USRE200E - Improvement in cut-off and working the valves of steam engines - Google Patents

Description

My ETERS; PHOTO-LITHOGRAPMEN, WASHINGTON. n c.

t 'UNITED STATES PATENT OFFICE.

GEORGE H. UORLISS, OFl PROVIDENCE, RHODE ISLAND.

IMPROVEMENT IN CUT-OFF AND WORKING THE VALVES 0F STEAM ENGlNES.

Specification forming part of Letters Patent No. 6,162 dated March l0, 1849;A Reissue No.. 200

. May 13, 1851.

To all whom it may concern 'Be it known that I, GEORGE. H.- CoRLIss, of the city and county of Providence, and'State of Rhode Island, have invented certain new and useful Improvements in Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description ofthe principle or character which distinguishes them from all other things before known, and of the manner of making, constructing, and using the same, reference being had to the accompanyin g drawings, making a part of this speciication, in which- Figure l is a side elevation of an engine on my improved plan; Fig. 2, a longitudinal vertical section; Fi g. 3, an elevation of the valves and the arrangement of parts working them; Fig. 4, a plan thereof; Fig. 5, a separate section representing a latch used in the valvegear; Figs, 6 and 7 a plan and section of an air-cylinder and piston for checking the motion of the valve apparatus.

The same letters indicate like the f1 gures.

In that class of steam-engines in which the steam and exhaust ports of the cylinder are opened and closed by slide-valves, whenever parts in all dated which consists in moving each of the steam and exhaust valves of an engine independently by means of one crank-wrist of a series, which are all attached toa common disk, wristplate, or other equivalent device, which is secured to and vmoved with a rock-shat't. The several wrists which work the different valves are arranged upon the wrist-plate i'n such positions, with respect to the rods and levers or valves, that they shall act like so many cranks, each of which vibrates near its dead-point or point of slowest throw, and therefore imparts but little movement to the valve it actuates with its fastest throw and therefore communicates the greatest movement to its valve when the latter is open. Two great advantages result from this method of working the valves In the first place, much of the power heretofore expended in moving the closed valve is saved; and,'secondly, the wire-drawing of the. steam lis reduced, because the valves while opening and closing the ports are moved with increased speed.

the method of regulating the cut-off of the the valves close the ports the steam presses them upon their seats with its whole force, and they cannot then be moved without the expenditurey of a considerable amount of power, but when the valves do not completely close their ports the steam pressing upon both sides of them does not tend to hold them upon their seats, and at these times the valves can be moved with but a small exertion of force. When a valve has closed its port its office is performed, and hence the force exerted in any further movement of it while the port remains closed is wholly lost. Now, it is customary in this class of engines to connect the valves rigidly, so that when one is moved the other is forced to move with it to the same extent. The closed valve is therefore moved with the openin g one, and consequently the whole amount of force consumed in moving it while closed is expended to no good purpose, and

tends only to increase the wear and tear of the engine. To avoid this sacrice of power and at the same time to retainthe advantages which result from the connection of the valves is the object of the firstpart of my invention,

steam in its passage into the engine, and it consists in effecting this by means of the governor, which operates cams so that when the velocity of the engine is too great these cams shall be moved by the action of the regulator to such positions that catches on the valverods may the sooner come in contact with them to liberate the valves and admit of their being closed by the force of weights or springs, and thus'cut oli' the steam in proportion to the Y velocity of the engine, this being done sooner when the velocity of the engine is to be reduced, and later when it is to be increased.l

In the steam-engine represented in the ac- Y companying drawings the steam and exhaust Y tached to one extremity of a valve-rod, p, which is fitted at its opposite extremity with a sliding head, g, that is linked, by a connecting-rod, r, to one arm, 3 of abell-crank, t. The 4other arm, o, of the bell-crank is connected by other devices which connect them with the when the latter is closed, while each moves- The second part of my invention relates to l a rod with a wristpin, fw, on the wrist-plate x. The latter is secured to a rock-shaft, to which the requisite vibratory motion is imparted by an eccentric, a', through the intervention of an eccentric-rod and an arm, y, secured to the rock-shaft. The wrists w of the two valves are in this example a quarter of a circle distant from each other, and the two connecting-rods extend in opposite directions from the rock-shaft. Hence, when one wrist is at its point of greatest throw, the other is at its dead-point, and when one is imparting toits rod and the valve connected therewith the greatest movement, the other is imparting to its valve the' least. Each valve is therefore moved alternately fast and slow, and the fast movement of one is effected during the slow movement of the other, nearly the whole movement or throw of each valve vbeing eii'ected while the port isv either partially or wholly open, at which time the least power is required f to move it; while as the small remnant ofthe throw when the port is closed is effected during the slow movement, but little power is then required, as the distance to which the valve is moved is now very short.

