US514024A - Valve-gear for steam-engines - Google Patents

Description

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' A. NICHOLSON.

VALVE GEAR POB. STEAM ENGINES.

No. .514,024.- `'IaJzented Feb. 6, 1894.

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UNITED STATES PATENT ENCE.

AARON NICHOLSON, OF ALBANY, NE\V YORK.

VALVE-GEAR FOR STEAM-ENGINES.

SPECIFICATION forming partof Letters Patent No. 514,024, dated February 6, 1894.

Application filed December 14,1892. SerialNo-455,l36. (No model.) I

To a/ZZ whom t may concern:

Be it known that I, AARON NICHOLSON, of the city and county of Albany, in the State of New York, have invented new and useful Improvements in Steam-Engines, of which the following is a specification.

My invention relates to improvements in valve-gear for steam engines, but especially to steam engines of the Corliss type provided with disengagin g steam -valves which are utilized for cutting-O the steam so as to have it operate expansively; in the usual form of valve-motion used on the Corliss type of engmes the disengagement of the steam-valves 1s effected while said valves are making their openlng movement, and, for that reason, the disengagement occurs when the engine is at half-stroke, or before ithas attained the halfstroke point.

The object of my invention is to provide facilities for increasing the range of expans1on in the Corliss type of engines,'and to automatically vary the point of cutting-off to correspond to the duty that the engine is requlred to perform. This object I attain by the means illustrated in the accompanying drawings, which are herein referred to and form part of this specification.

In said drawings, Figure l is a side elevation of the parts of the steam engine affected yby my invention, some of the parts being removed to show underlying parts. Fig. 2 is an end elevation of the same with a part of the rim of the governor-wheel broken out to show parts of the governor; and Fig. 3 isa detached side elevationl of the cylinder and valve-connections.

As represented in the drawings, A designates the cylinder of the steam engine, which is of the ordinary Oorliss type and provided with the usual oscillating form of valves used in that type of engine. Of said valves, the two steam-Valves, 1, are arranged to operate independently of each other by being tripped from their operating mechanism. The two exhaust-valves, 2, are preferably connected together by a yoke, 3, so as to be moved simultaneously. Each of said steam valves has a bell-crank,4, secured to its stem which projects through a stuffing-box, 5, and to the horizont-al arm of said bell-crank a rod, 6, is jointed, said rod being connected to the plunger of a dash-pot, '7, which is provided for the purpose of governing the closing movement of said valve. To the other arm of each bell-crank there is pivoted a toe, S, which is normally depressed by means of a spring, 9, to hold the free end of said toe in a required position. The yoke 3 is provided with a slotted opening, 10, for the purpose of allowing said yoke to travel in a curved -path to accord to the arc prescribed by the wrist-pins, Il, in the arms, 12, secured to the outer end of each exhaust-valve 2. When preferred a rod jointed in its middle to connect to a wrist-pin moving in a direct line may be substituted for the slotted yoke.

B designates the main eccentric by which the opening movement of the steam-valves and the opening and closing movements of the exhaust-valves are effected; said eccentric is secured to the engine-shaft 13 in a position to give a required lead to theopening movements of the stearnand exhaust-valves, and it is connected-by an eccentric-rod, 14- to a tripper-slide, C, which is fitted to move in a guide, 15, on the side of the cylinder A; said tripper-slide is provided with a pair of trippers, I6, which are pivoted, as at 17, to said slide so that the engaging end of the two trippers will be faced in opposite directions; the opposite end of each tripper is beveled or rounded, as at 18, and is provided with a stud, 19, against which a spring, 20, takes to normally retain that end of the tripper in a depressed position.

D designates a governor, of which I do not claim to be the inventor, which is secured to the engine-shaft 13; said governor consists of a pair of weighted-arms, 2l, pivoted to the governor and connected to springs, 22, which normally retain said arms in their closest po- ICO ends of the trippers 16 and eect a tilting movement of the latter on the pivots 17. A face-plate, 27, is secured to the tri pper-slide O and is provided with slottedopenings, 28, through which the studs 19 are moved. The springs 2O are preferably secured to said faceplate adjacently to said slotted-openings, and a pendent arm, 29, attached to the tripperslide C, is provided with a wrist-pin, 30, which engages in the slotted-opening, l0, of the yoke 7 for the purpose of imparting a reciprocating motion to said yoke.

My invention operates in the following manner: Premising that the engine is started in motion with the wighted-arms 21 in the position shown in Fig. 1, so that the cam-plate G will not eect a disengagement of the tripper 16 from the toe 8 with which it is engaged at the time, for the reason that the two eccentrics are then in substantially the same position in respect to the throw of said eccentrics; as the engine increases its speed said weighted-arms will be moved, by centrifugal force, to swing farther from the shaft 13,and thereby the sleeve E will be partially rotated to advance the throw of the eccentric F in respect to the throw of the the eccentric B, and, as a consequence, the cam-face 2G nearest the open steam-valve, will be quickly carried into Contact with the rounded end of the corresponding tripper 1G and effect a tilting movement of the latter that will disengage said tripper from the toe 8 and allow the weight of the rod 6 and its appendages to effect the closing movement of said steam-valve; the variation in the point of cutting off the steam being dependent upon the position in which the eccentric is automatically set by the action of the governor D.

I am aware that steam-engines have heretofore been constructed with independently operating steam and exhaust valves, but the tripping-mechanism for releasing the steamvalves was substantially different from mine and operated in a dierent manner; and I am also aware that Patent No. 329,288 shows a steam-engine having two detachable valves which govern both the admission of steam and the exhaust of the same, so that the eX- haust-ports will be closed simultaneously with the closing of the steam-ports to effect the cutting-off of the steam, thereby producing an objectionable degree of compression of steam, which will detract from the power of the engine. I do not claim either of said constructions; but

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

In a steam engine, the combination with a tripper-slide, O, having a pair of tilting trippers, 16, pivoted thereto and arranged to take against arms, 4, secured to the oscillating steam-valves; said tripper-slide being connected--by a yoke 3-to the arms 12 secured to the oscillating exhaust-valves, of a sliding cam-plate, G, tted to reciprocate in the tripper-slide and provided with cam-faces, 26, arranged to tilt said trippers, as and for the purpose specified.

AARON NICHOLSON.

lVitnesses:

WM. II. Low, S.- B. BREWER.

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