US394993A - Valve-gear for compound engines - Google Patents

Description

(No Model.)

W. BPEARSON.

2 Sheets-Sheet l.

VALVE GEAR EUR GOMPOUND ENGINES.

. A WWA/55555 Mgr-0W 1288811888 Deo. 25, 1888.v

2 Sheets-Sheet 2.

(No Model.)

W. E. PEARSON. VALVE GEAR EOE GOMEOUND ENGINES.

No. 394,993. Patented Dec. 25, 1888.

/N VEN TUR;

N PETERS. Phuwumogmpm. wnsningm y UNITED STATES PATENT OEEICE.

IVILLIAM E. PEARSON, OF SAUGUS, ASSIGNOR TO NATHAN H. DANIELS, OF

BOSTON, MASSACHUSETTS.

VALVE-GEAR FOR COMPOUND ENGINES.

SPECIFICATION forming part of Letters Patent No. 394,993, dated December 25, 1888.

Application filed November 26, 1887. Serial No. 256,215. (No model.) Y

To all whom t may concern; steam by using two or more cylinders in con- Be it known that I, VILLIAM E. PEARsoN, nection, and exhausting the steam from the of Saugus, in the county of Essex and State Iirst or main cylinder into the second, and so of Massachusetts, have invented certain new on. In the present instance two cylinders are 5 5 5 and useful Improvements in Valve-Gear for shown arranged inv tandem fashion and i Compound Engines, of which the following is adapted to be worked so as to rotate the crank a specification. in both directions, forward and back. It is My invention relates to steam-engines, and also well known that an engine adapted to more particularly to the valve-gear of the run both ways is provided with two eccen- 6o. 1o same, and has for its object to provide a simtrics-one for the advancing motion, and ple mechanism to operate the valve of the known as the forward eccentric, and one second cylinder of the class of steam-engines for the backing motion, and called the backknown as compound engines. ing eccentric. These eccentricsare connected My invention consists in the combination, to a Iink, so called, the forward eccentric 65 15 with the usual valve-gear of a reciprocating at the top and the backing eccentric at the engine, of an additional eccentric having a bottom of the same. Motion is communicated limited play on the crank-shaft of the engine, to the valve by means of a rod connected to a connection between said eccentric and the the same and leading to the link-block, which valve of the second cylinder, and means is movable in the link to vary the length of 7o' 2o whereby said eccentric is converted by the stroke of the valve.

rotation of the crank-shaft either into a for- Heretofore it has been the custom to use a ward or backing eccentric, and thus caused to second set of eccentrics and links to operate operate the valve of the second cylinder in the valve of the second cylinder. These deunison with that of themain cylinder whether vices render the construction and operation 75 2 5 the crank-shaft is rotated forward or backof engines of this class complicated and eX- ward, as I will now proceed to describe. pensive and occupy considerable space, so

Of the accompanying drawings, forming a that their'arrangement is oftentimes a diffipart of this specification, Figure I represents cult matter. a side elevation of a (tandem) compound By my improvements I do away with the 8o 3o engine embodying my improvements7 the necessity of duplicating eccentrics and links shaft of the same being shown in section. for operating the valve of the auxiliary or Fig. 2 represents a top plan view and partial second engine, and substitute for the second section on the line fr, Fig. l. Fig. 3 represents set heretofore employed more simple and coma section on the line al Fig. l. 4 and 5 pact operating devices, all of which I will now 8 5 3 5 represent detail views, hereinafter referred proceed to describe.

to. Fig. G represents a diagrammatic view of Of the drawings, a a represent steam-cylthe valve-gear of a link-motion engine in inders of common construction, secured in full gear forward and the relation thereto any suitable manner so that they shall be in of my improvements, showing the cylinders line, as shown in Figs. 1 and 2. 9o 4o with the steam-chests removed. Fig. 7 repreb represents the pisto n-rod, arranged in sents a section on line 1/ y, Fig. 6, showing such manner as to pass through cylinder a the position of valves, eccentrics, and pistons and into cylinder d', and constituting a single in Fig. 6. Fig. S represents a view of the piston-rod for the two cylinders, the pistons valve-gear represented in Fig. 6, as it appears b b2 being secured to said rod in any suitable 95 45 in full gear back, showing the position of the manner. In the present instance I have at eccentrics, valves, and pistons as opposite to tached the steam-chests c c to the sides of that shown in Figs. 6 and 7. Fig. 9 reprethe cylinders a a', as the most convenient arsents also a detail view, which will be fully rangement. explained hereinafter. CZ represents the valve-rod which connects roo 5o It is well known that compound engines the main valve g of cylinder a'to the linkare intended for the more economical use of block d. Said rod is pivotally connected to said block, which is moved forward and back by the eccentrics e c through the eccentricrods f j" and link f2, the valve g being thus operated in the usual manner-that is to say, when the link is adjusted by the usual devices, t 7 S, herein described, to bring the rod j' of the forward eccentric into close proximity to the link-block (7', as shown in Fig. o', a :forward rotation is imparted to the crank-shaft 7L of the engine, and when the link is adjusted to bring the rod f of the backing eccentric into the same relation with the link-block, as shown in Fig. S, a backward rotation is imparted to the crank-shaft.

In carrying out my invention l have, illstead of providing duplicates of the abovedescribed devices as the means for operating the valve g of the second cylinder, provided the simpler devices which l will now describe.

