US337644A - John young - Google Patents

Description

(No Model.) t

J. YOUNG.

DASH EOTr EoE STEAM ENGINES.

. Patentd'-MaE. 9, 1886.

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ilNTTnn STATES PATENT Ottica.

JOHN YOUNG, OF NEWARK, NEW JERSEY.

DASH-POT FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent. 210.337.644, dated March 9. '1886.

Application tiled December 21, 1885. Serial No. 186,293. (No model.)

.To all whom it may] concern:

Be it known that I, JOHN YOUNG, of Newark, Essex county, in the State of New Jersey, have invented a certain new and useful Improvement in Dash-Pots for Steam Engines, of which the following is a specification.

I employ the term dash-pot77 to indicate the device-one for each steam-valve-whieh, when the valveisliberated, iirst acts to prompt- ]y effect the closing and then to gently arrest the closing motion. I have devised important improvements in thc construction. I make the dash-pot annular, with the central portion Y over this central post.

the highest. Thefgipiston is guided on a smoothly-turned central post. I provide means l'or maintaining a`nearl y perfect vacuu m The annular chamber which surrounds the base of this post imprisons a quantity of air, which resists the descent of the piston near the bottom and gently arrests the mot-ion. Iattach particular importance to provisions for allowing the air to escape downward from this chamber into another conveniently arranged below. On the rising ofthe piston with the opening of the valve, air is drawn upward again from the said lower chamber. I provide for taking the air downward from and delivering it to the chamber at two or more different levels and for adj ustably contracting the effective area of these openings. The interior ofthe cylinder which incloses the base of the piston is formed` with an offset, as is common in this class of devices, allowing the air to flow out andthe piston to descend freely during the first part ofthe closing movement. Below this offset I bore'conically, so that as the' piston descends the air below is at iirst imprisoned only partly, the tightness ofthe tit increasing as the piston descends. I provide means for introducing oil to the vacuum-chamber on the top of the central post, and for entirely excluding the air after each supply. The reservoir of oil thus provided insures efficient lubrication. It will now be understood that at each opening of the valve the piston, in the form of an inverted cap with cylindrical sides and a sufficiently broad bottom rim, is drawn up forcibly, making a vacuum under the high central portier., which remains unbroken during the whole movement. Under the rim of the piston no vacuum is formed at any period, because the air can enter with tolerable freedom through the contracted passages from belov.T during ali portion of the rising movement, and as soon as the piston rises well into the conical portion of the bore and at all the later stages ofthe opening movement the air is admitted freely from above. On the liberation of thevalve my piston descends rapidly and is arrested gently. the drawing in and forcing out of the air through the contracted passages in the lower portion are smothered by its communication with the chamber below instead of into the open air. This makes the operation silent. I interpose leather in the vacuui'i'i-chamber in the center, and also in the annular arrestingchamber, to soften the concussion, when from any cause the descent is not otherwise sufficiently arrested. I'allow the piston to turn around freely on the central post. motes itswearing uniformly. A circular groove in the bottom of the annular arrestingchamber puts all portions in free communication with the one ormore contracted passages through which this chamber communicates with the chamber below. The central post is hollow, and, by the aid of a valve mounted in the upper portion, delivers downward the contents ot' the central or Vacuum chamber at each descent ofthe piston. All the parts are easy of access for examination or repairs.

rIhe accompanying drawings form a part of this specification, and represent what I consider the best means of carrying out the invention.

Figure l is a vertical central section. Fig. 2 is a plan view. Fig. 3 is a corresponding View ofthe central portion with the piston relnoved. Fig. 4 is a horizontal section on the line x :v in Fig. l.

Similar letters of reference indicate corresponding parts in all the figures where they occur. n

It will be understood that in my dash-pot, as in others, the piston is lifted and liberated at variable periods, according to the point at which the steam is to be cnt off. 0n being liberated, it descends rapidly, and at the termination of the downward movement is arrested gently.

The sounds produced byl This pro-g lOO A designates the fixed portion of the appa` ratus. I will use additional marks, as A', when necessary to indicate special parts thereof.

A is a portion of the bed-plate of the engine. (Not represented.)

A2 is the base-plate, faced upon A, and held firmly down by suitable bolts inserted through lugs Ai. (See Fig. 2.) In its upper face is a circulargroove, a. A passage, m, leads down from this groove into a chamber below.

A4 is what I term the post,7 a hollow cylindrical casting, formed in one with A2, finished on its exterior, and grooved horizontally, as indicated by a. The whole is inclosed in a deep rimor hollow cylinder, A A, The lower portion, A5, is bored cylindrically for alittle distance up from the base, and tapering above. At ai is an offset, the interior space being considerably enlarged at this level. Above this offset the rim AU extends upward further. The annular space between the post A4 and the rim A5 AG is open at the top. A passage, fn, (see Fie'. 1,) is drilled or otherwise produced in the position represented. It is controlled by an adjustable screwplug, N. The passage m is controlled by an adj ustable screw`pl ug. M.

B is the piston, certain portions being designated when necessary by additional marks, as B B.

