US36941A - Improved slide-valve for steam-engines - Google Patents

Description

UNITED STATES PATENT OEETCE.

ALEXANDER BUCHANAN, OF NEW' YORK, N. Y.

IIVIPROVED SLIDE-VALVE FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 36,94 l. dated November 18, 1862.

To all whom, it may concern:

Be it known that I, ALEXANDER BUCHANAN, of the city, county, and State of New York, have invented a new and useful Improvement in Valves for the Induction and Eduction of Steam to and from the Cylinders of Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this speciiication, in which- Figure l is a plan view of the interior of the steamchest of an engine having my invention applied. Fig. 2 is a central longitudinal vertical section of the steam chest and valve and their appurtenances. Fig. 3 is a transverse vertical section of the same.

Similar letters of reference indicate corresponding parts in all the figures.

This invention relates to that kind of valve which may be termed the oscillating segment7 valve-that is to say, which is constructed with its face in the form of a portion of the periphery of cylinder, and is arranged to oscillate about a fixed axis in a seat of corresponding form.

The improvement consists, principally, in combining the valve with the pendulum or oscillating arm, to which it is attached by meansof a iiexible and elastic plate, which constitutes a portion of the back or" the valve, and which, while it allows the greater portion of the pressure produced by the steam on the back of the valve to be transmitted to a iixed bearing at the axis of oscillation, at the same time permits the valve to be pressed against the seat with suflicient force to counteract the tendency to lift the valve, which is produced by the pressure of the steam in the ports during portions of the stroke of the valve.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

c c is the concave arc-formed valve-seat, having the ports b b c, arranged, as is customary, in the seat ofthe common slide-valve. A, B, C, and D represent the different portions of the valve. The portion A, composed of a single frame-like casting, constitutes the face, ends, and sides of the valve, and contains the exhaust-chamber h, but is made without a top or back, that being formed by the plates B and C. The plate B is made of wrought or cast iron stout enough to insure its perfect rigidity under all the circumstances of the operation, and is of a form corresponding with the upper or back portion of the chamber L, but sufficiently smaller to have a narrow opening between them, as shown at j j in Fig. l, all round the plate. I prefer the form of the said plate and of the back part of the chamber h, in which it is received, to be of oblong form with the ends rounded, as shown in Fig. l, where part of the said plate is exposed to view by breaking away a portion of the plate C above it, and the remainder is shown in dotted outline. The top or cap plate C, made of thin copper, brass, steel, or other flexible and moderately elastic metal, covers the whole of the top of the portion A, and is secured thereto in such manner as to be perfectly steam-tight by the gland D, which is screwed down upon it by screws t t', screwing into A. The rigid plate B, which may be termed the sustaining77 plate, is rmly secured to the thin plate C by riveting or otherwise, to prevent it from bending or springing in anypart which covers the chamber h, except in the part which covers the space j j, between the plate B and frame A, and this part is swaged or otherwise formed with a deep groove on the under side and a corresponding projection on the other side, as shown at k lr, to give it a certain degree of flexibility.

E is a rock-shaft, from which the valve is suspended by the pendulum or vibrating arm I, supported in bearings Z Z in fixed standards F F, supported by a bridge, G, placed across the interior of the valve-chest H. The distance between the axis of the rock-shaft E and the valve-seat is equal to the exact radius of the arc of the faces of the valve and seat. In order to enable the said rock-shaft to be adjusted to bring its axis exactly concentric with the arc of the valveseat, the bearings Z Z should have suitable packing or adjusting plates or pieces applied below them and at their sides. The plates B C of the valve are secured to the lower part of the pendulum or vibrating arm I by means of a gimbal or universal joint p q r, to enable the valve to accommodate itself to the seat in case of any eccentricity occurring between the rock-shaft and the seat. The said pendulum or arm passes through a slot, and the rock-shaft is secured therein by wedges m m, above and below the rockshaft, which enables it to be adjusted to the proper effective length. The valve-chest cover H has an opening provided in it for the standards F F, and this opening is covered by a cap, H2, which is deep enough to admit the yvalve-chest, the connection of the stem and yoke being sueh that the yoke can oscillate -to accommodate itself to the curved movement of the valve.

1 To adj ust the valve for operation, the bearings of the rock-shaft are brought to a position to make its axis concentric with the valveseat, and the pendulum or arm I is so adjusted that the face of the valve may work just in contact with the seat; but the pendulum -may be afterward raised by the wedges m on, or their equivalents, in such manner as to raise the valve slightly from the seat.

Vhen the cover has been applied and secured to the steam-chest, and steam is admit ted thereinto, the pressure of the steam, acting on the whole of the back of the valve, tends to depress the portion A and bring the face in contact with the seat, such depression being permitted by the ilexure of the grooved portion of the plate C; but the elasticity of the said plate prevents any more of such press` ure being transmitted through the face to the seat than is necessary to overcome the backpressure to which those portions of the face .which cover the ports b b are subject while the induction is taking place through them, or after the steam has been cut off from them and before they are brought into communication with the exhaust-chamber h, the remainder of the pressure being transmitted to the bearings Z Z by the sustaining-plate B, pendulum or arm I, and rock-shaft E. The pressure allowed to be transmitted by the valve to the seat is regulated by the setting up' of the pendulum or arm more or less by the Wedges m m or their equivalents.

In order to permit the valve to rise instantly from its seat, as is desirable in case of the sudden reversal of the action of the steam on the piston in a loeomotiveengine, the bearings provided in the ports r r of the universal joint, that are attached directly and rigidly to the plates B C for the reception of the pivots ofthe ring q (l of the said joint, should be left open at the bottom or elongated in a downward direction, or the bearings Z Z should be left open at the top or elongated in an upward direction; or both of these expedients may be resorted to.

This invention may be adapted to an old engine without providing a new steam-chest by securing to the old flat Valve-seat a plate in which the concave or arc-formed seat ce ce is formed, the parts in the seat a a being made to correspond in position with those of the old one. Figs. 2 and 3 illustrate such an adaptation.

In the figures the line e e represents the old seat, and L indicates the plate on which the cone-ave seat a a is formed.

/Vhat I claim as my invention, and desire to secure by Letters Patent, s-

Combining an oscillating segment-valve, A, with the pendulum or Oscillating arm I, which suspends it from fixed bearings by means of a flexible and elastic plate, C, or its equivalent, constituting a portion ofthe back ofthe Valve, substantially as and for the purpose herein specified.

ALEXR. BUCHANAN.

Vitnesses:

J AMEs LAIRD, RICHARDSON GAwLnY.

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