US100814A - Improvement in steam-engine slide-valves - Google Patents

Description

\ city and county of San Francisco, and State ol' Gali- 118, 1862, and for improvementsthereon July 7, 1863.

signed to render the valve of simpler and cheaper con` struction, and more effective in operation.

`has been closedby the inside lap on the valve, thereby `piston is suddenly driven againstthe air or water, which may be inthe cylinder.

`j `sive friction `on its face, and permit it to be moved lwithsmall expenditure of power'. i

and steam-chest, and is operated by similar mechanthe `main port is closed on the exhaust side, I provide `valve, midway between the exhanstcavity and the ,i 1 uitrit tant ANDREW J. s'rnvnNs, or `SAN FRANCISCO, CALIFORNIA.

' Letters Patent No. 100,814, dated March. 15,1870; (rn'tella'ted Mai-0h45, 1870.

-my w- 1 IMPRovEt/mivr IN STEAM-ENGINE: SLIDE-VALVES."

The Schedule referred to in these LettersrPatent and making part cf the same.

ll'o `all whom it mag/concern:

Be it known thatI, ANDREW J; STEvnNs'of the fornia, i have invented certain new Improvements in my so-called Anti-Coriipression and Balanced Slide- Valve and II d0 hereby declare that the following is a full, clear, and exact description of" the saine, reference being had to the accompanying drawings and let ters' of reference marked thereon, making a part of this specilication, in which- Figure 1 is a side view,

z Figure 2 is a cross-section,

Figure 3 is an under-side view, and

Figure 4 is a pla'u or top view ofthe valve.

This invention consists in certain additional Y improvements iny the construction and operation of my anti-compression and balanced slide-valve, for which Letters Patent were granted to me, bearing date June The additionalI iniprovements I now make are dei First, to release the steam,V which may bc in the cylinder on the exhaust side, after the exhanst-port preventing compression by theadvaneing piston.

Second, to relievevthe pressure occurring when the i Third, to partially protect the valve from the pressure of steam on its back, thus to relieve it trom-,exces- 'Io enabl'eotliers skilled in the'art to make and use my invention I will proceed to describe it as follows:

The main principles of my valve have been described in the previous LettersPatent granted to me,but to make my description of the improved parts clearly understood, I will here describe the valve complete, and afterward designate what is new and improved.

Myvalvle is in part constructedlike the common slidelvalve,'having same relations to the cylinder ports ism,' bnt is further provided as follows:

'Io release the steam remaining in the cylinder when steam passage-ways A A leadingfrom the face of the edge, to the back of thevalve, where vthey will open into the compartments B B in `the anti-compression steam-chamberG. (See iig. 2.) l y Within these compartments BB are provided the dat valves D D', which alternately open and close a communication with ythe cent-ral passagewayE,)vl1irh may either lead to the main exhaust, as shownin dotted lines, iig. 2, or directly to the atmosphere, as shown in same figure. f

The valvesD `D are held apart by the stems F F', which are a trifle longer than the distance between the seats of the valves they divide; thus, when one valve is driven to, the opposite valve will be pushed from its seat, and one or other of the steam-passages .will be always open.

The anti-'compression valve-chamber Otis secured to the back of the main. valve vby the-bolts G G', las

shown in igs. 2 and 4,

The stems F F are not solid with the valves,` but set loosely between them, and are inserted in their positions through holes drilled in the side of the chamber in which they set, which holes are afterward plugged up by the plugs H H.

The action of this part of my valve is as follows: When, during the operation of the engine, the main exhaust-passageis closed, and the steam in the cylinder on the exhausting side lhas not all escaped, compression of the remaining steam, by the advancing piston is avoided, by reason ofthe expanding steam on the steam side closing its own anti-compression valve, and opening the one corresponding vto the exhausting side, thus a'free exit is provided forthe unexhausted steam through, the auxiliary exhausting passages, which connect the main ports in the cylinder with either the exhaust-port or the atmosphere.

Thenext part of my invention-is the provision made for preventing a pressure which would be caused by the piston suddenly striking air or water, which might bein the cylinder. y

lhis is accomplished by what I call the relief. valves I I in connection with the steam-passagesA K K'. These steamepassages K K are simply branches from the anti-compression passages A A'. They are made to lead to the back of the main valve and into the steam-space. v Y Y t The valves I I', which open and close these steampassages K K', are conned in the cages L L', which are cast on thefollower M. They are kept to their seats by the pressure of the steam in the steamechest. There may be holes l drilled through the `tops of' these cages, to insure the steam getting at the valve,

if from any cause steam shouldbe prevented from getfiat pieces of metal,

ing steam in the other end of the cylinder. Now, since the anti-compression valve is' only kept open by this steam pressure in the opposite end of the cylinder, then it must be closed when au excessive pressure shall occur in opposition to it. This will often happen when the piston drives suddenly against the air or water which may be in the cylinder. At t-his time, my relief-valve will come into' use, for this excessive pressure, when greater than the steam pressure which keeps the valve seated, will raise it up from its seat, open the passage-way, and permit the air or water to escape into the steam-chest.

With this device, it will be seen that at no time can the pressure in the cylinder exceed that due to the actual steam pressure.

The last part of my invention is the arrangement for counter-balancing my valve, and inclosing acornmnnication lwith vthe atmosphere for the escaping steam from the miti-compressionchamber. This consists as follows:

On the top ofthe main valve, I provide the rim N, which extends around the valve inside of the reliefports'. It is of proportionate height and thickness of metal, as shown in drawing.

Mis a follower, which slips over this rim N down to about a distance as shown in fig. 2.

Tile upper'end of this follower terminates in a broad flange, P, which bears against the faced surface of the steam-chest cover. 4

I make the joint between the rim N and the follower M steam-tight, by casting in the angular groove or cavity, which extends around the top of the rim N, a ring, R, of soft expansible metal, as type metal. This ring R will be wedge-shaped, with its thin edge set upward, as shown in iig. 2. This ring may be cast with the follower in its place;

One or more elliptic springs S, having their ends inserted into cavities T in the follower M, and bearing inthe center upon the back of the anti-compression valve-chamber, will serve to keep the follower against the surface of the steam-chest cover, when no steam is in the steam-chest.

There will be two cages L L', as before described, cast on the follower, to inclose the relief-valves I I.

This follower M operates to exclude the steam from the back of the valve, and thus protects the valve in ameasure from the steam pressure, which would otherwise create a great amount of friction on the valveface, which would cause a great expenditure of power in operating.

The steam acting against the base of the metal' ring It will wedge it upward and outward tightly against the inside of the follower, and thus insure a steamtight joint.

The pipe which leads from tbe top of the steamchest cover may either lead to the main exhaust-pipe or elsewhere, as desired, or there need only be an opening left in the steam-chest cover. v

The parts of this invention which are additional improvements on my previously-patented valve, and which I desire to have secured to me by Letters Patent of the United States, I will here designate and claim as of my invention as follows: y

1. The improved anti-compression valves D D', being simply long flatv pieces of iron or other metal, in combination with their valve-seats andthe stems F F', for the purposes as set forth, andconstrueted in the manner substantially as described.

2. The relief-valves I I', in combination ywith their respective cages and steam-passages K K', for the purposes as set forth, and constructed and arranged in the manner substantially as described.

3. The wedge-shapedmetal ring It, placed inthe cavity around the top of the rim N, for the purposes as set forth, and constructed and arranged in the manner substantially as described.'

ANDREW J. STEVENS.

Witnesses GEORGE PARDY, JAMES L. DRUM.

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