B is a cylindrically-bored portion fitting closely around the post A4, and free to move up and down and also to turn around thereon.

B2 is a stout bottom flange, and B1 the top, provided with a screw-threaded neck, spherically bored.

C is a spherically-bored cap, having an octagonal exterior and a screw-threaded interior, with a. properlyshaped aperture in the top to allow vibration to the operating-rod D, which is formed with a spherical lower end, D', and is properly connected at the upper end to the Valve-operating mechanism. (Not represented.)

Eis a removable casing tapped into the top of the postA4, and forming a seat for an automatic valve, G, mounted within and held up gently to its seat by a coiled spring, H, which latter abuts on the removable plug E', fitted in the base oi'E. There is avertical winged space around the valve H. The upper end of the casing E is hexagonal. T.Vhen the rod D is disconnected and the piston is lifted off, the casing E may be convenientlyinserted and removed by applying an ordinary wrench.

I is an annular piece ot' soleleather secured by screws z on the top ofthe post A4.

J is an annular piece of sole-leather secured by screwsj on the lower face ofthe flange B2.

A screw-plug, P, serves to tightly close an orifice through which a small quantity of oil should be introduced at short intervals.

Operation: At each opening of the steamvalve (not represented) the piston is forcibly raised, thereby forming a cylindrical chamber over the post A4, and an annularchamber under the flange B". In the top chamber is, at each elevation of the piston, a nearly perfect vacuum. The annular chamber under the flange B2 is always filled with air, the air being drawn in at the commencement through the apertures m and n, and at a later stage in the rising motion of the piston flowing freely in from above, as will be obvious. The pressure of the external atmosphere over the top chamber contributes with gravity to induce a prompt descent ofthe piston so soon as itis liberated. As the piston descends, it con1- lnences to imprison the air under it. In the last part of the descending motion, after the lower edge ofthe piston has traversed the tapering part of A5 and reached the cylindrical portion, the only escape for the air below is through the passages m and n. The plugs M and N should be set so as to open these passages just suiiiciently to allow the valve to close rapidly, but without.- concussion. Sound is produced by the rapid movement ofthe air through the passages m and n; but my arrangement insures that this is so eit'ectually conlined to the bottom chamber, a, that it is inapprcciable in the engine-room.

The leathers I and J perform an important function. It will often occur in practice that in the effort to adjust the screw-plugs M and N to allow the valve to shut very promptly the piston will not be quite enough cushioned, and will strike on the bottom. insure that such contact will never be metal with met-ai, but always through the interposition of these leathers. So soon as the concussion attracts attention, one or both thescrews M and N should be set in alittle, so as to retard the escape of air from under the pistou a little more. Concussion will thus loe removed.

I have shown four horizontal grooves, a, extending around the post'A4. There may be one or a series ofsuch grooves, one above another. Their function is to form pockets, which have the effect to retard the ow of air or oil through the joint, which is necessarily easy between the post A4 and the interior of the piston B. One alone may serve.

The vacuum-chamber over the center post is marked rv, the annular cushioningchamber under the flange B" is marked y, and the bottom chamber,f which receives the blasts of air through the orilices m and n at each descent and suppresses the sound, is marked z.

The groove a2,4 turned orotherwise produced in the upper face of A2, insures a free communication from all parts of the cushioningchamber to the orifice m, even when the piston is quite down.

Further modilications may be iliade. The

proportions of the parts may be changed. The post A* may be more or less high. l can vary the form ot' the controlling means M and N, which adjust the area ofthe passages l'or the flow of the air from the annular chamber under the piston into the bottom chamber at each descent.

Parts of the appara-tus maybe used without the whole. I can dispense with the upperpor- The leathers ICO IIO

tion of the rim A5. The eect of this portion of the apparatus is mainly to protect theinterior parts from injury from the introduction of hard substances or other cause when the piston is raised.

I claim as my invention- 1. The post A4, made hollow, as shown, in combination with the valve G, mounted in the interior near the top, a spring, H, and piston B, adapted to form a tight vacuum-chamber over the post, and an annular cushioningchamber or dash-pot around the bottom, as herein specified.

2. The post A4, piston B, and cylinder A6 A, tapered below the offset, and arranged for jointoperation as herein specified.

3. The piston B, cap C, and rod D, with its spherical end D', in combination with each other and with the post A*,valve G, 'and cylinder A5, arranged for joint operation as herein speciiied.

4. In adash-pot, the bottom chamber, z, and

passage m between the same and the cushioning-chamber 1 in combination with the piston B and operating means D, arranged to serve as herein specified.

5. The duplicate passages m n and controlling means M N, leading' from differentleVe-ls in the dash-pot, communicating with the same bottom chamber,and arranged to serve as here- 3o in specified.

6. In a dash-pot, in combination with the rim A5, piston B, operating means D, hollow post A, valve G, and spring H, the removable casingE, adapted to serve as herein speci- 35 fied.

In testimony whereof Ihavehereunto set my hand, at New York city, New York, this 19th day of December, 1885, in the presence of two subscribing witnesses. e

JOHN YOUNG.VV

Witnesses:

WILLIAM S. WATTS, Crus. H. SoNN.

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