US459779A - Compound engine - Google Patents

Description

(No Model.) v 2 Sheets-Sheet 1.

l F. W. DEAN.

COMPOUND ENGINE.

2 sheets-smet 2.

(No Modl.)

I'. W. DEAN. GOMPOUND ENGINE.

No. 459,779. Patented Sept. 22, 1891.

Uitz

A* un H Witnesses:

250m-.er

lwefnor: Francis WnHaro 0W @ma Peam I 3 Attorney.

UNITED STATES ATENT OFFICE FRANCIS IV. DEAN, CF CAMBRIDGE, MASSACHUSETTS.

COMPOUND ENGINE.

SPECIFICATION forming part of Letters Patent No. 459,779, dated September 22, 1891.

Application tiled May 29, 1891. Serial No. 394,501. (No modeLl;

To all whom it' may concern:

Be it known that I, FRANCIS W. DEAN, of Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Compound Engines, ot' which the following', taken in connection with the accompanying drawings, is a specification.

My invention relates to compound engines of that class in which, in starting, live steam is simultaneously admitted to both cylinders in order to obtain greater pressure at starting, and also to obviate the ditliculty sometimes met of having to apply manual power to start the engine when steam is admitted first to the high-pressure cylinder only and the high-pressure crank happens to be on one ot its dead-centers.

My invention is an improvement upon the invention described in the Letters Patent, No. 433,164, granted to me July 29, 1890; and it consists in certain novel features of construction, arrangement, and combination of parts, which will be readily understood by reference to the description of the drawings and to the claims hereinafter given, and in. which my invention is clearly pointed out.

Figure l of the drawings is a vertical transverse section through the smoke box of a locomotive-boiler andthe two steam-cylinders ot' a compound engine illustrating my invention on line l l on Fig. 2. Fig. 2 is a sectional plan of same, the cutting plane being on line 2 2 on Fig. l, the steam-chest and covers being removed. Fig. 3 is a plan of the forked section of the pipe connecting the high and low pressure cylinders. Fig. 4 is a plan of the converting-valve casing. Fig. 5 is a vertical section on line 3 3 on Fig. 4. Fig. 6 is an inverted plan of the lower head of the converting-valve casing and the inlet-pipe for live steam. Fig. 7 is a plan of the intercepting-valve casing. Fig. S is a vertical section on line 44 on Fig. '7. Fig. 9 isa horizontal section on line 5 5 on Fig. 8 and showing the valve in plan, and Fig. l0 is an inverted plan of the upper head of the intercepting-valve casing.

In the drawings, my invention is illustrated as applied to a locomotive, only so much ot said engine and its boiler being shown as is necessary to illustrate my invention, but the principal features ot inyinvention are equally as applicable to stationary as to locomotiv engines.

In the drawings, A represents the shell of the locomotiveboiler, and A the tube-sheet at the rear ot' the smoke-box.

B is the higlrpressure cylinder, B its saddle, B2 its steain-chest,and Bsthesteam-chest cover. l y

C is the low-pressure cylinder, C its saddle, C2 its steam-chest, and C3 the steam-chest cover.

I) is the steam-supply pipe through which live steam passes from the steam-dome to the steam-chest of the high-pressure cylinder.

B4 is the exhaust-passage of the high-pressure cylinder, to the upper end of which is connected the casing E, which is provided with the curved pipe E. The upper end ot the pipe E has secured thereto the single arm E2 of the forked curved section, the ends of the two arms E3 and E4 of its fork having secured thereto the two enlarged receiverpipes E5 and E, respectively, the lower ends of which communicate, respectively, with the supply-passages F and F, leading to the interior ot' the low-pressu re steam-chest C2, as shown in Figs. l and 2.

lr isthe exhaust-passage of the low-press u re cylinder, communicating at its upper end with the exhaust-pipe G', of usual construction.