7i represents an eccentric loosely ttcd on shaft 7L and adapted to turn easily thereon. (See Figs. l, 2, S, and et.) On said eccentric is litted a strap, 7i?, to which strap is secured an eccentric rod or 'blade, 7f3. Said rod or blade connected at its outer end to a rod, 71", which rod extends to and enters the steamchest c at the forward or outer end of the saine, Fig. 2, where it is connected with the valve g', as shown in Figs. (i, 7, and 8. Ec-

. centric 7L is provided with a project-ion, i, on

one side, adapted to engage with a projection or offset, fi', on a collar, i?, surrounding shaft 7L and secured thereto by set-screws or in any other suitable manner. The position of collar fi2 upon the shaft is such that when the engine moving forward said collar will correspond to the position of the forward eccentric, e, and the projection i of the collar, coming into engagement with projection on eccentric 71 (the saine being loose on shaft 7,) forces the eccentric 7L to conform to the posit-ion of the forward eccentric, c, and remain a forwardmotion eccentric as long as the engine continues to move in that direction. The form of collar i2 and eccentric 7L and its projection f1', and their operative relation to each other, can be best understood by reference to Figs. 3, 4, and li.

The operation ol' the eccentric by collar 'i2 thus far described has been forward, the valves of both cylinders opening and closing their respective ports exactly together, as will be seen by reference to Figs. -l and 7, where the engine is represented as in full gear forward-that is, the piston at the forward end of the cylinders ce a and valves g g have just commenced to open ports j j to admit steam to the pistons 7) Ui, the position of the link being such that the valve ,f/ gets full travel, which can be varied after starting by raising said link, and thereby imparting to valve g a shorter travel, as will be well understood by all skilled in the use of link-motion engines.

Let it be supposed now that the engine is moving forward and it is desired to reverse the direction of themovement. The position of the link will. be changed to that shown in I Fig. S and the forward eccentric, c, will become inoperative or out of gear, and the backing eccentric c, which has heretofore been inoperative while the engine has been in full gear forward, is brought into operative positionv with the link j by its rod or blade being brought into line with link-block f7 and imparts motion to the same, and through it to the valve-rod (7 and valve g, movements wh ich arc the .reverse of those produced by the adjustment shown in Figs. (i and 7, thus causing the valve g to admit steam through thc port j and on the opposite side oli' the piston 71, as shown in cylinder (l, Fig. S. The reverse movement having been given to valve y, the crank-shaft 7i', on which eccentric 72 and collar v172 are located, now rotates backwardly, as indicated bythe arrow in Fig. S, and ol' course et'feentric 7l., bein g loose on said shaft, as stated, g willremain motionlessin the position in which it left by collar i2 before the change ol direction of motion of shat't 7l until the shaft 7l makes a little less than a half-revolution, when. collar i2 engages projection 'i and carries eccentric 7L around, causing it to conform to the position of liacking eccentric c and become also a backing eccentric, operating with the eccentric c', so that both valves g g are worked backwardly in unison.

In Fig. 5 I have shown a different 'l'orm ol' eccentric 71, which, instead ol' having a projection, fi, is provided with a cavity, 7c, which receives a feather secured to the shaft 7L in the saine relation to the eccentrics e e as is collar 2. Then the engine changes direction, the feather carried around with the shaft 7L and engages with the eccentric 71, as shown in Fig.

The travel or movement et' the valve y in connection with eccentric 7L i s what is termed full travelV-that is, said valve being directly connected with the eccentric gets the full throw thereof. The beneiit derived from this arrangement is that the valve g has full travel, and thus gives full opening' to the ports jj, so that the admission of steam to and its escape from cylinder c is not varied, as it would be if valve g were controlled by a linkmotion, and thus baek-pressi'ire on the main cylinder is avoided to a great extent..

I prefer to make the cylinder a otI larger area than main cylinder a for several reasons, the principal one being that when the engine is being reversed the valve g of the second cylinder remains motionless in position. to prevent the escape oi' steam from said cylinder while the shaft is turnin sufiieiently to bring the collar lf2 into engagement with projection "i, and back-pressure on the main piston will be lessened by the enlarged area in cylinder d.

The link f2 is operated by the usual devices (shown in Figs. G and 8)--viz., a saddle, 2, affixed to the link, having a pin, 3, to which. is attached a lifter, et, pivotally connected to an arm, 5, attached to a shaft, t5, and an arm,

7, also attached to said shaft, and a reach-rod,

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scribed, and thereby causing it to become either a forward or a backing eccentric, as said devices may be variously modified without departing vfrom the nature or spirit of my invention.

l claiml. ln a compound engine, the combination, with the main cylinder, its valve, and a linkmotion valve-gear therefor, of the second cyl- Y inder, a valve therefor, an eccentric, h, having a limited play on the crank-shaft of the engine and adapted to conform either to the Aforward or the backing eccentric of the main valve-gear, and a rod connecting said eccentric 72y and the valve of the second cylinder, as set forth.

2. The combination of the valve g, its valvegear, the eccentric h, having a projection, i, strap h2, and rod or blade 71,3, the collar i2, afxed to the crank-shaft and having the proj ection i" the valve g', and the valve-r0d h4, 3o connected thereto and to the eccentric-rod h3, whereby the valve g is operated in unison with the main valve g, as set forth; y

3. In a compound engine, the combination, with the main cylinder, its valve, and link- 3 5 motion valve-gear, of the second cylinder, of larger area than the main cylinder, the valve g of said second cylinder, the loose eccentric 7L, having a projection, t', the collar li2, afXed to the crank-shaft and havingl a projection, i', 4o and the' rods h3 h4, whereby the valve of the said second cylinder is operated in unison with the valve of the main cylinder, as set forth. y

ln testimony whereof l have signed my name 4 5 to this specification, in the presence of two subscribing witnesses, this 12th day of November, A. D. 1887.

lVlLLlAM E. PEARSON. lVitnesses:

C. F. BROWN, H. BROWN.

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