US474000A

US474000A - Intercepting-valve for compound engines

Info

Publication number: US474000A
Authority: US
Publication date: 1892-05-03
Anticipated expiration: 1909-05-03

Description

(No Model.) 3 Sheets-Sheet 1.

, F. W. DBAN. INTERGEPTING VALVE EOE GOMPOUND ENGINES. No. 474,000, Patented May 3, 1892.

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F. W. DEAN.

A 'INTEEGEETING VALVE EOE GOMPOUND ENGINES.

No. 474,000. Patented May 3, 1892.

lwenior Frans Wmiwopeau,

3 Sheets-Sheet 3.

(No Moden.)

F. W. DEAN.

INTERGEP'L'ING VALVE FOR GOMPOUND ENGINES. No. 474,000.

Patented May 3, 1892.

liwenior:

Wnesses: Mmmm. l

y NUNITED STATES PATENT OFFICE.

FRANCIS WV. DEAN, OF CAMBRIDGE, MASSACHUSETTS.

INTERCEPTING-VALVE FOR COMPOUND ENGINES.

SPECIFICATION forming part of Letters Patent No. 474,000, dated May 3, 1892. Application led December 17, 1891. Serial No` 415.360. (No model.)

To all whom it may concern/.-

Be it known that I, FRANCIS VINTHROP DEAN, of Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Intercepting-Valves for Compound Engines, of which the following, taken in connection with the accompanying drawings, is a specification.

My invention relates to intercepting-valves for compound engines and is an improvement upon the intercepting-valve shown and described in the Letters Patent No. 459,779, granted to me September 22,1891; and itconslsts in certain novel features of construction, arrangement, and combination of parts, which will be readily understood by reference to the description of the drawings and tothe claims hereinafter given and in which myinvention is clearlypointed out.

Figure 1 of the drawings is a central vertical section of my improved valve. Fig. 2 isa sectional plan of the same, the cutting plane being on line 1 1 on Fig. 1. Fig. 3 isa horizontal section on line 2 2 on Fig. l. Fig. 4 is a partial sectional plan, the cutting plane being on line 3 3 on Fig. 1; and Fig. 5 is a transverse vertical section through the smokeboX of a locomotive-boiler and the two steamcylinders of a compound engine, with myimproved intercepting-valve casing shown in elevation in its proper relation to the other parts of the boiler and engine.

In the drawings, A is the main casing of the valve, provided with the pipe A', opening from the chamber of said casing and communicating at its outer end with the curved pipe A3, and through it with the curved pipe A4, leading to the steam-chest of the low-pressure cylinder A5 of the engine, the base-flange A2 of the casing A being connected to the upper end of the exhaust-pipe B4, leading from the high-pressure cylinder B5, as shown in Fig. 5.

To the upper side of the casing A is firmly bolted the secondary casing B, provided with the inner pendent tubular hub B', which extends into the chamber of the casing A and is bored out to form a cylinder having two different diameters, the upper portion B2 of which is the larger, as shown and described in said prior patent before cited.

The upper end of the cylinder B2 is closed by the cap B3, having formed thereon or conneoted thereto the pendent pipe or tube D, the bore of which extends in a curved form through the cap B3, and is threaded at ct to receive the end of the pipe D', leading from the interior of the converting-valve D2, as shown in Fig. 5.

The interior of the casing A is provided with the valve-seat a', which is surrounded by the raised rib a2, having the upper portion of its inner surface beveled, as shown at aiin Fig. l.

E is the valve provided with the annular seating-surface b, and the tubularV stem E', formed in one piece with said valve, the outer surface of said stem being iitted closely to the smaller bore of the pendent hub B and the bore of said stem being fitted to form a steam-tight bearing on the pendent tube D, as shown in Fig. 1. The bore of the stem E' extends through the valve E, but somewhat enlarged in diameter, and has formed therein a female thread, in which is screwed the plug E2, the upper end of which is somewhat removed from the lower end of the pendent tubeD when said valve is 'raised to its highest position, as shown in Fig. 1.

