USRE763E - Improvement in cut-off and working-valves of steam-engines - Google Patents

Description

2 sheets-sheet 1.

G. H. GORLISS.

GUT-OEE AND WORKING VALVE EOE STEAM ENGINES.

No. 763.y y Eeissued July 12, 1859.

. 2 'sheets-#sheet 2. G. H.. GORLISS. GUT-OFP AND WORKING VALVE POR STEAM ENGINES.

No. 763. Reissue@ July 12, 1859.

INT

UNITED )STATES 'PATENT OFFICE.

'IMPROVEMENT 1N CUT-QFFAND wonKING-VALVES oF STEAMJENGmEs.

Specification forming part of Letters Patent iNo. 6,162, dated March 10, 1849; Reissue No. 200, dated May 13, 1851 Reissue No. 763, dated July 12, 1859.

DlvIsIoN F.

To all whom ibm/ay conce/vt.-

Be it known that I, GEORGE H. ConLIss, of the'citv and county of Providence,- in the State of RhodeJ Island, have invented a new and useful Improvement in Steam-Engines; and I do hereby declare that the following is a. full, clear, and exact description of the principle or character which distinguishes it from all other things before known7 and of the manner of making, constructing, and using the same, reference being had to the acconr panying drawings, making part of this specilication, in which- Figure 2 represents a longitudinal vert-ical section through an engineembracng my im-4 provements, the parts behind the plane of the section being shown in elevation. Fig. 3 represents an elevation ot' the valves and of the valve-gear ofthe same. Fig. 4 represents a plan thereof; Fi g. 5, a separate section representing a link used in the valve-gear; Figs. 6 and 7, a plan and a section of an air-cylinder and piston for checking the motion ofthe Uvalve apparatus.

The same letters indicate like parts in all the-figures. The object of vmy invention is a more eicient regula-tion of the velocity of the steamengine, with a more economical employment of steam therein, than has been' attained by the methods heretofore adopted; and my in vention consists in effecting this object by a new mode of operation, which is embodied in a combination ot' two sets of apparatus, one of which [call the regulator,and the other a liberating valve-gear. The former is an instrument, which, when set in motion, changes the relative position of some of its parts as changes occur in. its velocity, and by` virtue of4 such changes is capable of communicating motion to other mechanism. The latter is a valve-gear which embodies two forces for operating the `steam-valvesthe one for their opening movement, which may be derived from the engine itself, the other for the closing movement, which may be derived from Weights'orsprings or their equivalents; and while the arrangement may be such that the reciprocal operations of. thesetwo forces may' give the proper movements for closing vthe Valves at certain fixed periods of thestroke `of the piston, thereniust be embodied a provision for e'ecting the closing` of the valves at variable periods of the stroke by such. a release of that portion of the valvegear aetuated by one force .from that actuated by the otherforce as will anticipate the time at which 4the valves would be closed if theirv closing were et'e'cted by the return movements of the. opening mechanism.

A liberating valve-gear presents, as l have discovered, peculiar features of adaptation for working in combination witha regulator, as it has the capability Y beyond other species of valve-gear of reducing the amount of power required ofthe regulator in controlling the periods of closing the valves, and also of reducing the range of movementvrequired of the regulator in fulfilling the re quirements of regulation; and though the regulator possesses a very limited amount of available force within the limits of variation in velocity consistent with proper regulation, yet that'force may be so applied to a liberating valve-gear as to be felt at each stroke of the engine, and vary the period ot' eut-oli" to correspond with the changes in velocity.

I have represented my invention in the accompanying dra-wings as applied to an engine embodying various other inventions, a more full description of which is given in sundry patents granted to me bearin g even date herewith. In this engine the steam and the exhaustvalves l l and m m are situated in steam' chests n o 'at each extremity of the steamcylinder. Each exhaust-valve mis attached to one extremity of a4 valve-rod, p, which is ttted atits opposite extremity with a sliding head, q, that is linked by a connecting-rod, r', to one arm, s,fof a bell-crank, t. arm, v, of the bell-crank is connected by arod with a Wrist-pin, to, on the wrist-platex. The latter is secured to a rock-shaft, to which the requisite vibratory motion is imparted by an eccentric, a, through the intervention of an eccentric-rod and an arm, y, secured to the rock-shaft, so .that as the eccentric is caused to revolve with the crank-shaft the exhaustvalves are drawn open and are moved back to close their ports by the power of thevenu gine, with the peculiarities ofmovement inci i dentto the employment of vthe Wrist-motion.

