US98725A - Mode of operating valves in steam-engines - Google Patents

Description

UNITED STATES PATENT OFFICE.

GEORGE l'. WASHBURN, Ol" WORCESTER, MASSACHUSETTS.

MODE OF OPERATING VALVES IN STEAM-ENGINES.

Specification formingr part of Letters Patent No. 08,726, dated January ll, 1870.

To all whom it may concern:

lie itknown that LGEORGE I. WAsnBUnN, of Worcester, in the county ol` Worcester and State of Massachusetts, have invented certain new and useful Improvements in Valve- Movemcnts i'or Steam and other Engines 5 and that the following is a sutliciently full and ex act description of my said invention to enable one skilled in the art to which it appertauns to carry it into elect, reference being had to the accompanying drawings, which are made part of this specification.

The primary object of my invention is to so actuate and control a valve that when the motion ot' the steam or other Huid is to be reversed or changed the valve will be caused to move instantaneously, without wait-ing for the accumulation of pressure, and without a possibility of it resting on any dead-point.

To this end I operate the valve in the following manner: First, loading it so that it cannot move; second, applying pressure in the direction in which the valve is to move, insucient to overcome the load referred to, but fully suiicient to move the valve when released third, when the time comes to move the valve and reverse the steam upon the main piston, (or anyother fluid which is to be controlled,) removing or balancing the pressure first referred to, so that the pressure secondly referred to will throw the valve instantaneously and without fail.

My invention, as above set forth, may be embodied in various ways, of which I shall proceed todescribe four, all involving the same principles of operation, and each susceptible of various modifications.

In the drawings, Figure 1 represents a lougitudinal section of a steam-cylinder and piston, with the valve mechanism placed inside the piston, and adapted tobemoved by steampressure. Fig. 2 is a transverse section of the same, in the plane indicated by the line a: fr, Fig. l. Fig.3 shows a transverse section ot' a. part thereof', at y y, Fig. 1. Fig. 4 is a longitudinal section, showing a similar valve located within the piston, and adapted to be thrown by the agency ot springs. Fig. 5 isa longitudinal section, representing the valve mechanism ou the outside of the nia-iu cylinder, and operated by the pressure ol' steam.

Fig. 6 is a transverse section at z z, Fig. 5. Fig. 7 represents, in elevation, the adjacent. ends ol a. steanrcylindcr and ptunp-cylilulcr, with a pis-toured common to both, and an nrln by which the steam valve is thrown` through the medium of springs, as hereinal ter described.

Lilie letters ol' reference indicate like parts in all the figures.

The steam-cylinder A, with its heads a a, may be of any common or suitable const-ruction.

lu the form ol' the invention represented in Figs. l, 2, and 3, l employ a hollow piston, B, the interior of which is divided into four chambers, ol' which two, b b, which are opposite to each other, are always in communication with the steam-supply port S, and the other two, bJ b, which are also opposite each other, are in constant communication with the exhaust-port E.

In order to maintain the communication ol' the chamber bl with the steam-port S at all parts of the stroke, I provide a slot, s, Figs. l and 2, the length of which exceeds that of the stroke of the piston.

The chamber b3 communicates with the exhaust-port E through a similar longitudinal slot, e.

In order to balance the pressure on the opposite sides of the piston, the chamber b communicates with the chamber b, through an open passage, b5, Figs. 1 2, and3; the chamber b' communicates with the chamber b by one or more similar passages, indicated by dotted lines in Fig. 2; and slots s and c* are formed in the walls of the piston, corresponding in area, and diametrically opposite in position, to the slots s and e, respectively.

The steam is introduced to and withdrawn from the ends of the cylinder alternately through ports P' I, whose inner ends are made to communicate with the steam and exhaust chambers alternately by a valve, V, consisting of n hollow cylinder, with three parallel grooves, 1J v v, extending around its periphery. The widthof each of thesegrooves longitudinally oi' the valve is slightly greater than the length ol the stroke or throw of' the valve` within the pistou.

The central groove r communicates con stanti)` with the exhaust. through the ports e b5 e, and alternately with the ports P1 P2 of the piston.

The grooves t" v2 communicate constantly with the steam-chamber b', through the ports s s2, and alternately with one or other ot the ports l1 l, one of the grooves v n2 being used for each of the ports Il l, so as to introducc the steam-pressure to the said ports alternately.

Within the cylindrical valve V is a plug or rod, C, which projects out through the ends of the valve and ol' the piston, and is provided at its longitudinal center with a flange or collar, c, upon which the valve works steam-tight, and which constitutes an abutment tor the steam or other motor to act against, as will presently be explained.

Mv description thus far applies to the form of the invention illustrated in liig. 4, as well as that shown in Figs. l, 2, aud 3. In the illustration given in Fig. 4, springs F l12 are employed to impart the endwise throw to the valve, which, in the illustration shown in Figs. l, 2, and 3, is el'ected by steam-pressure within the hollowl valve..

