US89103A - Improvement in steam-engine valve-gearing - Google Patents

Description

, 2 Sheets-Sheet 1.

A. WHITTEMORE.

Steam Engine Valve Gearing.

Patnted April 30,1869.

Win/eases:

. 2 ShBGtST-ShGBt 2. A. WHITTEMORE. Steam Engine Valve Gearing.

Patented April 30, 1869.

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W ttuitexl AMOS WHITTE MORE, OF vCAMBRI DGEPORT, MASSACHUSETTS.

Letters Patent No. 89,103, dated April 20, 1869.

IMPROVEMENT IN STEAM-ENGINE VALVE-GEARING.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern Be it. known that I, AMOSWHITTEMORE, of 0ambridgeport, in the county of Middlesex, and State of Massachusetts, have invented certain new and useful Improvements in Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, making a part of this specification, in which- Figure 1, sheet 1, is a perspective View of my improved engine complete, showing the segment of the variable eccentric fully expanded.

Figure 2 sheet 1, is an elevation of one end of the engine with a portion of the piston and valve-chests broken away to show the tapering portion of the driving-shaft and its journal-box.

Figure 3, sheet 1, is modification of the variable eccentric shown in figs. 1 and 2.

Figure 4, sheet 2, is a plan view of the mechanism for regulating the movements of the slide valve, and a sect-ion taken horizontallythrough the piston and valve-chests.

Figure 5, sheet 2, is an elevation of one side of the engine and its appendages.

Figure 6, sheet 2, is a view in detail, showing the manner of packing the rectangular piston.

Figure 7, sheet 2, is an enlarged view of the variable eccentric and expanding-wedge, shown in figs. 1, 2, 4, and 5.

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

This invention relates to certain novel improvements on steam-engines, and consists mainly in so applying an expansible eccentric, which is controlled by the regulator, or governor of the engine, to mechanism .for moving the slide valve, that more or less steam will be admitted from the steam-chest into the piston-chest, according to the amount of work which the engine is doing, as will be hereinafter explained; also, in a'novel construction of the steam-chest and piston-chest, so as to adapt them for a rectangular piston also in the pro-- vision for packing the shaft, which receives motion directly froma piston working at right angles to it; and also in providing for contracting the size of the slot in the rectangular piston,,so as to have the slide or block on the wrist-pin ofthe driving-shaft crank, always work truly in said slot, all of which will be hereinafter explained.

To enable others skilled in the art to understand my invention, I will describe its construction and opera tion.

In the accompanying drawings I have represented a rectangular piston, P, which may be made of any suitable length, width, and thickness, applied withina chamber of corresponding width and thickness, but of greater length, which chamber is formed in the rect angular chest A, as shown in figs. 2 and 4.

This chest is constructed with its upper and lower sides formed on it, and with the ends ac, and one side removable, so that the inner. faces of the chest can be planed true.

On the back of this piston-chest is avalve-chest, B, one side and two ends of which are removable.

Within this valve-chest slides a long D-valve, V, for regulating or cutting off theentrance of steam through the ports n a, leading into the piston-chest, as shown in fig. 4.

This valve 'V has passages t t leading from points near its cnds, to a common exhaust-port, r, and to one end of this valve a rod, H, is suitably applied, which passes through a stufiing-box, G, applied at one end of the valve-chest, and is connected by nuts f, or otherwise, to the right angular arm f of a reciprocating rod, F.

This rod F is arranged in a horizontal plane, and slides in guide bearings b 1), outside of the valve-chest B, as shown in figs. 1, 4, and 5, and to this rod ayoke, F, is secured at its ends, for the purpose of atfording bearings a a, for two anti-friction wheels E E, which are of equal diameter.

Instead of the yoke F, upright supports may be formed on or secured to the rod F, to aflord bearings for the studs u u, on which turn the wheels E E.

The wheels are used to avoid friction merely, and toes may be adopted in their stead.

Between the two anti-friction wheels E E, and keyed upon the driving-shaft D, is my improved eccentric, consisting of two segments 0 and c, which make a perfeet circle when expanded, as indicated in figs. 5 and 7, and give the greatest amount of throw to the rod F, and its valve V, but when contracted, as indicated in fig. 7 in dotted lines, will give the least amount of throw to said parts.

The segment 0 is pivoted to segment 0, at c and also loosely attached at or near its free end to segment 0, by means of a link, 2, shown in figs. 4 and 7, and between the two segments, and guided by a groove made in the largest segment 0, is a tapering expander, or wedge, g, which is applied to a circumferentially grooved hub, J, placed loosely upon the driving-shaft D, so as to turn therewith, and at the same time be allowed to receive endwise movement.

Two anti-friction rollers k k, are applied in the annular groove in hub J, which rollers are on the ends of a yoke or bifurcated arm, K, that is connected to a rock-shaft, L.