The other ot'the invention set forth in this specification,

a minute description ot' it herein is deemedf unnecessary;

In the valve-gear thus far described each exhaust-valve is connected permanently with the eccentric through the intervention ofthe wrist-plate and its appurtenances, and the exhaust-valves are opened and closed wholly by the power of 'the engine.

The valve-gear for operating the steamvalves differs from that for the exhaust-valves in being-constructed in parts which are separable from each other, so that each valve may be permitted to close independently of the power of the engine. A part of this valvegearis connected permanently with each valve, and in the engine I am now describing the 'part for each valve consists of a double valverod, b', upon which a weight, o, is arranged to act through the intervention of a b'cnt lever or bell-crank, m', to cause the 4valve to close its port whenever the part of the valve-gear connectedv with the valve is separated from the Vremainder of thevalve-gear. The other part of the valvegear consists, in this instance, of two sliding blocks, g g', the'bell cranks ff, having teeth thatfeng'agewith corresponding teeth in thc blocks, the wrist-plate .fr and its appurtenances, and the eccentric a', with its appurtenances', the latter in its revolutions causing the sliding blocks to traverse to and fro. The part ot' the valve-gear connected permanently with each valve is iitted with a variable link .or medium of connection, h',

which is hingedto the valve-rod b', and has an acting face, c, which can be placed in contact with a corxes-pondingface. c, termed upon the adjacent sliding block. When these two faces are in contact, the part ot' the valve-gear connected permanently with the valve is moved along with the remainder, so that the valve is. drawn open and the weight lifted by the power of the engine, the t-wo acting faces c e remaining in contact until a separation is made by a lateral movement of the one to the other. Such a lateral movement is eected in the present example, when steam is to be cut on", by means o f a cam, kf, which is turned by the 4power of the engine, through the intervention of a series of shafts and wheels,

' the last of which is secured to thec'rank-shaft;

and as in this engine the shank of the lilik is not within the range of motion of the cam, a projection, j', is secured to the link, upon which the cam `bears when a separation ot' the one part of the valve-gear'from the other, and the consequent liberation of the steam-valve wit-h its weight fromthe opening mechanism, takes place, and the-valve is then instantly closed by the. power of the weight. As the steam- A valves in the steam engine represented move horizontally, they do not tehd to close by' their own weight, and are consequently closed by means of the weightsvo o', arranged as before described. .l

In order to prevent the jar which would re snlt from the sudden stoppage of the motion of .the weights, each cross-block N has a cylindrical socket, a, Fig. 7, to contain atmospheric air, open toward the steam-cylinder, and a piston, pf, is secured to the engineframe in such a position that itenters the cylindrical socket, and ,iitting the same, compresses the air therein, as the valve closes, to' form an elastic cushion to prevent jar.

In order that each steam-valve may uncover its port at the proper moment to admit steam into the cylinder, the part of the valve-gear connected permanently with the eccentric is moved back bythe operation ofthe eccentric, before the commencement of a stroke a suiiicient distance to permit the acting face of the link to be moved laterally by a spring, t,

within the range ot motion of the opposite acting face of the valve-gear, so that when the valve gear connected with the eccentric again moves forward the two parts ot' the valve-4 gear are connected by the link, and the valve, is drawn open.

In the engine l have represented in the drawings the valves are moved in directions at right angles with the axis of the steam-cylinder, and the valve-gear is adapted to this arrangement of the valves. When, however, the valves are so arranged that't-hey move parallel with the axis of the oyiinder, asis the customary arrangement in slide-valve en gines, the rock-shaft by which theyr are operated Amay with advantage be located in a position different from that described above, and the valve-connections must be adapted to this change. t

We learn from standard works on the steamengine that it has long been well known that great advantages in the economy of fuel would accrue from a cha-n ge in the application of the regulator of stefan-engines, from the throttlevalve to the expansion or cut-off valves; and yet, until the date of my invention the application ot the regulator to the throttle-valve ,was practically the universal rule in. workin g engines in all partsoi' the world,'if we except a few doubtful instances of isolated en# gines of very limited capacity, those constructed with a liberating valve-gear forming no exception to that rule.- One of the exceptions above referred to is described in Tredgolds Treatise on the Steam-Engine;7 atpage 283, article 492; and in the explanations of Plate XVI ot that work, in which plate the engineis exhibited by drawings. Here the reg cam, upon which a puppet or lifting valve was raised, and, after being held up the required -length of time, was lowered to its seat. As this cam wasV designed to govern, by its externalform, the periods ofopening and clos ing the valves, it was elongated, so as to admit within its length all thev gradationsof form requisite for closing the valve at earlier and later periods of the stroke af the piston, and then it was placedA upon au axle in bearings which admitted of its endwise move- 'les :a

