaust L. shown in Fig. 2.

In Figs. 4, 5, and 6 means for carrying out my method of control and regulation. R is a valve for closing the steam-pipes D, though my device may be,-and better is, applied also to the exhaust. P is a piston working the valve-rod and inclosed in The cylinder S has the the steam-cylinder S.

two ports 8 s, which are operated by the slidevalve U in snugly-fitting valve-case T, closed at each end.

One end receives the pipe t,

The usual throttle-governor is is shown an automatic connecting with the live steam in pipe D. On this end therefore of this piston-valve U the effective initial pressureon the engineacts. On the other a helical compression-spring, inclosed by the head V and surrounding tube t, gives counter-pressure. The tube t forms a piston-rod for the valve U and projects through the other head V of the valve-case. In the piston-valve U are the two steamways u u, separated by a space equal to that between the openings 5 s in the corresponding valve-seat. The way u is separated from the steam end of the valve by an equal space and communicates with the open air-tube 15, while the way uis connected with the steam end of the valve. Thus to is an exhaust and to a steam-passage for the piston P. The space T, communicating with the atmosphere by a restricted orifice in the head V, forms a damper for the valve U. The modus opercmdz' of this automatic form of my invention is as follows: Suppose the engine to be at rest and it is desired to start it under full load at boilerpressure. In such case the valve U will be at the start pressed firmly against the steam end of the valve-case, being in the position shown. When the steam is turned on, the pressure throws the valve U to the other end of the cylinder. Port 3 comes opposite it, while port-s, clear of the end of the valve U, receives steam from t. This throws the piston P to the left and opens valve R for the full admission of steam to the corresponding cylinders of the engine, the air in S making its escape through 8, a, and t.

At a given speed and efficiency the work done by the engine is proportional to the effective pressure and the number of cylinders taking steam, and as this work falls off under lighter loads the steam is reduced by the throttle of the governor. If the work is reduced to less than two-thirds, it is obvious that two cylinders would do the amount required more efficiently and at a pressure more nearly that of the boiler than all three. It is also obvious that the initial pressure will have fallen to somewhat less than two-thirds the boiler-pressure, the reduction being effected by the governor and throttle. The spring of my automatic device is so adjusted that as the initial pressure falls the valve U is advanced until on a reduction of load to less than twothirds this advance is sufficient to bring the valve to 'the position shown in the drawings.

Steam is then admitted through to and s to the left of piston P, and the piston is thereby driven to the right, closing valve R and cutting off one pair of cylinders. The exhaust mean-while from S is through 5-, u, and If. The closure of valve R tends to retard the engine; but the opening of the throttle by the governor brings up the initial pressure to counteract this effect. Two cylinders will now do the work just previously done by three, and it is clear that since two cylinders at full boiler-pressure will do just two-thirds the work that three do on less than two-thirds load the pressure admitted to the cylinders will be somewhat less than full boiler-pressure, the reduction being produced by the throttling of the governor. When the boilerpressure is admitted to the cylinders, it is clear that as at first the valve R will he reopened and all three cylinders thrown in, after which the governor will reduce the initial pressure as required. The momentary rises and fallsof pressure upon the opening-andclosing of valve R are prevented from actuating the automatic valve U by the damping device formed by the air-cushion behind the valve U. There is of course a fluctuation in pressure during each ad mission; but as this is not more than perhaps one twenty-fourth of a second to, say, two hundred and forty revolutions it is ratheramere vibration. W hatevereffect of this reaches the piston-valve Uis taken up by its inertia and has no resultant effect.

From the foregoing it will clearly be seen that by my device one cylinder may be cut out on a reduction of load to somewhat above one-half, and again out in by rise of the effective pressure to as near that of the boiler as desirable. It will readily be understood that a 'like automatic valve may be placed on a second steam-pipe and so reduce the engine to one-third for lighter loads; but as this is but repetition I do not set it forth at length. It is equally clearthat this device and my whole method is equally applicable to any system of engine or engines run as one, in which more than one high pressure is or may be used, as in types when two cylinders are compounded or used separately, according to requirements, and by the term high-pressure cylinders in the claims I include such. Moreover, while I have shown an automatic controller or go vernor operated by the effective steam-pressure it is evident that many well-known electrical,mechanical, pneumatic, and other devices may in similarmannerbe actuatedbythepressureand made to perform substantially the same functions in regard to valve R. It may also be noticed here that I have not shown any drip-cocks or other means of disposing of the condensed steam in my controller, nor specia means for preventing the formation of a vacuum. The latter Will, however, be unimportant if the piston P be not too tightly packed. It is also clear that my method may be applied to regulation by cut off with mere mechanical changes. All these various modifications. I desire to cover by this patent.

