US137167A - Improvement in reciprocating steam-engines - Google Patents

Description

ZSheets- -Shet. A. E. BAKER.

Reciprocating Steam-Engines.

No. 137,167, v PatentedMarch25,1873.

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Reciprocating Steam-Engines. No. 137,167. Patented March25, 1e73,

INVENTDR w/wf/wy AM. Pnora-umoaRAPH/c ca. MMJsBD/ms moons) UNITED STATES PATENT OFFICE.

AUGUSTUS E. BAKER, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR TO HENRY W. GARDNER, OF SAME PLACE.

IMPROVEMENT IN RECIPROCATING STEAM-ENGINES.

Specification forming part of Letters Patent No. 137,167, dated' March 25, 1873.

To all whom it may concern:

Be it known that I, AUGUSTUS E. BAKER, of the city and county of Providence, in the State of Rhode Island, have invented certain new and useful Improvements in Steam-Engines; and I do hereby declare that the following specification, taken in connection with the drawing making a part of the same, is a full, clear, and exact description thereof. Two sheets of drawing are presented, of which- Figure l is a side elevation. Fig. 2 isa longitudinal and vertical section through the cylinder, steam-chest, and exhaust-passages. Figs. 3, at, 5 show the construction of the air dash-pot used to arrest the movement of the valves in closing. Fig. 6 represents on an enlarged scale the cylinder in longitudinal vertical section.

The improvements hereinafter described are particularly applicable to a steam-engineorganized on the plan shown in the Letters Patent granted to Noble T. Greene under date of March 13, 1855. In the machine of the said Greene referred to the steam-valves are opened by means of tappet-s mounted on a sliding bar, which latter is worked by an eccentric on the main shaft. Each tappet is in combination with an arm keyed to a shaft with which the valve is linked, which arm, by the movement of the tappet as the sliding bar is worked, is vibrated through the arc of a circle sufficient to open the steanrport but the extent of movement of the tappet in a straight line is such that the face of the tappet and the face of the arm separate their contact, whereupon the valve is allowed to close by means of a weight or spring. To give a quick initial movement to the steam-valves in closing by making use of a steam-pressure to assist this closing movement is one object of my invention.

In the drawing, A represents the cylinder of the en gino, and'B the piston. The two steamvalves are located at the ends of the cylinders in the chests O O. In this instance the valves are of the variety known as gridiron slides, and are so set that their steam-ports are covered by the movement of the respective valves in the direction toward the opposite end ofthe cylinder. The valves F are furnished with rods a, which pass through stuffing-boxes 6.

Their outer ends are slotted to receive tappets c, Fig. 2, which latter are keyed, respectively, to the transverse shafts d, upon the ends of which are the arms c, Fig. 1, with which the tappets f on the sliding bar D engage for working the valves, substantially as shown and described in the Letters Patent of the said Noble T. Greene, with the difference that the valves in this instance, in closing, move in the opposite direction to that in which they are shown to move in the said patent.

In order to give a quick initial movement to the valve in closing I make that part" of the valve-rods a which comes inside the steamchests of so great diameter as to cause a sea sible difference in the steam-pressure exerted upon the two ends of the valve. This excess of pressure applied in the direction in which the valves move in closing causes the valves to cover their ports upon the instant that they are released from the control of the valve-gear.

It is well known that there is in all steamengines employing flat sliding valves and valve-rods passing through stuffing-boxes in the steam-chest a greater degree of steampressure exerted upon the end of such valves opposite to the end at which the valve-rod is connected, but such excess of pressure can be made practically useful for assisting the closing movements of the valves only when a libcrating valve-gear is employed, and under an arrangement which enables the valves in 010s ing to move in the direction of the stuffingboxes in the valve-chests.

A further improvement consists in the means employed for operating the exhaust-valves, whereby the valve at that end of the cylinder at which the steam is exhausting is permitted to remain wide open until the steam-valve at that end is ready to open.

The two exhaust-valves g g, Fig. 2, located, respectively, at each end of the cylinder, are connected by the rod m midway between the ends thereof is a projecting lug, h. E is a twoarm wiper attached to a shaft, k, and which vibrates by means of an eccentric on the main shaft. The lug it above mentioned stands in the space between the two arms of the wiper E, which arms radiate from the rocker-shaft k. The inner face ofone of these walls acts to throw the valve open at the proper time, and obviously the valve so opened will remain in the position in which it was left until the arm h is acted upon by the inner face of the other wall of the wiper to effect the return movement, and thus a free exhaust-passage can be made to exist during the entire movement of the piston for each stroke.

A further improvement resides in the arrangement for giving easy access to the exhaust-valves.

At each end of the cylinder the clearances G G are made large, and these connect with a large exhaustchamber, H, made in the bed. From this chamber leads the exhaust-pipe 1. The cubical capacity of the chamber H is intended to be as large as the cylinder. The exhaust valves g g and their seats are located at the entrance of the chamber H at each end, and at the bottom of the clearance-passages G G, as seen at Fig. 2, by which arrangement, upon removing the cylinder-heads, the exhkalust-valves and their seats are easily access- 1 e.

In this class of engines having liberating valve-gear and detachable valves it is necessary to employ a means for arresting the movement of the steam-valves in closing. In Figs. 3 and 4 is shown the means for forming an air-cushion for this purpose commonly employed. I have, however, improved this device by combining with the weighted piston J of the air-cylinder a tapering plug, 7c, Fig.

5, which screws into the bottom of the piston,

and can be adjusted therein so as to contract earlier or later, relatively to the time of the closing of the valve, an orifice in the bottom of-the air-cylinder L, into which the conical portion of such plug works, and thus regulate the arresting of the valves movement.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The arrangement of the detachable sliding valves F F, their valve-rods a a, and the valve-gear which operates the valves for their opening movements, substantially as herein described, whereby the excess of steam-pressure on the back ends of the valves may be made available to assist their closing mox'ements, as herein set forth.

2. The combination of the two-arm wiper E on the rocker-shaft k, the two exhaust'valves g g, and their connecting-rod m, substantially as described.

3. The arrangement of the clearance-pas sages G G, the chamber H, the exhaust-valves y g, and the heads of the cylinder, substantial ly as described.

4- The tapering adjustable plug K, in combination with the piston J and air-cylinder L, substantially as described.

AUGUSTUS E. BAKER.

Witnesses:

BENJ. F. THURSTON, EDWIN C. PIERCE.

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