The outer periphery of the valve E has its lower corner beveled, as shown at o, and its greatest diameter corresponds to the inner diameter of the rib a2, surrounding the seat a.

The upper end of the tubular valve-stem E has screwed thereon the sleeve-like piston E3, provided at its upper end with the inwardly-proj ecting flange e and the upwardlyprojecting annular lip e', and is prevented from becoming unscrewed from said stem by the screws e2, iitted to tapped holes formed with their axes coinciding with the line of division between said piston-sleeve and said valve-stem, as shown in Fig. 1. The piston E3 has formed in its periphery two circumferential grooves, in each of which are fitted two metal packing-rings d d, and it also has formed therein two smaller grooves j', which assist in preventing the passage of steam from the annular chamber below said piston to the chamber above the same. The valvestem E :is also provided with a pair of metal packing-rings g g, fitted to Work in the lower and smaller portion of the pendent cylinder B', and also with a series of water-packing IOO grooves h h, and has cutthrough it just below said packing-rings a plurality of rectangular or fiat-bottomed radial openings t', said openings being so located relative to the seating-face of the Valve and the lower end of the pendent tube D that the said openings will not begin yto be uncovered by passing below the lower end of said tube until the valve E has descended nearly to its seat and its outer periphery is partially inclosed by the annular raised rib d2.

The exterior of the pendent tube D has formed therein a series ot water-packin g grooves j j and two larger grooves, in each of4 which are fitted two metal packing-rings k lo. all for the purpose ot making a steam-tight joint between said tube and the valve-stem E.

Live steam direct from the boiler is admitted to the chamber B2 through the pipe F, the upper end of which communicates through the tube-sheet with the steam-space of the boiler, as shown in Fig. 5; butiustead of the steam having free access to said chamber through an opening ot' the size of said pipe, as in my prior patent, the steam is wiredrawn through avery small hole Z in the plug or bushing G, as shown in Figs. l and 2.

The tube D has drilled through it just below its junction with the cap B a small hole m, through which steam may pass from the interior of the tube D to the chamber above the piston E to aid in forcing the valve to its seat.

The casing B has formed in its upper part a small vent-hole n, the lower end of which opens into a groove f in the piston E2 when in its highest position, and its upper end com-A mu nicates with the annular chamber formed in the upper packing-face of said casing B. The cap B2 is also provided -with a vent-hole o, extending from the under side of its flange or its packing-face to theinterior of the steampassage through said cap and tube, as shown in Fig. l, whereby any steam leaking from the chamber B2 and passing the lower packingrings d d into said groove f can escape into the tube D, instead of Iinding its way past the upper packing-rings d d into the chamber above the piston E2.

The area of the annular lower end of the piston E2 should be approximately equal to the area of the lower end of the pipe D, so that the pressure of steam in the chamber B2 will nearly counterbalance the pressure of steam in the pipe D, tending to move the valve E downward, and so maintain said valve in its elevated position until steam enough has passed through the small hole m into the chamber above said piston and its stem to overcome the upward pressure of the steam in said chamber B2, when the valve E will be moved downward as fast as the steam can pass through said orifice 'm until the valve has nearly reached its seat, and its periphery is partially inclosed by the annular rib a2, at which time the lower sides of the openings t' i will begin to be uncovered by the pipe D and the steam contained in said pipe and the chamber below it will escape into the chamber A and pipe A', thus causing the speed of the downward movement of the valve E to be reduced to such an extent that it shall com e in contact with its seat without any percepti-I ble slam or jar. By making the openings z t rectangular or with their lower sides flatthey can be placed at suoli a distance above the seating-surface of the valve that said valve may be moved considerably nearer to its seat before said openings are uncovered by passing below the end of the tube D, and when they begin to be uncovered a free passage ot the steam through the tube D, the openings?, e, and the pipe A tothe low-pressure cylinder is obtained with a considerably less downward movement of the valve E than would be necessary if said openings were circular, as 1n my prior patent before cited.

