US1025638A - Compound engine. - Google Patents

Description

G. J. MELLIN.

COMPOUND ENGINE.

'APPLICATION FILED DEC. 22, 1911.

` 1,025,638.A v Patented May 7, 1912.

2 SHEETS-SHEET 1.

lllllliil C. J. MBLLIN.

GOMPOUND ENGINE.'

APPLIGATION FILED M022, 1911.

Patented May 7, 1912. A

2 SHEETS-SHEET 2.

UNITED sTATEs PATENT oEEioE.

CARL J'. vlV.[,`li.I1L]N, OF SCHENECTADY, NE-W YORK, ASSIGNOR TO AMERICAN LOCOMOTI'VE COMPANY, OF NEW YORK, N. Y., A. CORPORATION 0F NEW YORK.

COMPOUND ENGINE.

To all whom t may concern Be it known that I, CARL J. MELLIN, of Schenectady, in the county of Schenectady and State of New York, have invented a certain new and useful Improvement in Compound Engines, of which improvement the following is a specification.

My invention relates to mechanism for enabling the operation of a compound engine to be effected, as from time to time desired, either normally, that is to say, by the piston of the low pressure cylinder being actuated by steam exhausted from the high pressure cylinder, or in the manner of a pair of single expansion engines, c'. c., by the direct admission of boiler steam to the low pressure cylinder as well as to the high pressure cylinder.

My present invention is an improvement upon that for which Letters Patent of the United States No. 519,407 were granted and issued to The Richmond Locomotive and Machine Vorks, as my assignee, under date of May 8, 1894, and its object is to provide an appliance of the general type above specified, in which a suiiicient area shall be maintained through the balancing piston to insure its proper action; distortion of the guide of the intercepting valve by imperfections or variations in position of the rough wall of the chamber of the balancing piston effectually prevented; ample bearing surface provided to act as a guide for the stem of the intercepting valve; and proper balance of the valves maintained, without impairment by leakage past the packing rings.

The improvement claimed is hereinafter fully set forth.

In the accompanying drawings: Figure 1 is a longitudinal central section through the intercepting and emergency exhaust valve mechanism of a compound locomotive, illustrating an application of my invention, the parts being shown in the positions occupied when working live steam direct in both cylinders of the engineLFig. 2, a similar view, with the parts shown in the positions occupied when working compound; Fig. 2a, a transverse section through the balancing piston, on the line b b of Fig. 2; Fig. 3, a view, half in elevation and half in longitudinal central section, and on an enlarged scale, of the sleeve of the intercepting valve stem; Fig. 4, a partial longitudinal central Specification of Letters Patent.

Application filed December 22, 1911.

Patented May 7, 1912. serial No. 667,318.

section, on a further enlarged scale, through the intercepting valve stem; Fig. 5, a plan or top view of the balancing piston; and,

Fig. 6, a transverse section, on an enlarged scale, through the reducing valve casing, on the line a a of Fig. 1.` i

The mechanism in which my improvement is applied is fitted and operates in a casing, 1, which constitutes the passage way for the exhaust steam from the high pressure cylinder to the low pressure cylinder of a compound engine, or to the atmosphere, accordingly as the engine is working compound or single, and which, in a locomotive engine, is ordinarily a portion of one of the cylinder saddles. A receiver 2, in the casing, 1, is in constant communication with the exhaust passage ofl the high pressure cylinder of the engine; a passage, 3, leads from the casing to the valve chest of the low pressure cylinder; and an emergency or direct eX- haust passage, 4, leads from the casing to an exhaust vpipe discharging into the atniosphere. A balancing chamber, 5, is interposed between the receiver, 2, and the direct exhaust passage, 4, and a direct or live steam passage, 6, leads from the boiler to a reducing valve chamber, 7, formed in a casing, 8, fixed to the main casing, 1, said chamber, 7, communicating, through ports, 7H, with the passage, 3, leading to the low pressure cylinder, when said ports are uncovered by a reducing valve, 9, as hereinafter described. A dash pot cylinder, 10, closed by a head, 10a, having a port, 10b, leading to the atmosphere, is formed on the outer end of the casing, 8, and is .fitted with a suitably packed piston, 11.