ment to the extent whichwas uepessary for bringing, as required, the several gradations offer-m throughout its length, corresponding to the varying .periods of closing, within the plane of movement of the valve-lever.V The range of motion of the regulator was then by the length' of the cam.' This device is rep- IaSBnted 'as applied, by Way of experiment, to whatl isl termed a portable engine.,77 and the .valve operated by it is shown in the drawings side by side with' the throttlevalve'. Others of the exceptional engines re" ferred vto are described in a French-publication entitled Armengauds Publication Industrielle, 850., volume 5, Plate XXXVIII, and volume 6, Plates I and XII, and in the textof those volumes description of those plates and of the enginestherein represented. In` these engines, also, the regulator is-applied to a cam the varying parts of whose surface are made to act upon the valve rods so as to close` the valves at varying periods of the stroke of thel piston; but all these plans, under various arrangements 4of mechanism, embody a common method of operation-the same, substantially, as that in the engine referred to in -Fredgolds Treatise. Another plan is described in a Scotch publication, The Practical Mechanic and Engineers Ma gazine,for April, 1846. vases 165.31.14 166svelume Lwrsistira Off a supplement-al val-ve'placed upon the back ofvv the main steam-valve, uponvwhich it rides as the latter is moved to and fro by an eccentric, and the arrangement is such that at certain times-viz., the varying periods -in the stroke of the piston when the steam is to be cut oi--t-he riding valve is held still by the regulator to allow the main valve to slide lieneath it,l and thus bring the steamport-of the main valve under the supplemental valve, and thereby cut oi' the low of steam into theeylinder, the closing movement-bein g determined by the form of .the cam or eccentric which actu-ates the main valve.

"ihe foregoing published methods of regulating the motion of steam-engines are types of classes of arrangements which have'long been well known; but in all these the closing of the steam-valve through which the regulator operates is dependent upon the form of the cam by which the opening movement of thevalve is eifected, and -not upon a libera. tion from tlie'cam to permit. the valve to be closed by a weight or spring or other equivalent means, so as to anticipate the time at which the. valve would have been closed under the control of its opening mechanism if no such liberation'had taken place. From' these instances it will be seen that the employment case should not turn'.

of weights and springs .in givin'g one movement to the valve, while the other is given -by a cam, does not, of necessity, involvcthe use of aliberating valve-gear, as-they mayl be used for keeping the valve mechanism in contact with the earn, and thereby .keeping-the adapted tothe length of movement required 1 valve in that position relatively tothe other parts'of the-engineA indicated by the form of the cam.

In the case cited from the Scotch publication the operation of the supplemental valvev depends-upon the arm held by the regulator as Well as upon the cam attached to the'erankshaft, which is another instance of the emlployment of two forces for operating the valve without involving the features of a liberating valve-gear.

I' wish it to bedistuctly understood that theinvention which I'elaim under this patent doesnot consist in the form of the regulator employed, nor in the for-rn of .the valves, nor in the form of the valve-gear for opening .the valves, nor in the arrangement of devices for liberating the valves from the mechanism by4 which they are opened.' Various forms of liberating valve-gear heretofore used in steamengines may with good effect be combined 'withjehe regulator so as to control the periods of'liherating 'the 'steam-valves, and thereby 'embody my invention.

In the form of 'steam-engine delineated in Fig. Zthe periods of liberating the valves may be varied by wedgeformed stops or 'cams substituted for the helical camsand connected withthe slide of the'regulaton'which in that Cam-shaped or other forms of stops may be connected with the slideof the regulator by levers, so as to be movedin the plane of vmotion of the valve mechanism in such directions as to 'vary the periods of liberating one portion of that mechanism from the other. It is obvious that by such changes the form, arrangement, and operation of the mechanism of liberation might begreatly varied, While the mode of operation for efecting regulation would remain unchanged.

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

The method, substantially as described, of regulating the velocity of steam-engines by eombinin g a regulator with a liberating valveear. 'g In testimony whereofl I have hereunto subscribed my name. f

GEORGE H. CORLISS.

Witnesses:

HENRY BALDWIN, Jr., JOHN S, HOLLINGSHEAD.

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