By the term exhaust-pipes I include the ultimate exhaust connection in compound or multiple expansion engines and the usual ex haust of the simple high-pressure types. This is usually the connection with a condenser, though sometimes into the atmosphere.

I have shown one form and application of my apparatus and method as self-operating and the apparatus for manually accomplishing the same results, and therefore I claim, broadlyautomatic controllers or 1. In a multiple engine, the combination of steam-main, steam-pipes leading to the several high-pressure cylinders, one or more valves D in one or more of the said several steam-pipes, one or more valves in the several exhaust-pipes, and the pet cock or cocks P for the several cylinders, substantially as set forth.

2. In a multiple engine, the combination of the steam -.main, a throttlevalve therefor, steam-pipes connecting with the several highpressure cylinders, one or more supplemental steam-throttle valves in the several steampipes, and one or more corresponding supplemental valves in the several exhausts, substantially as set forth.

3. In combination, in a multiple engine, the steam-main, steam-pipes, and exhaust-pipes for the several cylinders or sets of cylinders, oneor more valves in same, and one or more governors therefor, substantially as set forth.

4. In combination, in a multiple engine, the

steam main and governor therefor, steam and exhaust pipes for the several sets of cylinders,

one or more supplemental valves therein,

and one or more controlling devices for said valves operated by the effective initial pressure, substantially as set forth.

5. In combination, in a multiple engine, the steam-main and throttle, the governor therefor, steam and exhaust pipes for the several sets of cylinders, one or more valves in the said pipes, and one or more steam-controlled mechanisms for operating said valves, substantially as set forth.

6. In combination, in a multiple engine, the steam main, throttle valve, and governor, steam and exhaust pipes for the several sets of cylinders, one or more supplemental valves in the said pipes, and one or more automatic valve-controllers therefor, consisting of a piston P in a cylinder S, connected with the valve to be controlled, ports 8 s therefor, a slide-valve U in a case T for the said ports,

operated by the steam at effective initial pressure and cont-rolling the admission and exhaust of steam from ports 3 s, and a counter-spring therefor, substantially as set forth.

'7. The method of increasing the efficiency of multiple engines onlight loads, which consists in reducing the number of cylinders taking steam and increasing in similar proportion the quantity (or volume into pressure) of steam taken by the remaining cylinders, substantially as set forth.

8. The method of increasing the efficiency of multiple engines when running on light loads, which consists in reducing the quantity of steam taken by one or more cylinders and increasing that taken bythe remaining, substantially as set forth.

9. The method of increasing the efficiency of multiple engines on light loads, which con sists in cutting off on reduction of load the high-pressure steam from one or more of the cylinders and increasing the quantity (or volume-pressure) acting on the remaining cylinders, substantially as set forth.

10. The method of increasing the eiiiciency of multiple engines on light loads, which consists in cutting off the steam and exhaust from one or more cylinders or sets of cylinders and increasing the initial pressure on theremaining cylinders, substantially as set forth.

11. The method of increasing the efficiency of multiple engines on light loads, which consists in actuating a valve by the decrease of initial pressure, cutting ott steam thereby from one of the cylinders, andincreasiug the initial pressure on the other cylinders, substantially as set forth.

12. The method of increasing the efficiency of multiple engines on light loads, which consists in actuating a valve or valves by the decrease of steam, reducing thereby the steam taken by some of the cylinders, and increasing that taken by the others, substantially as set forth.

In testimony hereof I affix my hand this 29th day of November, 1890.

HENRY J. CONANT.

WVitnessesr J. M. WHEAToN, W. E. MANSFIELD.

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