The discharge of exhaust steam from the receiver, 2, to the low pressure cylinder passage, 8, is controlled by an intercepting valve, 12, fixed upon one end of a valve stem, 12a, upon the opposite end of which is secured a balancing piston, 13, controlling a passage, 5a, leading from the receiver, 2, into the balancing chamber, 5, The balancing piston, 13, is provided with circumferential ports, 13a, and small through ports, 13", theaggregate area of which is substantially less than that of the ports, 13a, the function ofthe ports, 18h, being to maintain a constant equilibrium of pressure between the receiver and the balancing chamber, except upon the unseating of an emergency exhaust valve, 14, which controls communication between the balancing chamber, 5, and the direct exhaust passage, 11. -T he combined area of the circumferential ports, 13, in the balancing piston, is slightly less than the area of the opening controlled by the emergency exhaust valve, 14, in order that, as the exhaust steam passes through the ports, 13a, on its Way to the direct exhaust passage, a constant pull Will be exerted upon the balancing piston, tending to hold the intercepting valve closed and prevent iuttering. The emergency exhaust valve, 14, is formed integral with, or fixed to, a piston, 15, working in a cylinder, 16, to which steam is admitted by a supply pipe, 16a, controlled by a valve (not shown) which is manually operated by the engineer. The piston, 15, is returned to normal position, in which the emergency exhaust valve is closed, by a spring, 17, bearing at one end on the cylinder, 16, and, at the other, on a disk, 18a, fixed on a stem, 18, secured to the piston, 15.

The` stem, 12a, of the intercepting valve, is made hollow or tubular, from a point adjacent to the intercepting valve to its upper or outer end, adjacent to Which the dash pot piston, 11, is secured upon it. The reducing valve, 9, before referred to, is formed upon a sleeve, 9a, Which is fitted freely on the stem, 12a, of the intercepting valve, and controls communication, thro-ugh the ports, 7a, between the live steam passage, 6, and chamber, 7, and the passage, 3, leading to the low pressure cylinder. The sleeve, 9a, is reduced in diameter, relatively to the reducing valve, 9, and said valve and the sleeve or lesser diameter lit in corresponding differential bores in the casing, S. The sleeve, 9a, is provided with packing rings, 9b, and is turned down to form a longitudinal recess, 9C, and bleed holes 9d, are formed in its Wall. The portion of the stem, 12, of the intercepting valve which is Within the sleeve, 9a, is provided "With packing rings, 12", and it is turned down to form a longitudinal recess, 12C, Within Which bleed holes, 12d, extend from its central bore to the periphery of the recess, 12. Said recess pre-vents the sealing up of the bleed holes in any position of the sleeve, and enables leakage past the valve to escape to the atmosphere, through the central bore of the valve stem and the dash pot cylinder, 10.

In the operation of the mechanism above described, when it is desired to change the Working of the engine from compound to simple, steam is admitted to the cylinder, 16, by the engineer, the pressure thereof on the piston, 15, unseating the emergency exhaust valve, 14, and thereby suddenly releasing the pressure in the balancing chamber, 5, on the adjacent side of the balancing piston, 13. This reduction of pressure on said piston causes the receiver pressure, acting on its opposite side, to move it to the position shown in Fig. 1, thereby seating the connected intercepting valve, 12, which operation is effected without bleeding the entire reservoir and thereby stalling the train, as is ordinarily the case with intercepting valve mechanisms of other constructions. It may be here noted'that, as before explained, the small through ports, 13", in the balancing piston, maintain an equilibrium of pressure in the receiver and the balancing chamber, at allv times except upon the opening movement of the emergency cxhaust valve, and that, when the intercepting valve is seated, it is held in such position Without fluttering on its seat. Then working as a simple engine, the exhaust steam of the high pressure cylinder is discharged through the direct exhaust passage, 4;, to an independent or emergency exhaust pipe, and live steam is admitted to the low pressure cylinder by the reducing valve, 9, said steam being throttled and reduced in pressure in its passage through the ports, 7, leading to the passage.

