US75034A - To all to - Google Patents

Description

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HENRY oQLofrHnoP., or MILFORD, MASSACHUSETTS.

LettersV Patent No. 75,034,"datedllfarch 3, 1868,

IMPROVEMENT Iil STEAM-ENGINE GvUT-OFFS.

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Be it known that I, HENRY O. LOTHROP, of Milford, in thc county of Worcester, and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Steam-Engines, or in the inode of operating the cut-olf of the-same; and do hereby declare the following to be a full, clear, and exact description thereof, due reference being had to the accompanying drawings, making part of this specification, and in which- Figure 1 is a vertical and longitudinal section, and

Figure 2 a vertical and transverse section ofthe cylinder, steam-chest, and valvo of a steam-engine with my invention or improvement applied thereto.

Figure 3 is a plan-of the same, with the top plate of the steam-chest removed.

Figure 4 is a plane development of one of the actuating-cams,;to be hereinafter described.-

The object of this invention is to enable the regulator of the engine to so operate the cut-of as to increase or diminish the supply of steam 'to thel cylinder according to the wants of they engine, the invention being intended principally for application .to an engine constructed in accordance with the plan shown in an application for a. patent new pending before the Patent Oce, and also to that class of steam-engines in which two sets ofcylinders of different capacitiesare employed, and in which the steam from the smaller is exhausted in to and employed i n the larger, although the invention possesses merits which render its application valuable Y to-an engine of ordinary construction. c

The invention consists in the combination, with the ordinary valve of a steam-engine, of two drop-plates or auxiliaryvalves,l one at each. end of the primaryvalve, and operating inconnection with ports made through such ends of the primary valve, the auxiliary valves being operated by cams applied to a revolving shaft suitably within the steam-chest, and operated with one unchanging motion by the driving-shafts `of the engine,'a suitable lateral motion being imparted to the said cams by the agency of a sliding rod which extends Ainto the cam-s-hafand is actuated by the regulator, substantially as hereinafter explained.

AIn the accompanying drawings, which represent a steam-engine cylinder constructed in accordance with my application befre referred to, A denotes ythe cylinder of theengine, B C being the steam-ports leading from the steam-.chest to such cylinder, and B the exhaust-port. The primary valve is shown at D, its eccentricred being shown at E. .A chamber, F or G, is formed in the lower part of the 4valve D, and near each end thereof, ports E I being cut through the valve, and opening communication from' the chambers F and G t0 the interior of the steam-chest, which is shown at J, The object of making this chamber and port in each end of the valve is to enable the device to work more directly and freely, and more particularly to facilitate the mechanical construction of it. The drop auxiliary valves K L are disposed within the steam-chest J, and over the ports H I, and are hinged (as shown at a a() attheir inner edges to the opposite side walls of the steamchest, and between the extreme movements of'such ports, in such manner as to form,'with the upper surface of the primary valve and surrounding ports H I, a tight `ioint or seat when Vlowered to their lowest extent, and to be capable of heing raised o' such seats at a proper time and allow steam from thesteam-chest to pass through said ports and into the cylinder. The auxiliary valves K L are provided at' their inner edges withvtrippinglevers or ngers, b, such fingers bearing against the-peri'pheries of twocam's, c d, which slide upon a revolving tubular shaft or sleeve, c, which is suitably supported in bearings,fg, made in the walls of the'steam-chst.

One end of such shaft, which extends through the side of the steam-chest, and is provided at its outer extremity ywith a crank, 71.2, is connected with the driving-shaft of the engine by bevel-.gears in such manner that the revelutions of such shaft shall cause a corresponding number of revolutions of the shaft c. The bearing-surfaces of the cams c d are semicircular in vertical section, and are placed opposite each other upon the shaft e, inorder that. when one of such cams has depressed its valve-lever, the other cam shall be out of contact with its valve;

finger or tripping-lever of such valve, one tripping-lever, viz, that marked b in the drawings, being extended underneath andbearing against tho inner side of its cam, in order to allow of a rotary motion of the cams in one'direction. A rod, z', slides freely within the tubular shaft e, and at its outer endis connected with the govcrnorz of the engine in such manner that-the rising and falling or fluctuations of such governor sh'all cause corresponding lateral movements of the rod z'. The cams c and d are connected to this rodin such manner as to be moved laterally by it, and slide upon the tubular shaft e during the fluctuations of ,the governo1,'whileat the same time they, as well as the rod, are revolved by and with such tubular shaft. To accomplish this, setscrews, 7c and Z, are screwed through each hub of the cams, and extend into grooves, m n, cut inthe periphery of the rod z', two slots, a j), being cat in the tubular shaft for the reception of such screws, and to allow of the lateral motion of thecams upon it. The shape of the cams c d as developed are trapezoidal, as shownin iig.y 4 of the drawings. Y

-As the regulator-balls lower, the rod z' is moved outwardly, and by moving the cams c n. in the same direc- Lion expose a larger amount of their periphery to actuate the lingers a li, and by so doing` hold up or keep open the valves for a greater length of time, and allow more steam to enter the cylinder. A reverse movement of the cams will take place upon increased speed of the regulator, and diminish the quantity of steam admitted to the cylinder, it being understood that the valves K L drop upon the main valve when either finger passes from contact with the periphery of its cam.

We will suppose the main vvalve to be in the position at the extreme left ofits movement, and with the port I beyond and uncovered by the auxiliary valve L, such auxiliary valve being raised bythe action ofthe cam d upon its :linger 6, and' the steam passing from Ythe steam-chest intoand supplying the chamber G ready for Ventrance to the cylinder. The main valve, by the action of' its eccentric, now moves in the`direetion of the arrow thereon, until it arrives at'the position (beit iive-eiglithss'troke, more or less,) in 'which the requirements I ofthe'engine causethe governor to bring the cam d into such a position as to close theauxiliriry valve L, or

let it drop down upon thcupper surface of the mitin -valve and close the port I, thus cutting oil' steam from the cylinder at this end, and allowing -tbe valve D to complete the remainder of its movement in this direetiouwith.- 'out the admission oi' more steam, it being understood that the area oi the auxiliary valve L is suiciently large to cover the port I during such movement. As the valve reaches'its extreme movement in this direction at the right of the steam-chest, and starts to return, 'the auxiliary valve K is opened by the action ofthe cam c upon lthe finger a, and the steam allowed to enter the chamber F through the port H, ready for admission to the lcylinder. As the action ofthe valve when moving inthis direction is the sanie relatively as in the movement last described, its operation will be readily understood. l l

Should the engine be increasing in speed at too rapid a rate, the governor will move the rod z' inwards, and by bringing ashorter or less bearing-surface of the cams c d to act upon the fingers a 6, cause the valves alternately to drop down upon and elosethe ports II and Iquicker, and consequently cut off the steam at a less length of stroke of the piston.` Should the speed of the engine be'deereasing atptoo great an extent, the lowering of the balls of the governor will cause the rod z' to move in an opposite direction, and bring a larger portion ofthe periphery of the cams e i to bear upon the fingers a b, and by keeping the ports HI open for a greater length of time, allowing a larger amount of steam to enter the cylinder.

It will be seen that while one cam is in contact lwith and operating one finger, the blank space of its fellow cum is passing by the other nger without actuating I claim the improved cut-oif. regulating-mechanismherein described, consisting of the auxiliary valves K L, operated by the cams c and d', applied to the shaft c and slides z', the whole operating in combination with the main valve-D and cylinder-ports B and C, to produce the results before set forth and explained.

HENRY O. LOTHRO-P.

Witnesses:

FREDERICK CURTIS, E. C. GRIFFITH.

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