US33477A - Improved cut-off for oscillating engines - Google Patents

Description

x Miren STATES Fries.

PATENT XVILLIAM CRAIG, OF BINGHAMTON, NEV YORK.

Speciiication forming part of Letters Patent No. 33,477, dated October 15, 1861.

To @ZZ whom it may concern:

Be itknown that I, WILLIAM CRAIG-,ot Bing-1 hamton, inthe county'of Broome and State of New York, have invented a new and 4Improved Variable Cut-OEE forOscillating Steam- Engines; and I do hereby declare that the following is af ull, clear, and exact description of the same, reference being had tothe accompan ying drawin gs7 forming part of this speci tication, in Which- Figure 1 is a side view of an engine with the steam-pipe and steam-chest cover removed to expose the slide-valve and cut-off. Fig. 2 isa horizontal section of the same. Fig. 3 is a side view ofthe cylinder, exhibiting the t'ace of the valve seat. Fig. 4 is afaee view of the g valve. Fig. 5 is a back view of the same. Fig.

6 is a side view of the main-valve gear.

Similar letters of reference indicate corresponding parts in the several figures.

This invention consists in a ent-o valve applied and operated, substantially as llereinafter described, in combination with an oscillating induction and eduction valve 'Work- .ing against a seat at the end of one of the trunnions 1n such a mannerV as to cause the.

steam to be cut oii' at various points, as may be desired, in the earlier portion ofthe stroke of the engine.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

A is the cylinder, having hollow trunnions B B', through the former of which the induel tion of steam to the cylinder is effected and through the latter the eduction from the cylinder. In the back of the trunnion B is the iiat seat a ct for the main valve C, by Which the induction and eduetion of 'steam are effected, said valve being furnished with a stem D, which protrudes through a stuffing-box h in'an elbow formed in the stationary steampipe J. The end of the trunnion B is closed, to make it constitute a steam-chest, bya capplate I, which has a central socket j, which is fittedinto the stationary pipe J with a stuffing-box joint c c, and which is furnished with a crank-arm E, Whose Wrist-pin bis connected by a rod F with a shorter crank G or an eccentric on the crank-shaft H, said crank-arm and crank or eccentric being so arranged as to give the valve C an oscillating movement independently ot' the cylinder in a direction which is always the reverse of thatof the valve-seat a, which oscillates with the cylinder. y

The operation of the valve in combination with the seat in the trunnion thus produced is the same aus that of the valve which constitutes the subject of Letters Patentgranted to me bearing date September l2, 1854; but the valve and seat differ slightly in the arrangement of 'their steam and exhaust ports, and the valve dii-fers in having a stem instead of being connected toa portion of the steampipe, the latter point of difference being necessary to provide a seat 7c on the back of the valve for the application of the cut-ott valve.

The arrangement of the ports in the valveseat a a and valve C is best illustratedin Figs. 3, 4, and.

s s are the steam-ports in the seat, and e the exhaust-port, ot' radial or sector form, the latter communicating by a halt-band with the trunnion B, to which the exhaust-pipe is to be connected, the steam-ports being directly opposite each other andthe'A exhaust -port midway between them.

d is a cavity, ot corresponding area with the exhaust-port, arranged directly opposite,

but having no outlet, it-s object being merely l to equalize the surface of the seat on opposite sides ot' the center.

i i are the induction-ports ot' the valve, passing completely through it, and e the eduction-port, consisting ot' a cavity similar tothat in my patented valve and in a common slide-valve, but having a bridgefacross it corresponding with the spaceg between the induction-ports. These ports t' c are sectorshaped like the ports in the seat.. The said ports t' i e', space g, and bridge f may be arranged and proportioned to give the valve lap and lead, to operate on the same principleasacommon reciprocating lap slide-valve.

The induction-ports z' t' are narrowed but elongated radially from the face toward the back or cut-off seat k, so that they present the sa me area throughout, but have such form in the seat k as is best adapted for the application of the cut-off. v t

K is the cut-off valve, consisting of a plate fitted to turn easily on the valve-stem D and faced to iit the seat k on the back of the main valve and having two radial or sector-shaped wings, each large enough to cover one of the induction-ports i z' of the main valve, but so arranged relativelyto each other lthat when one port t' is covered the other is Wide open, as shown in Fig. l. This cut-off is held to its seat k k by the pressure of the steam on the back of it; but I have represented alight spring m applied round the stem D to keep it there when the steam is shut off from the engine. a'

ZZ are two projections on the back of the cut-off valve, one on each wing, and m is an arc-formed plate or bar of metal arranged within the trunnion B and attached to a stem n, which is arranged radially to the trunnion and Works through a stuffing-box o in the same. The ends ot this arc-formed piece m occupy such positions as to form stops against which the cut-off valve in oscillating about the axis of the valve-stem may bring its projections in contact. The stem n has at its upper or outer extremity an arcformed slotted cross-head p, which is connect' ed by a pin q, working in the said slot, with a rod r, which is itted into a stand M, in which it is capable of being moved or adjusted longitudinally, such adjustment causing the are piece m to be brought nearer to or farther from the center of the trunnion, and the arcformed slotted cross-head p permitting the oscillation of the cylinder. As the main valve C is moved by the action of the crank or eccentric G on the crank-arm E on its stem the cut-oit valve is caused to move with it bythe frictionproduced between them by the pressure of steam on thecut-otf valve so long as the projections ZZ are free of the arc piece m; butwhen in the oscillation ot' the cylinder and main valve the'arc piece and either of the projections are brought in Contact the continued movement of the cylinderand main valve causes the cutoff Valve to move in the opposite direction to themain valve and toclose one or other ot theports ii, according to 'the direction ot' the oscillation, and thus to cut ott the steam from the main valve. rlhe closing of the ports z L takes place sooner or later in the stroke of the engine between the commencement and half-stroke, according as the arc piece m is nearer to or farther from the center of the trunnion, and in order to adjust the said arc piece to cut oft 'permanently at such point as may be desired the rod a" may be operated by a screw s and nut t, or by'any equivalent means; or, if it be desired to employ the cut-oft as a means of regulating the speed of the engine under a Varying load or steam-pressure, the said rod may be connected with a governor in such a manner as to cause the are piece m to be moved toward the center of the trunnion as there is any tendency to increased speed, and vice versa.

To relieve the main valve ot' unnecessary pressure, I connect the outer end ot' its stem by a lever u with the rod u oi". a piston fitted to an independent steam-cylinder w, one end of which is open tothe atmosphere and the other end closed. Steam admitted to the closed end of the cylinder presses against the piston, 'which is properly proportioned for the steam vacting on it to balance as nearly as is practicable the pressure on the valve. The cylinder w may be placed in line with the valve-stein,\vl1ich will then have a direct connection with the pistonfrod 1i.

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

The cut-off K, applied to oseillate yon the stem of and in contaetwit-h the back of an independenily-oscillating slide-valve Within one of the trunnions of an oscillating steamengine, in combination with the adjustable arc piece or double stop m, also applied within the trunnion, but movable or adjustable under the.,control ot' a governor or other device on the exterior' thereof, the whole operating substantially as herein set forth.

Y 'Y WILLIAM CRAIG..`

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