So far the construction is the saine as shown and described in my previously-cited Letters Patent, except the casing or chamber E in the pipe, through which the steam exhausted from the high-pressure cylinder passes to reach the low-pressure cylinder, which casing is made with an open top, to which is bolted the casing II, provided with the inner pendent tubular hub I'I, which extends into the chamber E, and has its upper end closed by the dome-like cap II2. out to form a cylinder having two different diameters, the upper portion IIi being the larger and having fitted thereto the ypiston I, made tubular and provided with the hollow stem I', which fits the smaller bore of the hub H', and has secured to its lower end the intercepting-valve disk I2, adapted to tit the seat II4 in the casing E and close the eX- The hub II is bored IOO haast-passage from the high-pressure cylinder. The piston I and its stem I are each provided with peripheral packing-grooves d c1, and the stem I has formed therein just 3 above the valve I2 a series of radial holesh b, (see Figs. S and 9,) through which any steam that enters the interior of the stem I will cscape into the chamber E, and pass thence to the receivers and the low-pressure steama chest when the valve I2 is closed upon its seat. The normal position of the intercepting-valvc I2 is raised or open, as shown in Fig. 8, which position is maintained bylive steam at boiler-1in'essure acting upon the annular 5 lower end o' the piston I, which steam direct from the boiler enters the annular space surrounding the stem I through the pipe d and the passagerl, east in the hub Il', as shown in Fig. S.

o The interior of the dome-like cap H2 is connected by the pipe c to the interior of the converting-mike casing J, above the valve J', as shown in Figs. l, 5, and 7. When the upward pressure ot the live steam ou the piston 5 I is overcome by the pressure ou the top of said piston I caused by the steam which has passed the converting-valve, the piston I descends and closes the intercepting-valve l2 upon its seat Il", but the steam above the o piston I cannot enter the receiver until the piston has descended far enough to withdraw the plug Il, formed in one piece with and pendent from the cap II2 from the central bore of said piston, when the steam enters 5 the chamber of the hollow piston and stem, and alteracting upon the increased area d ue to the bottom of said chamber to force the valve for the balance ol.' its movement with still greater force, escapes through the holes o l) l) into the chamber E. This delay ol' the steam in entering` the chamber E or receiver is inipo1tant,lor it otherwise might enter the high-pressure-exhaust passage before the intereepting-valve is closed and thus block the 5 high-pressure piston, which is just what the intercepting-valve is intended to prevent.

The object of requiring,r considerable steampressure on the top of the piston I before it will descend is to prevent steam entering the o receiver, except when it is wanted-that is,

when the high-pressure crank is in a disadvantageous position for starting. It the engine does not start promptly by the action of the steam entering the high-pressure cylin- 5 dcr, the steam will accumulate above the intercepting-valve piston, press down said valve till the steam can enter the receivers through the holes l) l) and start the engine by acting upon the low-pressure piston, or the engineer,

o by opening the throttle wide enough, can

make sure at will that the intereepting-valve will close and let steam into the receiver.

The areas for upward and downward pressures on the intercepting-valve can be so proi5 portioned with reference to each other that any desired result may be accomplished. The intercepting-valve can thus be made to always or occasionally act-that is, it may be made to act sensitively or sluggishly, as may be desired.

rl`he enlarged central portions of the receiver-pipes E5 and E are surrounded, or nearly so, with a series ot outwardly-projecting ribsff for the purpose of increasing the surface area of said receivers exposed to the hot gases in the smoke-box and thereby raising the temperature of the steam contained therein, and thus increasing the effectiveness of the low-pressure cylinder.

The intercepting-valve piston bearing is steam jacketed in order to prevent the hot gases in the smoke-box from having a destructive elect upon the oil with which the piston and valve-stem are lubricated.

The converting-valve casing J is secured by means of the liange J2 and suitable bolts or rivets tothe exterior of the smoke-box a little in advance ot the intercepting-valve casing, as shown in Figs. l and 2, and has formed in its lower end the valve-chamber g and in its upper end the cylindrical chamber 7L, the upper end of which is closed by the head J 3, and said casing is provided with an orifice t', into which the pipe e is screwed, and also withthe orifice i', which communicates through the pipe yj with the hi gh-pressu re exhaust-passage below the intercepting-valve I2, as shown in Fig. l. The lower side of the convertingvalve chamber is closed by the head J", having cast therewith the elbow-pipe J and the valve-scat 7.-., as shown in Figs. 5 and 6. The converting-valve J is secured to the lower end of the stem J, formed in one piece with or connected to the piston J7, fitted to and movable vertically in the chamber 7i and having formed in its periphery a series of annular packing-grooves ZZ and provided with the oblique pertorations m, as shown in Fig. 5. The orifice i opens into the chamber 7L about one-fifth (more or less) of thelength of said chamber from its upper end, and said chamber 71. has formed therein at that point the annular enlargement n, with which the lower ends of the oblique orifices m coincide when the converting-valve and the piston JT are in their raised positions. The portion of the chamber h that is above the enlargement lit serves as a dash-pot to cushion the pistou and prevent slammin When the convertingvalve is lifted by the pressure of steam beneath it, its upper surface comes in contact with the seat o, formed on the lower end of the bearing for the stem J, where it is maintained until the exhaust-steam from the highpressure cylinder, passing through the pipej and orilices i. and m to the upper side of the piston J 7, overcomes the upward pressure on said valve when it will be forced down upon the seat 7:. The converting-valve J is raised by the action of live steam, which passes from the steam-supply pipe D through the pipes p and J5, as shown in Figs. l and 2.

