US446406A - Valve-gear - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1.

M. GREENWOOD.

VALVE GEAR.

N0. 446,406. Patented Feb. 10,1891.

INVENTOR @Wwf (No Model.) 2 Sheets-Sheetvz.

M. GREENWOOD.

VALVE GEAR.

No. 446,406. Patented Feb. 10,1891-,

'1NvENToR;

By /zz's Ami/nays,

Unirse @rattles Parleur @lariceo MICHAEL GREENVOOD, OF BELLEVUE, DELAXVARE, ASSIGNOR TO THE HALL STEAM PUMP COMPANY, OF PLAINFIELD, NEV JERSEY.

VALVEBGEAR.

SPECIFICATION forming part of Letters Patent N o. 446,406, dated February 10, 1891. Application tiled December 20,1889. Renewed January 20, 1891. Serial No. 3784=5 6. (No model.)

T a/ZZ whom it may con/cern:

` Be it known that I, MIcHAnL'GREnNwooD, a citizen of the United States, residing at Bellevue, in the county of New Castle and State of Delaware, have invented certain new and useful Improvements in Valve-Gear, of which the following is a specification.

This invention relates to that class of valvegearing for steam-engines wherein the main Io slide-valve controlling the ingress and egress of steam to the power-cylinder is steam-actuated, and wherein the steam for actuating the main slide-valve is controlled by an aux` iliary slide-valve operated by mechanical connection with a moving part of the engine.

The present improvements on this character of valve-gear are especially applicable to steam pumping-engines, and are designed to meet the requirements of this class of engines.

The present improvements consist in the special construction of the main valve, the arrangement of the ports between the main valve and the auxiliarycontrolling-valve, the means for connecting the two valve-chests to the steam or power cylinder, and in the mechanical connection between the auxiliary valve and the moving part of the steam-engine, which in this case is the pistonrod.

The improvements are illustrated in the 3o accompanying drawings, in which- Figure l is a vertical longitudinal section of the steam-cylinder of a pumping-engine. Fig. 2 is a vertical cross'section in a plane indicated by the line 2 2 in Fig. l. Fig. 3 is a partial vertical cross-section in a plane indicated by the line 3 3 in Fig. l. Fig. 4 is a plan view of the valve-seat for the auxiliary valve. Fig. 5 is a bottom view of theauxiliary valve.

A is the steam or power cylinder. l is the piston thereof.

C is the piston-rod.

D is the steam-chest of the main valve.

F is the valve-chest of the auxiliary valve,

and G is the sliding auxiliary valve.

The auxiliary valve G is connected rigidly to its reciprocating valve-rod Il, which extends outwardly through an elongated stuffing-box I, and is connected by a link J to the 5o short arm of an oscillating lever K. The long lower arm of this lever forked, and

the two forks a are each provided with an inwardly-projecting rounded stud l1. The two rounded studs enter on opposite sides and fit into the annular groove c of the collar L, which is rigidly secured to the piston-rod C. Owing to this construction the lower end of the lever will be moved back and forth with the piston-rod, while the grooved collar and the therein entering studs permit the verti- 6o cal movement of the lower end of the lever and at the same time insure a constant close fit between the piston-rod and lever. The connection between the upper short end of the lever K and the link J is an adjustable one, so as to allow a variable extent of travel to the auxiliary valve G. The upper end oi the lever K is provided with a longitudinally-extending elongated slot d, in any desired portion of which a transverse bolt e is held by a locking-nut f. On a part of this bolt the link J is pivotally hung.

The main slide steam-actuated valve E is connected to an actuating balanced piston M, which lit-s and slides in cylindrical por- 75 tions g g at opposite ends of the steam-chest D. The central portion of this piston is recessed around its entire periphery, and this central annular recess 7L is in constant communication with that portion of the steamchest into which the live steam enters. The main-valve-actuating piston is formed with a steam duct or passage t' extending longitudinally through it, said d uct or passage having contracted openings or ports .7' j at opposite ends of the piston, through which contracted openings or ports the said duct or passage communicates with balancing spaces or chambers 7o 7o in the steam-chest beyond the respective ends of the piston. The duct or passage t is at its central portion in constant free connnunication with the live steam by means of a transverse duct Z, which opens into the annular space 7L. The live steam can thus freely enter the duct t', but is retarded and hindered in passing therefrom into the balancing spaces or chambers 7U' 7U' at opposite ends of the valve-actuating piston by reason of the reduced size ot the contracted ports ,j j. Both ends of the piston being in constant communication with the live steam it is con scquentl y normally a balanced piston.

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The valve-seat N of the auxiliary slid e-valve G is provided with a central exhaust-port nl, and two live-steam ports fn. `n on opposite sides ot the exhaust-port. An exliaiist pas sage o leads from the exhaust-port to the air or a condenser, and oppositel y-extendin g passages or ducts p p lead trom the live'ports 'n a, respectively, to the two spaces or chambers 7c 7e at opposite ends ol' the main-va1ve io actuating piston. To provide for cushioning the piston the ducts p p open into the spaces or chambers 7s t a short distance from the extreme ends of the chestfD. The ports mn n are approximately the same in length as in i5 width, being preferably circular, and-in cross-v section each should have an area approximately equal to that of the-duct' in the mainvalve-actuating piston.

