US425219A - Island - Google Patents

Description

(No Model.) 0

N. T. GREENE.

EXHAUST VALVE GEAR POR- ENGINES.

No. 425,219. Patented Apr. 8, 1890.

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| a Hr m ill uv l WITNESSES.

UNITED STATES PATENT OFFICE.

NOBLE T. GREENE, OF PROVIDENCE, RI-IODE ISLAND.

EXHAUST-VALVE GEAR FOR ENGINES.

SPECIFIGATIONforming part of Letters Patent No. 425,219, dated April 8, 1890.

Application filed December 10, 1889- Serial No. 333,247. (No model.)

To aZZ whom it may concern:

Be it known that I, NOBLE T. GREENE, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Exhaust-Valve Gear for Steam-Engines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

My invention has relation to the valve-opcrating mechanism of automatic cut-off engines having slide-valves; and it consists, essentially, of a steam-engine having the cylinder thereof provided with two suitablymounted governor-controlled inlet-valves, in combination with two exhaust-valves reciprocating transversely of the cylinder by means of a rocker-shaft actuated by gears vibrating by and in unison with the main eccentric.

The object of my invention is to simplify and eheapen the construction of the exhaust' valve mechanism of steam-engines having slide-valves. By means of my improvement the relation of the exhaust-valves to the steam-valves as to opening and closing can be readily changed when. desired. I employ but one eccentric to actuate the four slidevalves. The eccentric-rod connects with a loosely-mounted rocker-lever carrying at its upper end a link which is jointed to the sliding bar, the latter carrying spring-tappets adapted to intermittingly engage levers that operate the steam-valves. To the lower end of the rocker-lever is secured a bevel-toothed wheel, which meshes into a similar wheel adjustably secured to a horizontal rocker-shaft carrying arms or levers which reciprocate the exhaust-valves transversely of the cylinder, the invention being an improvement on the exhaust mechanism shown and described in United States Patent No. 12,507, granted to me March 13, 1855.

In the accompanying drawings, Figure 1 is a side elevation of a steam-engine in partial section, viewed from the back, as provided with my device for operating the exhaustvalves. Fig. 2 is a transverse sectional view, taken on line :0 cc of Fig. 1, through the back exhaust-ports, 850. Fig. 3 is a partial side elevation showing a slight change in the manner of mounting the rocker-shaft and valve connections, and Fig. at is a cross-sectional view taken on line 0 0 of Fig. 3.

In the drawings, Ct indicates the steam-cylinder of a steam-engine; b, the bed piece or frame; p, the pillow-block or main bearing; 3, the main shaft, and e the eccentric mounted thereon.

i designates the rocker-lever, loosely mounted on the stud is, secured to the frame, as common. A bevel-wheel or miter-gear w is secured to the axis of the levert' and vibrates back and forth in unison with the lever, motion being transmitted to the latter by means of the eccentric-rod e, jointed thereto. A shaft 0, which I term a rocker-shaft, extends parallel with the cylinder and is supported in bearings 25 75 The forward end of this shaft is provided with a miter-gear w, adjustably secured thereto by a setscrew This gear intergears with and receives motion from the other gear-wheel 10, before described. In this arrangement the exhaust-valves m are provided with a series of short narrow ports and travel crosswise of the cylinder. Each valve-stem extends through the back bonnet or cover d and is secured to a cross-head d, fitted to travel in guides formed in the cover. An arm or lever Z is secured to the shaft a contiguous to each valve, motion being trans-- mitted to the valve by means of a link Z jointed to the cross-head and lever.

From the foregoing it is obvious that the angular movement of the rocker-lever Will be suflicient to reciprocate the narrow-ported exhaust-valves back and forth past the cylinder-ports 0, as in opening and closing.

In the arrangement shown in Figs 3 and 4 the relative position of the levers Z to the links Z is such that the maximum travel of the valves is attained by a given angular movement of the lever 1', whereas in Figs. 1 and 2 the location of the rocker-shaft is such that the angular movement produces a minimum travel of the valves. It is to be understood that the two valves m are arranged or set in relation to each other as usual, the corresponding levers Z, 850., being adjusted so as to open and close the valves alternately by means of the gear-driven rocker-shaft c.

The steam-valves and mechanism for operating them are well known, and consequently need not be described in detail. I would state, however, that a mounted slide-bar u is made to travel to and fro parallel with the axis of the engine by means of a connecting rod or link 6 jointed both to the bar and rocker-lever The bar it carries two reversely-arranged tappets 16 which in traveling engage hooks or latches f, mounted at the lower ends of the valve-levers g, which latter are secured to the ends of the valvestems f, all as common. The steam-valves a travel longitudinally of the cylinder, the reciprocating movement of the bar to producing an engagement of the tappets with the levers g and causes the valves to open, thereby admitting steam alternately to the ends of the cylinder. The valves close after being released by means of weights or vacuum-pots '0 jointed to the valve-levers.

The relative height or position of the tappets, and consequently the amount of surface in contact with the valve-levers for any stroke, is determined by a lever t", actuated by a governor, all substantially as usual to automatic cut-off steanrengines.

The upper end of the rocker-lever L' is provided with a handle 1', by meams of which the engineer is enabled to operate all the valves simultaneously after first unhookin'g the eccentric-rod a. By also unhooking the slide-bar connection 6 the exhaust valves only will be operated upon vibrating the rocker-lever back and forth.

In use steam passes from the steam-chest through the uncovered steam-port into the cylinder. The steam, acting upon the piston, forces the latter ahead and by means of the usual rods, &c., causes the shaft to revolve. At the proper time, as determined by the governor, the tappet is released from the steamlever, the weight instantly closing the valve, thus cutting off live steam from the cylinder. The correspondingexhaust-valve iskept closed meanwhile, (the forward one being open.) As the piston reaches the end of its stroke the continued action of the eccentric .closes the lastnamed exhaustvalve and gradually opens the other one. The expanded steam then passes from the cylinder, through the exhaust-ports o and valve, into the exhaustchest 0 and finally enters the escape-pipe 0.

Obviously the ratio of the gears w may be changed without departing from the spirit of the invention-that is to say, the gear mount ed on the axis of the rocker-lever i may be somewhat larger than the fellow gear secured to the shaft 0. This arrangement would give to the valve-operating shaft 0 a greater angular movement, thereby opening the exhaustvalves quicker and permitting of an increased lap, if desired.

I do not claim, broadly, as my invention a steam-engine having its four valves actuated by a single eccentric; but

Vhat I do claim is In an automatic cut-off steam-engine, the combination, with governor-controlled steamvalvcs moving longitudinally of the steamcylinder, of two exhaust-valves reciprocating transversely of the cylinder by mechanism consisting of an eccentric-driven rocker-lever, a pair of bevel-gears actuated by and in unison with said rocker-lever, a mounted rockershaft having one of the bevel-gears secured thereto, levers or arms adj ustably secured to the shaft, and links or other analogous connections jointed to the levers and connected with the exhaust-valves, substantially as hereinbefore described.

In testimony whereof I have aifixed my nature in presence of two witnesses.

NOBLE T. GREENE.

YVitnesses:

CHARLES HANNIGAN, GEO. II. Rnnnvc'ron.

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