By admitting the live steam from the boiler to the chamber B2 through the small orifice Z in the bushing Gr the upward movement of the valve E, which is started promptlyby the steam in the chamber B2, which is substantially at boiler-pressure, in its continued upward movement will be somewhat retarded by the restricted supply of steam which can pass through said orifice l, and as some steam will remain in the chamber above the piston, which can escape only as fast as it is forced through the orifice m, the upward movement of the valve will be arrested without slam or ar. J The construction shown and described insures the opening of the valve E before the pressure of exhaust-steam in the high-pressure exhaust-passage accumulates above the receiver-pressure, and thus relieves the highpressure piston of the early back-pressure, as the valve E, being acted upon by the steam in the chamber B2 at substantially boiler-pressure, is made to open promptly, when the converting-valve is closed and a passage is opened from the interior of the tubeD to the atmosphere, and is also opened in advance of an accumulated back-pressure on the high-pressure piston.

I have herein described that the cap B3 is connected by a pipe with the convertingvalve, as described in my prior patent, herein referred to, and as a consequence ot said connection it follows that when the converting-valve is closed the steam in the tube D is free to escape into the open air, and as said converting-valve is closed as soon as the high-pressure cylinder begins to exhaust it follows that before the pressure of the exhaust can accumulate above the receiverpressure the pressure above the valve E will have been relieved and the pressure in the chamber B2 will have commenced to raise said vvalve E to open communication to the receiver.

The descent of the valve Ein closing is retarded by the pressure in the chamber B2, the steam in which acts as a cushion and prevents the descent of said valve any faster than said steam can be forced through the orifice Z into the pipe F against boiler-pressure.

l claiml. ln an intercepting-valve for compoundengines, the combination of the casing A, provided with the valve-seat ct', the casing B, provided with the pendent cylinder B', having two different interior diameters, the valve E, provided with the tubular stem E', litted to the smaller diameter of said cylinder, the piston E3, secured to the upper end of said stem and iitted to the larger diameter of said cylinder, the cap B3 for closing the upper end of said cylinder, and the tube D, connected to and pendent from said cap and extending downward to or below the lower end of the cylinder B and fitted steam-tight to the interior of the valve-stem E', an orifice leading from the interior of said tube to a chamber above the valve-stem and piston, and a plurality of radial openings through the valvestem at such a distance above the valve as to be covered by the pendent tube D until the valve has descended nearly to its seat, substantially as described.

2. The combination of the casing A, provided with the seat a' and the annular rib a2, the casing B, provided with the cylinder B', having two different interior diameters, the valve E, provided with the seating-face b and having an outside diameter corresponding substantially to the inner diameter of the rib a2, the tubular valve-stem E', provided with the orifices t' t', made rectangular or having flat bottoms, and also with the packing-rings g, and the packing-grooves hin its periphery, the piston E3, secured to the upper end of said valve-stem and provided with two pairs of packing-rings d d and the packing-grooves f in its periphery, the cap B3, provided with the pipe connection d, the pendent tube D, connected to said cap and extending downward within the valve-stem to a point below the lower end of the cylinder B' and provided in its exterior with two pairs of packing-rings 7c and a series of packing-grooves j and at its upper end with the orifice m, leading from the interior of the tube D to the chamber above the valve-stem and piston, the pipe lF for supplying live steam from the boiler to the chamber B2, and the bushing G, provided with the contracted orifice l, all constructed, arranged, and operating substantially as described.

3. The combination of the casing A, provided with the seat a, the casing B, provided with cylinder B', having two different interior diameters, the cap B3, provided with tube D, opening through said cap at c, and with the escape-orifice o, the valve E, provided with the tube-like stem E', the piston E3, secured to the upper end of said stem and provided with the packing-rings d CZ and grooves f f, a pipe or passage for admitting steam from the boiler to the annular chamber below said piston, and the discharge-orifice n, communicating at one end with the orifice o and at its other end with the interior of the cylinder B' at a point coinciding with one of the grooves fin the piston when said piston is in v its highest position.

In testimony whereof I have signed my name to this specification, in the presence ot' two subscribing witnesses, on this 10th day of December, A. D. 1891.

FRANCIS W. DEAN.

Witn esses:

N. C. LOMBARD, WALTER E. LOMBARD.