To ad mitthesteam within it, the hollow valve V, Figs. 1, 2, and 3, is constructed with ports s3 s, communicating with the steanrgrooves 'vl v2, respectively, the said ports being located so far apart that neither of them may pass or reach the central lange orcollar c ot' ithe stationary plug C as the valve moves. Two additional flanges or collars, c c2, on the stationary plug C, serve to close one or other of the ports sas* as the valve moves, the arrangement of the said ports and flanges being such that one of the ports will be closed as the other is opened, and vice versa. The steamchambers at the respective ends of the hollow valve communicate, also, with the exhaustgroove 'v through passages e3 e4, which are, in ike manner, so control ed by the stationary tanges or collars c o that one only of them is open at a time, and the parts c* c s3 s* e3 e* are so constructed and relatively arranged that, while the steam-port si' at one end ot' the valve is open, the exhaust-port e* at the other end will be'open, and s* and e closed; but while the steam-port s* is open, the exhaustpassage e will be open and s3 and e closed.

As the flanges or collars cl c2 are employed only to open and close steam inlets and outlets' to and from the interior of the valve, and not as an abutment for the steam in moving the valve, the said flanges or collars are perforated, as shown in Figs. l aud 3, to allow the steam to pass freely through them, and equalize the pressure on their opposite sides. Additional steamports 8 85 are located near the ends of the valve-chest, so that the valve will close one of them at each extremity of its stroke, but in its intermediate position will be subjected to a balanced pressure of steam upon its ends. G represents the pistou-rod.

Operation: The drawings represent the pis ton at the termination ot its downward stroke, with the valve reversed, so as to cause the upward movement of the piston, which will be el'ected by the pressure of steam admitted through the passages S s s2 o" P2 to the lower end of the cylinder'. At the same time, the pressure of steam admitted through the port s into the valve-chest causes the valve to move upward with the piston, this ett'ect being assisted by the pressure of steam admitted through the port s3 to the upper end of the iuterior of the valve, and acting against the stationary abutment c, the lower end ofthe inteA rior ot' the vulve being' in communication with the exhaust through the passage et.

The upward motion of the valve soon admits steam-pressure into the lower end ofthe valve V, hy uncovering the port- .5" and closing the passage e* by the collar o, and at the same time the steam-port s3 is closed by the collar c1 and the u i er end of the interior ot i il the valve is exhausted through the passage e3. A downward pressure is thus applied to the interior ot' the valve, but this'does not immediately move the valve, because it is overhalanced by pressure upon the exterior of the lower end of the valve, the area of which is greater than that of the interior surface upon lwhich thc downward pressure is exerted.

Before the piston completes its upward stroke the lower end of the valve comes in contact with the stationary collar c, The motion of the valve being thus arrested, the continued movement of the pistou B immediately uncovers-the port s", admitting steam to the upper end of the valve-chest, the downward pressure of which upon the valve balances the upward pressure against the lower end of the valve, and permits the pressure within the valve to throw the latter down against the lower end B2 of the piston, so that the upper end of the cylinder will receive steam through the passages S s s 'v P1, and the lower end will be exhausted through 1*"2 o ez b5 e VE. The' downward stroke lis then made, and the valve again reversed in the manner already described in relation tothe upward stroke. `In each case the entire steam-pressure which is to move tlievalve is applied to it before the time comes for it to move; but is overbalanced by a greater pressure until the proper moment for it to more, when the load being either counterbalanced or removed, the entire pressure of' the steam acts to throw the valve instantaneously.

I am thus enabled to control the pistou with absolute certainty, however rapid its m0- tion, and I avoid all the diieulty commonly experienced with valvcs operated by steam in waiting i'or the passage of steam or the accumulation of pressure.

ln theillustratiou given in Fig. 4 the springs Fl F2 within the hollow valve perform the same functions as the pressure of steam within the valve in the arrangement already described. Fig. 4 shows the position ol the parts at the instant that the valve has been reversed and thc piston has begun its upward stroke. As the piston descended, the valve which rested against the lower head B'L under pressure ot' steam entering through the port S5, compressed the spring Fl nntil the resistance 0f the latter overcame the steam-pressure on the valve. The continued motion ol' the piston then uncovered the port s6, permit ting steam to enter the lower part ol the valvecbest and exert an upward pressure against the lower end of the valve, which, balancing the downward pressure upon the upper end, permits the spring h" to throw the valve instantaneously to the position shown in the drawing, so that steam is admitted to the lower cnd ol the cylinder through the passages s2 122 l", and exhausted from the upper end through P, n, e2, b5, and c. lhe valve V then rises with the piston until the resistance ol the spring F'l overcomes the pressure of steam admitted through the port s, when the port S5 is again uncovered, admitting a balancing pressure to the upper end of the valvechest, when the valve is again instantaneously reversed by the action of the spring F2. Steam is thus admitted to the upper end of the cyliudcr, through the passages 'vl and Pl, and the steam in the lower end exhausted through 1E2 'v e2 and their connections before named. In both these forms of the invention I prefer to provide or permit a slight leak for the steam where the plug U passes through the pistonheads, so that any steam imprisoned in either end of the valve-chest may escape into the exhaust as soon as the valve is reversed; but this leak is not so great as to destroy the cushioning effect on the valve, which is caused by locating the portsssat a little distance from the ends uf the valvechest.