The steam-valves l Z arelworked in a manner similar to that of the exhaust-valves, with the exception of an arrangement by means of which they are made to close and cut oft' the supply of steam at any required portion of the stroke. The valve-rods b of thesevalves are double, and, instead of being permanently linked to their appropriate bell-cranks, are each connected by a detachable link, la', with a rack, g', whose teeth engage with those of a toothed sector, f', on the bell-crank. This detachable link h is hinged at one extremity to the cross-head c', which unites the two members ofthe double-valve rod. Ithas a shoulder, i', at its-opposite extremity, which engages in a corresponding socket on the rack, and is kept in plaee by a spring, f. This link h is also fitted near the rack with a projection, j which is struck at the proper moment to detach the link from the rack by a revolving helical cam, k. The helical cams which detach the links 7i h of the two steam-valves l l are both secured to .an upright shaft, I/,which is caused to revolve by the movement of vthe crank-shaft, and is arranged at the same time to move freely up or down in its boxes. This shaft is connected at r with the governor, which, in the present instance, is of the centrifugal variety, that being the kind I have used, deeming it the best, so that it shall move up or down as the balls of the governor rise and fall. When the governor-balls s s are at their lowest position, the shaft l is depressed so far that the helical cams It k are below the range of the valve-links hf h', and, consequently, cannot detach them; hence, in this position of the governor balls, the steamvalves, being connected with their wrist-pins throughout the whole length of the stroke, are opened and closed in the same manner as the exhaust-valves. As, however, the velocity of the engineis increased and the governor-balls rise under the. increased centrifugalv force, the upright shaft l is correspondingly raised and the cams, being now revolved within the range of the valve-links, strike the projections j and detach the links h from their racks. The helical cams extend around the shaft in the same direction as the latter is turned; consequently, the higher the shaft Z and its cams are raised the sooner will the cams strike the projections and detach the links. As soon as the links are detached, the valves, being entirely disconnected from the mechanism by means of which they are opened, are, consequently, free to close. As the steam-valves in the steam-engine represented move horizontally, they do not tend to close by their own'v weight, and are, consequently, closed by means of weights'o o', which act through the intervention of bent levers or bell-cranks m 1 v upon cross-blocks n', secured to the respective valve-rods.

In order to prevent the jar which would result from the sudden stoppage of the motion of the weight, each cross-block a has a cylindrical socket formed in the face nearer the steam-cylinder, and a piston, p', is secured to the engine-frame, which enters the cylindrical socket and compresses the air within it to form an 'elastic cushion to prevent the jar. As the racks g' are moved back by the action of the wrist-pins and the bell-cranks, the shoulder of the link re-engages with the socket on the rack, so that the valve, being now reconnected with the valve mechanism, is opened by the wrist-pin at the proper moment to admit steam into the cylinder. When the steamvalves are not used as variable cut-ott' valves, they are to be operated in every particular like the exhaust-valves. It is obvious from the foregoing description that when the valves are so arranged that they move parallel with the axis ofthe cylinder, as is thel customary arrangement in slide-valve engines, the rockshai't by which they are operated may with advantage be located in a position. different from that described above, and the valve-connections must be adapted to this change.

A convenient mode of arranging the several parts when the valves move parallel with the Slide ofthe governor by levers mayr be made] f to slide in the direction of the plane of motion of the valve-rods to vary the periods of liberating the catches of the valve-rods, or wedgeformed. stops or cams may be substituted for the helical cams and attached to the cam-rod, which in that case must not turn.

The mode of applying the principle Which I have first described is the one which I have essayed with success, and therefore I have described it minutely7 but the two modifications indicated will show clearly that the same principle is susceptible of various modifications.

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

1. The method, substantially as described, of operating the slide-valves of steam-engines by connecting the valves that govern the ports at opposite ends of the cylinder with separate arms of the rock-shaft, or the mechanical equivalents thereof, so that from the motion thereof the valve that keeps its port or ports closed shall move overa less space While its port 01' ports are closed than the one that is opening or closing its port or ports, and vice versa,

while at the same time the two arms by which they are operated have the same range of motion, as described, whereby I am enabled to save much of the power heretofore required to Work the slide-valves of steam-engines, and

by which, also, I am enabled to give a greater range of motion to the valves at the periods of opening and closing the ports7 to facilitate the induction and eduction of steam, as speciscribed.

GEORGE H. GORLISS. In presence of` J oHN H. CLARK, E. J. NIGI-ITINGALE.

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