Theauxiliary valve G'has on its under side zotwo vtransverseports q q,-respectively, near the opposite ends ofthe valve, the longitudinal distanceibetweenthe axes of these ports beingsubstantially equal to the normal-e ltent ofy travel of the valve. The width of 2 5 each port q is substantially equal yto the diameter of one ot' Vthe ports m n n, andthe length of f teach" port q is equal to the'distanee between the exhaust-port m and one of the live ports `n :increased by the diameter ofk one of the ports.

*3e `The-two ports q q'extend, respectively, in oprl'-posite directions from the longitudinal axis i `of the'valve, so that when the valve reaches 'thelimit of its travel inr one direction it establ Klishes communication between fone live port n and the exhaust, and when it reaches its limit of movement in the `opposite direction communication is established between the other live-steam port and the exhaust. It

Will'beobserved that during the intermedidictate"` portions'of the-travel of the auxiliary walve th`e-ports m n n areall closed,and that f itis only just at' the ends of the travel of the valve that-the ports are uncovered. `Then the auxiliary valve vreaches its limit of Amo- 45ftion in one direction, communication isy es- :.tablislied between the exhaust and one of y ythe spacesor chambers 7th at one end-of the -'tmain-valve-aetuating piston, thus relieving ffthepressurcat that end. The piston is con- 5oL scquently moved'in that'direetion bytliecxcess 'of steam-pressure at its opposite end.

Vllhemovcment ot the pistonVV closes the opening leading'ifrom' the; spaces or chambers 7a l intofthe duet j), and the'pressure at opposite 55 :ends of the piston isequalized by the live steam passing through the contracted ports 7' jand equilibrium is restored, so that when the auxiliary valve reaches its limit of travel Yin `the opposite direction (thus relieving the 6o pressurefat the other end of thepiston') the first action is repeated.

\Owing tothe described construction the Amain valve shifts only'atthe proper inter-l -vals and at the'saine time the auxiliar)7 valve 6 5` is a constantly moving one, so' that the move- 4v`ments of the valves are effected without employing tappets, springs, or otherl noisy or striking devices. Y

rlhe various parts of the steam-chest D and the valve-chest F are constructed so that they can all be securely fastened to the power-cylinder A by the employment ci two throughbolts O O.

The steamchest D is formed of a solid casting havin'g two vertical passages r r for the insertion of the bolts formed in lateral ribs S s on the casting. The valve-chest F is formed with its sides and ends in a single hollowed casting, and is formed withlaterally-extend ing ears or ribs t t, having bolt-passages u u in line with the passa-ges o' vr, and the top plate or cover P of the valvechest is provided with laterally-extending ears or ribs w w; having bolt-holes min line with-=the-passages u u, so that the same'bolts secure the valve-chest and itstop plate -in position. Theboltsscrew into ears y, y 4on thesidesofithe' steam-or poweireylinder, so as-to retain the casting in place. This construction renders the parts readily and economicallyattachable and detaeliable.

Iy claim asmy inventionl. A valve-seat-having a central `exhaustport and two live-steam ports on each side of said exhaust-pornin combination with a slidevalve having -two transverse ports near itsoppesite ends', said ports-extending iirOpposit-e directions lfrom the longitudinal axis'ot said valve, the longitudinal distance -betweensaid ports being substantially equal to thc-extent of the travel of the valve, and eachfport being long enough to reach trom'said exhaust port to one et said live-steam'ports, substantially as set forth.

2. The main valve of a steaiii-cylinder, a balanced actuating-pistontherefor having a longitudinallyextending duct in constant communication with the live steam and communicating at opposite ends -Withbalancing spaces or chambers at the respective ends of the piston, in combination with a valve-seat having a central exhaustport and-two flivesteam ports on each side of `said exhaust-port,

said two live ports communicating withfsaid balancing spaces or chambers, respectively,

and an auxiliary slide-valve having two transverse ports near its opposite ends, lsaid ports exten ding in oppositev directions from 'thelongitudinal axis ofv said auxiliary valve, thelengitudinal distance between said ports being substantially equal to the cxteiit'of the travel of said auxiliary valve, and eachport being long enongli to reach from said exhaust-port to said live-steam port, substantially as set forth.

3. The main valve of a steain-cylinder and a balanced actuating-piston therefor having a longitudinally-extending ductin constant kcommunication with the live steamy-said duct having contracted ports at opposite ends of the piston communicating with spaces or chambers at the respective ends of thepiston,

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4. The steam actuated main valve of a steam-cylinder, the reciprocating` piston, and the piston-rod, in combination with a constantl y-l'noving auxiliary valve Which controls the movement of said main valve, said eonstal'itly-inoving valve being mechanically conneeted with said piston-rod so as to move in unison therewith, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence ot' two subscribing 25 witnesses.

MICHAEL GREENWOOD. 1Witnesses:

GEORGE Il. FRASER, JNO. E.` GAvIN.

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