Figs. 5 and 6 illustrate the invention applied under a modified formthat is to say, with the valve working in a stationaryr steamchest, external to the main cylinder and actuated by steam-pressure under control of a central plug, C, which is moved near the termination of each stroke of the pist/0u B by an arm, H, attached to the piston-rod G, and acting against tappets c3 c upon the rod C,'to which the plug C is attached.

Fig. 5 represents the piston approaching the downward termination of its stroke, the arm H having already come in contact with the tappet c, so as to force `down the plug C and valve V until the steam-port $5 is opened so as to admit steam to the upper end of the valve-chest` the downward pressure of which upon the upper end of the valve balances the upward pressure ol'thestcam admitted through the port s. Thel external pressure on the valve heilig thus balanced, the valve is instantaneously thrown down by pressure of steam already admitted to the lower part of the interior of the valve through the port c. B v this motion ot' the valve the passage l"z is plared in communication with steam through and the passage l" in com.

the groove vl,

the exhaust through tinmunication with groove v, and thus the upward stroke ol' the piston is produced, the valve and all its accessories remaining stationary` until the arm ll, striking the tappet. c, moves the plug U upward. 'lhc port s3 is thus uncovcrcd, admittingr steam within the upper end of the valve. which steam, acting against the collar c as au abutnunt, and passing freely through the perforated collarc, exerts an upward pressure upon the valve, lult not Sullicient to overcome the external pressure of steam admitted through the port si to the upper end of the valve-chest. The valve. therefore, does not move until the contact of the collar c* with its upper end raises it suicicntly to uncover the port s", when the external pressure, being again balanced, the internal pressure in the upper end throws the valve up, placing the steam-groove rvz in communication with the passage l", and the eshaust-groove U with the passage P2, and thus imparting thc downward stroke to the`piston.

[n the illustration given in Fig. 7, springs l Iz are interposed between the arm B and tappets c3 c on the valve-rod C', and, instead of employing steam-pressure to load the valve until the time comes to move it, the rod is locked by catches J J2 engaging alternately with the tappets ca and c. In Fig. 7 the piston-rod is represented as moving l'rom right to left. The arm H, carrying the spring l before it, compresses it with considerable force against the tappet c until the said arm, in passing under the inclined face of the catch J', raises it, releasing the tappct c, and causing the valve to be thrown instantaneously by the action of the spring I. When used in a steam-pump operated by exhaust-steam, or any other steam having very low pressure, the arrangement last described has this peculiar value, that the whole area of the main piston is made available for moving the valve th rough the medium of the springs, whereas, if the valve be moved by direct pressure of steam, its area must be large or the propelling force applied to it proportionately small. A balanced valve is preferable for this purpose, but any form of valve may be used.

My principle ol' loading or locking the valve against an elastic pressure, which will throw it instantaneously when the resistance is removed or counterbalanced, may be embodied in any ofthe forms above described, or in various others which will suggest themselves to the skilled mechanic or engineer. For example, the plug C may be as long as the cylinder, as in the present illustration, or it may be shorter. The device will work equally well in a. cylinder ot' any length. Tho plug, projecting from the piston in tbc direction in which the latter is moving, will not act upon the valve until its own motion is arrested by contact willi the c vliiulcr-head, and then it will check the valve, so as lo canse the latter to he thrown by internal pressure, as explained. Again, the plug may be f astened to the cylinder at one end, instead of resting against both heads of' the cylinder; and aga-in, the invention may be used with a, stationary piston :ind n moving cylinder.

The invention is applicable to steam engines, steam-pumps, wfltel motors or meters, or any other purpose where :t valve is required to control the movement of' a piston or its equivalent.

In the common mode of operating valves by steam, they receive the pressure only when their motion should take place, and, unless the steam acts instantly, thel mein piston is liable to strike the cylinder-head. Again, as the valve starts as soon as the pressure upon it equals its own resistance, the vnlvc will not generally act under full boiler-pressure. Nows as (under the ordinary arrangement) the steam which moves the valve is immediately eut off from it, the valve is liable to move over only a part of its stroke before its Steam is cut off. My valve is subjected to full boiler-pressure before it is allowed to move, and this pressure remains on it during a. part of the return stroke of the main piston. Hence, no valvemotion within my knowledge, except when a connection is made with e belance-wheel, can

GEO. I. WAS HBURN.

Witnesses:

EDWARD MELLEN, WM. S. DAVIS.

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