US39125A - Improved valve-chest for steam-engines - Google Patents

Description

UNITED STATES V PATENT CEEICE.

THOMAS S. DAVIS, OF JERSEY CITY, NEW JERSEY.

IMPROVED VALVE-CHEST FOR STEAM-ENGINES.

Specification forming part of Letters Patent No'. 39,125, dated July 7, 1863.

To all whom it may concern:

Be it known that l', THOMAS S. DAvTs, of Jersey City, in the county of Hudson and State of N ew Jersey, havenventedanew and useful Improvement in the Valve-Chests of Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description ofthe same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a centrallongitudinalsection of a valve-chest constructed according to my invention. Fig. 2 is a transverse section of the same in the line x x of Fig. l. Fig. 3 is a gansverse section of the same in the line 3/ y,

ig. l.

The main obstacle which has heretofore presented itself to the successful use of piston valves for the induction and eduetion of steamengines has been the unequal expansion ofthe cylindrical bearings or seats in which such valves work, which has caused the valves either to bind during a portion or portions of their stroke or else too t too loosely durin g another portion or portions thereof, and I believe that but for this diiiculty such valves, owing to the simple manner in which they can be balanced,77 would have been more generally adopted.

The object of my invention is to provide for the equal expansion of the cylindrical bearing or seat throughout its lwhole length; and to this end it consists in a certain arrangement of a steam-jacket surrounding or partly surrounding the whole length of the bearing or seat and communicating with both ends thereof in such manner that the steam will heat the said bearing or seat equally throughout its whole length.

To enable others skilled in the art to construct and apply my invention, I will proceed to describe it.

The valve-chest is composed of an outer casing, A, and an inner cylinder, B, to which the two piston-valves C G are fitted, the said cylinder being openat its ends and so arranged within and being so much shorter t-han the said casing that the space a between them forms a steam-jacket, which not only nearly surrounds the sides of the cylinder, as shown in Fig. 3,

but is open to the ends thereof, as shown in Fig. 1.

The casing may be so constructed that the steam jacket or space a may entirely surround the inner cylinder, except at the ports b b, through which the steam enters and leaves the main cylinder of the engine.

The casing and cylinder may be composed of a single casting or be made of two separate castings and the cylinder secured within the casing in any suitable manner.

The steam-chest thus constructed is secured to the main cylinder by bolts passing through flanges c c, or in any other suitable manner. In the ends ofthe casing there are provided openings opposite to and somewhat larger than the bore of the cylinder B, for the introduction of the piston-valves C G', and these openings are tted with steam-tight bonnets D D', in which there are stuffing-boxes d d, through which works the rod E, to which both of the piston-valves are secured. The openin g j', to which the steam-pipe is connected, communicates with the space or jacket a at any part of its length, and the opening g, to which the exhaust-pipe is connected, communicates with the interior of the cylinder B, be,- -f

tween the piston-valves. Opposite the ports b b there are formed around the interior of the cylinder B grooves e e', which correspond in width with the ports, and which are filled with steam from the ports so that the pistonvalves are balanced on all sides in passing the ports.

The operation is as follows: The steam, en-

tering the jacket or space a, envelops wholly,

or as far as permitted by the construction ot' the casing A, the whole length of the cylinder B from end to end, and as the Valves respectively move inward from their respective ends of the said cylinder the steam enters the said cylinder from the ends and thence enters the ports b b', as they are uncovered by the valves, and as the valves move outward toward their respective ends ofthe cylinders and again uncover the ports, the steam passes out from the main cylinder B, between the Valves, and thence to the exhaustopeningg. It will thus be seen that the entire length of the cylinder B from end to end is heated by the steam and lts expansion from end to end is uniform, or sufficiently for all practical purposes.

What I cla-im as my invention, and desire to secure by Letters Patent, is-

'lhe arrangement of the openended valvecylinder B, within the casing A, in such manner that a steam jacket or space, a, is, formed between them, Which surrounds or nearly surrounds the Whole length of the said cylinder THOMAS s. nAVis.

fitnesses J. W. GooMBS, JONATHAN DAVIS.

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