The casing J is provided with a vent-hole 0', which communicates with the interior of roo IIO

the chamber h, as shown in Fig. 2 and in dotted lines in Fig. 5, and said casing is also provided with a second vent-hole s, which communicates at its inner end with the interior of the bearing for the stem J6, as shown in Fig. 5.

The stem J6 has a portion of its length reduced in diameter, as at t, so that when the converting-valve is closed upon its seat k the steam that is in the chamber above the piston of the interceptingvalve will escape through the pipe e, chamber g, and vent-oriiice s to the atmosphere. When the highpressure cylinder makes its first exhaust, the converting-valve is depressed byaportion of the exhaust-steam passing to the upper side of the piston J7, as before described, which shuts olf the supply of live steam to the upper side of the intercepting-valve piston, and simultaneously opens the intercepting-valve supply pipe to the atmosphere, thus relieving theintercepting-valve piston of downward pressure, and enabling the boiler-pressure acting on the annular area of the lower end of said piston to raise and open the intercepting-valve. The size of the atmospheric comin unication can be so proportioned as to prevent the piston slamming in its upward movement, and the size of the pipe supplying live steam to the annular space below said piston can be such that the valve cannot slam in its downward motion, as it has io force this steam back into the boiler.

The escape of the steam into the atmosphere from the intercepting-valve-supply pipe becomes a tell-tale to the operator, and shows whether the valves are operating, and if steam escapes when the engine is running compound it shows that a leakage is occurring either in the converting or intercepting valve, or in both, from which one can always judge of the condition of those parts collectively, and thus easily locate the leakage in detail. As the intercepting valve is held open at all times when steam is up, whether the engine is working or not, it can be made to operate vertically, which has never heretofore been accomplished. rlhis adds much to its durability, as its weight does not wear the piston and stem. As the steam always keeps it up, it can never jar when the engine is running without steam or close and batter itself or close when the engine is reversed when running by the pumping of air or steam and air back into the receiver by the lowpressure cylinder. Any steam escapingfrom the vent-hole fr shows leakage of the piston J7.

The construction insures the opening of the converting-valve before the pressure of eX- haust -steam in the high pressure exhaustpassage accumulates above the receiver-pressure, and thus relieves the high-pressure piston of the early back-pressure. The intercepting-valve opens in advance of an accumulated back-pressure on the high-pressure cylinder to any desired degree. The covering of the holes b b in the lower end of the tubular stem of the intercepting-valve, as said stem and its valve rises, traps steam within the plunger, and thus prevents afinal slam. The opening of the throttle-valve causes steam to pass the under side of and lift the converting-valve and then pass to the upper side of the intercepting-valve piston.

In operating compound engines it may happen that when it is desired to start the engine the high-pressure crank is on one of its dead-centers, and steam acting upon the highpressure piston will not start the engine,l1n which case it becomes necessary to admitlive steam to the low-pressure engine, which, acting upon the low-pressure piston in the regular way, will tend to move it and start theengine; but, unfortunately, it is liable, unless prevented, to Iiow back through the receivers and high-pressure exhaust-passage to that side of the high-pressure piston that will retard or prevent its motion. Hence the necessity of using a valve in the high-pressure exhaust-passage to intercept and prevent such backward flow of the auxiliary steam. If the low-pressure crank should happen to be on one of its dead-centers, so that the engine must be started by the high-pressure piston, this back-pressure might, in the absence of an intercepting-valve, or in case the intercepting-valve was too slow in closing, block the high-pressure piston and prevent the engine starting, for the auxiliary supply of steam in nearly all compound engines using intercepting-valves enters the receivers and the low-pressure steam-chest whenever the throttle-valve is open. Now in order to prevent this auxiliary supply of steam from flowing back to the high-pressure piston itis necessary that the intercepting-valve should close in advance of the admission of the auxiliary supply of steam, thus permitting the high-pressure piston to move without resistance of back-pressure, whether said pistonis moved by the direct pressure of steam thereon or by power exerted thereon by its crank set in motion by movement of the low-pressure piston.

