US8253A - Island - Google Patents

Description

. gear.

UNTEi srArEs PATENT Ormea;

" GEORGE H. coRnIss, or PROVIDENCE, RHODE IsnAND.

Specificaticn formingpart of Letters Patent No. 8,253, dated July `29, 1 851; Reissued July 26,` i 185e, Nq. 7801 i To all whom it may concern Be it known that I, GEORGEH. CoRLIss,

Steam and Gas Engines; and,l doihereby declare that the following is afull, clear,` and exact description of thesame, reference being had to the accompanying drawings, which form part `of this specification and'in which- Figure l represents a side elevation of a beam engine with my valve-gear applied thereto; Figs. 2- and 3 are fragmentary side elevations of the steam cylinder and valve-1 gear; `andligl 4 is asection of one of the valvechests andthe parts adjacent thereto.`

My improvement hasreference to `that class of cut-off valve motions in which the connection betweenthe valve and the eccentric or the equivalent thereof, which opens the valve, is broken to allow` the valve to move independently of the eccentric and close its steam portbefore the piston has ccmpleted itsmstroke; and my Iimprovement consists in eifectingfthis disconnection of the valve and the eccentric gear, or the equivalent thereof,jby `imparting to the lift-4 ing roda lateral movement whichislimited and Icontrolled by `an` adjustable stop and spring; so that the lifting rodnot only `performsthe duty usually imposed uponit of opening the valve but also performs the ofi'ice of a catch or` latch in connecting and disconnecting the valve withtheeccentric In the accomp nying drawings A is the steam cylinderandB the crankshaft of the engine. The steam cylinder isfitted with two side pipes C, D, which form the" valve chests in which the valves are contained. That side pipe C farther from the crank shaft B, contains the steam valves 4and is connected with the steam pipe which con- Veys the steam from the boiler; theother side pipe containsthe exhaust valves and is connected with the exhaust pipe through whichpthe exhaust steam from the cylinder is discharged. `The steamu and exhaust valves are in this instance of the `slidevai riety, each ismoved to o pen and close its-respective portsby an arm y which pro-j` jects from a short rock shaft e.' These rock Shafts'fefend transversely thrash Stufrig boxes in the sides` of their, respect-ive valve chests and their projecting extremities j are i fitted a a, b The arms a, a, of the exhaust valves are connected means of lifting rods b, bij, with separatecrank wrists c c secured to a diskplate E to which a rocking motien imparted by the eccentric F through the interventien of theeccentricfrod d, and a crank f, securedvto the diskplate The connection of these exhaust valves with the crank `wrists of the disk plate and thence with the eccentric are permanent, and hence the exhaust valves` will be alternately opened `and Aclosed with a regular movement, the epening ofone exhaust valve "being simultaneous `with, the

closing of the other. i

The armsgmgofthe steam valve rechi shafts terminatein toes' o, o, and areoperu ated by lifting rods it, it, which are pivoted to suitable crank wrists e e uponthe disk plate These lifting rods terminate in hooks z' z', which engage with the toes o 0 j of the rockshaftarms, and are keptengaged with them by springs "j j which bear upon the backs ofthe lifting rods; hence fas long as these hooks continue enga-ged `with the toes of the rock shaft arms the "steam valves close andthuscut off` the passage ofr steam to ,t

the steam cylinder.` In order to elfectthis disengagement of the lifting 'rods "which comniunicate` the l movement of the eccentric to the steam .valves,` each `rod"is littedilwith an adjustable stop 7c, le, against whichthe face of the rod bears in moving, and which j can be moved to` cause the hooked extremity of therod to detach itself from the respective toe ofthe rock shaft arm when the steam piston has accomplished any required portion of its stroke. These stops are constructed to slide in blocks m, m, secured to the framework or other convenient portion of the engineg'their extremities bear against two inclined blocks Z Z which are secured to a rod G, by raising or lowering which the stops are moved to effect the disengagement of the lifting rods when the piston has accomplished a less or greater portion of its stroke. This sliding rod G in the examples represented in the drawing is constructed to be moved by hand through the intervention of a rack n and worm 29,' the last of which is turned by hand to screw up or screw down the sliding rod; but the sliding rod Gr may he moved by the engine itself, by connecting it with the slide of the gover nor so that as the latter is moved the point at which the cut-off is effected will be varied.