In order to change the Working of the engine from simple to compound, steam is exhausted from the cylinder, 1G, by the engineer, whereupon the pressure acting on the top of the emergency exhaust valve, 14, in conjunction With the spring, 17, seats said valve. Equalization of pressure then takes place in the reservoir, 2, and balancing chamber, 5, and the intercepting valve, 12, is unseated by the building up of the reservoir pressure against it. The exhaust steam of the high pressure cylinder is thereupon discharged to the lo7 pressure cylinder, through the passage, 3, and the supply of live steam to the low pressure cylinder is cut oif by the closure of the ports, 7a, by the reducing valve, 9.

The practical advantages of my improvement Will be obvious to those skilled in the construction and operation of compound engines, in the particulars of its embodiment of means for insuring the true rectilineal movements of the intercepting valve to and from its seat; maintaining normal and sufficient area for the passage of steam from the receiver to the emergency exhaust valve; preventing undesired opening or fluttering of the intercepting valve; and maintaining proper balance of said valve Without impairment by leakage of steam past the packing rings of the reducing valve.

I claim as my invention, and desire to secure by Letters Patent 1. In a compound engine, the combination of an intercepting valve and a cylindrical balancing and guide piston, said piston being provided With a peripheral main discharge port, and with through balancing ports of lesser area.

2. In a'compound engine, the combination of an intercepting valve, a stem on which said valve is secured, an emergency exhaust valve, and a balancing piston secured on the stem of the intercepting valve and working in a cylindrical opening in a partition interposed between the intercepting valve and the emergency exhaust valve, said piston being provided with a peripheral port and with through ports of lesser area. A

3. In a compound engine, the combination of an intercepting valve, a stem on which said valve is secured, a sleeve mounted on said valve stem, a reducing valve fixed on said sleeve, a casing in which said sleeve and reducing valve work, and which is provided with circumferential ports, controlled by said valve, establishing communication between a live steam passage and a low pressure cylinder, and a balancing piston fitting in a balancing chamber and connected to the intercepting valve.

4. In a compound engine, the combination of an intercepting valve, a stem on which said valve is secured intermediate of its ends, said stem being tubular throughout a portion of its length on the side of the valve opposite the seating face thereof and open at its end to the atmosphere, a sleeve mounted on the tubular portion of said stem, a reducing valve fixed on said sleeve and controlling communication between a live steam passage and a passage to a low pressure cylinder, and means for discharging leakage past the reducing valve through the tubular portion `of the valve stem.

5. In a compound engine, the combination of an intercepting valve, a stem on which said valve is secured intermediate of its ends, said stem being tubular throughout a port-ion of its length on the side of the valve opposite the seating face thereof and open at its end to the atmosphere, a sleeve mounted on the tubular portion of said stem, and having a circumferential recess, a reducing valve of larger diameter fixed on said sleeve, a casing in which said sleeve and reducing valve work and which is provided with ports controlled by said valve, establishing communication between a live steam passage and a low pressure cylinder, radial ports leading through the wall of the sleeve, and similar ports leading through the tubular portion of the valve stem.

6. In a compound engine, the combination of a casing containing a receiver and having connections to a high pressure cylinder exhaust passage, a low pressure cylinder supply passage, an emergency exhaust passage, and a live steam passage, an intercepting valve fixed upon a stem between the tubular and solid portions thereof, a dash pot cylinder to which the tubular portion of the valve stem is open, and which is itself open to the atmosphere, a balancing and guide piston fixed to the valve stem and working in a passage between the receiver and a balancing chamber, an emergency exhaust valve controlling communication between said chamber and the emergency exhaust passage, a sleeve fitting on the tubular portion vof the valve stem, a reducing valve fixed on said stem, and a casing in which said sleeve and reducing valve are iitted to work and which is provided with peripheral ports controlled by the reducing valve and establishing communication between the live steam passage and the low pressure cylindersu pl assage.

P y p CARL J. MELLIN. lVitnesses HAL. R. STAFFORD, A. G. Es'rns.

Copies of this patent may be obtained for ive cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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