By the construction herein described and illustrated in the drawings this desirable end is accomplished.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

. l. In combination with the high and low pressure cylinders of a compound engine, their steam-chests and steam-passages, a forked pipe communicating with the exhaustpassage of the high-pressure cylinder at the end of its single portion and atits forked end to the low-pressure cylinder and provided near its connection to the high-pressure cylinder with a suitable annular valve-seat and an opening above said seat, a valve-supporting casing secured to said pipe and closing said opening, a hollow inner casing or hub bored out to two different diameters, ahollow piston and stem tted to the two bores of said hub, a valve secured to the lower end of IOO IIO

said stein in position to eo-operate with said seat tointereept the auxiliarysteani admitted to the receivers and prevent it passing' to the high-lnessure Cylinder, a pipe or passage for admitting,I live steam to the annular space 'below said piston to foree said piston and valve upward, a stationary piston or plug.;` fitted to the bore of' said hollow inl'ereepting-valve piston, and a pipe for admitting live steam to the chamber above said vz'ilve-piston, substantially as and for the purposes described.

The combination of the exhaust-pipe from the high-pressure cylinder provided with the valve-seat Hl, the easing' II, having the inner pendent hollow hub Il', the hollow eap Il?, provided with the pendent eylindrieal plug; H5, the hollow or tubular' piston I and stem I', the radial holes l l) in the lower end of the stein I', the pipe and passage d and d', Coin- 1n unieatin,r with the boiler direct, and a pipe or passage eoniieeting,` the interior of the steam-supply pipe with the ehalnber above the piston I.

3. The combination, with the high and low pressure cylinders of a compound engine, a pipe Connecting` the exhaust-passage of the high-pressure cylinder with the steam-chest of the low-pressure cylinder, and an intercepting-valve .in the exhaust-pipe, of the highpressure cylinder, a Converting-valve easing` provided with a valve-Chamber and a pistonearrying chamber, and an upper and lower valve-seat, a valve secured to the lower end of a valve-stein, a piston provided with an oblique perforation and attached to the upper end of said stein and movable vertically in the piston-Chamber, a live-steani-su pply pipe communicating with the under side of said valve, a pipe or passage connecting the valveehan1 ber above the valve with the ehaniber above the intereepting-valve piston, and a pipe or passage eonneetin gthe hi gli-p ressure exhaustpassage below the intereeptiiig-valve seat with the piston-Chamber oi the Converting-valve below the top of the piston when in its highest position, whereby the upper portion oi the piston-chamber is inade to serve as a dashpot, substantially as described.

+L. The Combination,with the high and low pressure o vlin ders of a compound e11p;ii1e,and a pipe connecting the exhaust-passage of the high-pressure Cylinder with the steam-Chest of the low-pressure eylindei-,ol' the intercepting-valve I2, its seat I l", the hollow stein I', and piston I, the steam-passage (Z d', the eonvert i iig-valve J', the valve-seats and o, the valvestern J, provided with the peripheral groove or reduction t, the easing J, provided with the vent-hole s, the pipe e, Connecting the eonverti iig-valve chamber with the Chamber above the intereepting'valve piston, a pipe for supplying.,r live steam to the under side of the eenvertingvalve, and a pipe connecting the highpressure exhaust-passage below the in tereeptnig-valve seat with. the interior of the ehamber containing the converting-valve piston.

5. The combination, with the high and low pressure Cylinders of a Compound engine, a pipe connecting' the exhaust-passage of the high-pressure cylinder with the steam-chest of the low-pressu re Cylinder, and an intercepting-valve in said pipe, of the Converting-valve easing' J, provided -with the ehainbers f/ and 71. and the seats ando, the piston JT, the steni J, the valve J', the pipe e, connecting.;` the eenverting-valve ehain ber with the chainber above the Aintereepting-valve piston, the pipe j, leading from the high-pressure exhaust-passage below the intereepting-valve to the chamber 7L, the pipe p, leading,` :from the steam-supply pipe to the under side of the eenvertingpvalve, and the vent-orifice fr, extending from the interior o[:` the chamber 71 to the open air.

In testimony whereof I have signed my naine to this specification, in the presence of two subscribing` witnesses, on this 27th day of May, A. I). 189].

FRANCIS W. DEAN. lVitnesses:

N. C. LOMBARD, 'WALTER E. LOMBARD.

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