The inclined blocks, Z, Z, are of such form that when they are raised to their highest positions, as at Fig. 3, the stops 7c 7c, will be so far projected that the lifting rods, 7L, h, bearing upon them, will in moving disengage from the toes of the rock shaft arms before the valves have moved sufliciently to open their respective ports; while if the inclined blocks are depressed by the rod Gr to their lowest positions, as at Fig. 1, the stops, 7c, lo, will recede in their slide blocks, m m, sufficiently to have no action upon their respective lifting rods, and hence the latter will continue engaged with their respective toes throughout the whole extent of the stroke. If the inclined blocks be set between these two extreme positions, as at Fig. 2, the stops will be more or less projected, to detach the lifting rods sooner or later, as may be required to regulate the amount of steam admitted to the steam cylinder.

In order to effect the closing of the steam valves after they are disconnected from the eccentric gear, the rock shaft arms appertaining to each of them, has a weight r suspended from it by a rod s. These weights are sufficiently heavy to effect the instantaneous closing of the valve whenever its ap* propriate lifting rod is disengaged from the toe of the rock shaft arm. In order to prevent the slam and jar that would result from the sudden closing of t-he valves, these weights are fitted to move easily in appropriate sockets formed, in the present example, in the bed ,plate of the engine. The weights moving in the sockets act as pistons to compress the air therein and thus retard their descent, and as air cushions to prevent the slam or jar. If the compression of the air was continued throughout the whole descent` of the weight 'its motion would be too much .retarded to enablev it to close the valvewith the requisitel speed; an orifice, t, Fig. l, 1s therefore made 1n each socket near its lower extremity to permit the free entrance and thus cuts ofi' the escape of the air re-v maining in the socket just before the valve closes its port, when the air, caught, or shut up in the socket, being compressed, will retard the further movement of the weight and will act as an air cushion to prevent the slam or jar.

When the stops are acting, the lifting rods are alternately disengaged in their inward movement toward the center of the disk plate, to allow the valves to close under the action of, their respective weights, as each lifting rod is moved outward, its extremity being pressed by its appropriate spring y' against the toe of its respective rock shaft arm is caused to rengage therewith in time to open the valve at the returning rock of the disk plate in order to insure the closing of each steam valve before it is reopened a curved snug 'v is projected from the face of each lifting rod L, which in the outward movement of the latter would strike against the lower side of the toe of the rock shaft arm and thus close the latter if by any accident it was not previously closed by its appropriate weight.

In order to lessen the wear of the toes and the hooks of the valve gear, their rubbing faces are faced with hardened plates of steel which when worn can be readily replaced.

The arrangement of the lifting rods and the method of operating them by the disk plate, as represented in the' accompanying drawings, is peculiarly suited to this method of effecting the disengagement of the valves from the mechanism by which they are opened, for the disk plate imparts a transverse motion to t-he connecting rods, which causes them to rock upon the stops and thus slide off their respective toes on the rock shaft arms. But while I prefer this ar# rangement of eccentric gear I wish it to be understood that I do not restrict myself to its employment as my improvement may be ap'- plied to many othery systems of mechanism by which valves are opened; as such systems may not possess the peculiar rocking mot-ion I have mentioned, it will be necessary in some cases to disengage the lifting rods by a positive movement which may at the proper moment be imparted to the lifting rods by some moving member of the engine through the intervention of any convenient and suitable mechanical device.

I claim- In combination with the reciprocating motions communicated to the lifting rods by the eccentric gear, I claim impartinga lateral movement to the free extremities o-f said lifting rods to disconnect them from .the

valves and permit the latter to close to cut off the steam or other expansive uid by `same more durable and less liable toget out 10 Which theengine may be driven, iwhereby `of order. n n

these rods are made to perform theirusual In testimony whereof I have `hereunto duty ofjopening the valves and in addition subscribed my name. that of catches or latches in alternately con- GEORGE CORLISS n neeting the valves `with and disconnecting n them from the mechanism by Which they are Wvitnesses:

` opened, thus greatly simplifying the con- THOMAS A. GENERE, i

struction of the valve gear rendering the WM, 11 I-IENDERSOl`Tl i i i [FIRST PRINTED 1913.] i

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