This shaft L is supported by suitable bearings upon the foundation of the engine, and is connected by means of an arm and swivel-joint to the stem m of the governor. V

N is the governor-spindle; N, its grooved-pulley;

and p p, the arms to which the balls 0 are applied. This may be the old and well-known form of governor, or any of the improved forms of steam-engine governors, or regulators, adapted to the purpose, may be adopted.

The governer-spindle will receive motion from the shaft D, by means of pulleys and belts, or in any other suitable manner.

By the expansion and contraction of the governorballs, the hub J will be moved endwise upon its shaft D, and by thus moving the said hub, the wedge I which is applied to it, will cause the expansion or contraction of the eccentric G c.

For instance, when the engine is running at full speed, and the balls of the governor are expanded to their fullest extent, the hub J with its wedge y, will be moved back so far that the wedge will allow segment cto assume the position with respect to the segment 0, indicated in dotted lines fig. 7, and give the least amount of throw to the valve V, thus allow W ing the ports to be opened to their least extent by the valve V.

On the other hand, when the balls of the governor descend by a diminution -of the speed of the shaft D, the hub J will be moved toward the expansible eccentric a certain distance, varying with the speed or work of the engine, and the wedge y will cause an expansion of this eccentric, which will consequently give a greater throw to the valve V, and a proportionate increase in the opening of the ports n n.

The driving-shaft D is constructed with a tapering portion, (1, upon that portion of it which passes through the frame above the valve-chest, surrounding which, tapering portion, is a divided, or section journal-box, e, which may be set up when desired, so as to makea perfectly tight joint, and a firm bearing around said shaft at the point, as shown in fig. 2.

On that end of the shaft D which passes through I the journal-box e, a crank-arm, or disk, R, is keyed,

from which a cylindrical stud, W, extends, that receives loosely upon it, a rectangular block, T, that slides freely in a groove made vertically in one side of the piston l, as indicated in figs. 4 and 6.

Directly beneath the end of shaft D, a recess, 'i, shown in dotted lines in fig. 6, is made in the bottom side of the piston-chest A, inside thereof, for receiving oil, into which the block '1 dips once in every revolution of shaft 1), thereby carrying up oil, and lubricating the parts which are exposed to wear.

One side T of the slot in which works the block T, is adjustable for the purpose of being set up when necessary, to compensate for the wearing of this block and the sides of its slot.

This adjustment of the side piece T, is effected by means of set-screws 3 3', tapped into one end of the piston, and abutting against the ends of rods 4 4, which receive upon them, and keep in place said adjustable piece '1. This arrangement is shown in fig. 6 in dotted lines.

The piston I? may be packed by means of strips h h, acted upon by springs, or in any other suitable manner, which will prevent steam from escaping between its sides and the walls of the piston-chamber.

I prefer to adopt the arrangement of the packingstrips shown in fig. 6, which consists in having the strips It It break joints at their ends.

The operation is as follows:

Steam is admitted freely into the valve-chest B, through steam-pipe B, and alternately enters the piston-chamber through ports a a.

\Ve will suppose the piston P is at the terminationof a stroke, when steam is admitted into its chamber and the expansible eccentric is adjusted to give short strokes.

The valve V will be moved in the same direction as the piston is moved, until the piston reaches about, say one-third of its stroke, when said valve will remain stationary at full head of steam, until the piston has moved about three-quarters of its stroke, when it will tion reaches the termination of its stroke.

During this operation, the port a opposite to that receiving steam, will be opened to allow of the exhaust.

The same operation takes place when the piston makes the next stroke. A

\Vhen the engine is working with the eccentric fully contracted, the valve V receives the shortest strokes, andconsequently the least amount of steam will be admitted into the piston, and the governor-balls will be expanded to their fullest extent. f-

As the speed of the engine-shaft 'D is diminished, and the governor-balls descend, the wedge 9 will be forced between the segments 0 c, and the throw of the valve V will be more or less increased, thus increasing the supply of steam to the piston-chamber by increasing the capacity of the ports a.

By these means, I have an automatic and a'perfect regulator of the amount of steam required to work the piston, which will vary to a nicety, according to the amount of work required of the engine.

I have shown my improved expansible eccentric and its connections with the slide valve V, adapted for a very compact and cheap engine, where the drivingshaft D is arranged at right angles to the piston P, but it is obvious that the said eccentric is applicable to almost any of the well-known slide valves, .by employin g suitable connections, substantially as described, between the eccentric and valve, and the eccentric and governor.

In fig. 3, I have represented modification of the expansible eccentric above described, which shows a segment, 0', pivoted to the segment 0', at a point further from the axis of its shaft 1), than the pivotal connec-. tion 0 of the segment 0, is from its shaft D.

This eccentric will close the valve sooner, other things being equal, than the one previously described, and therefore work steam expansively a greater part of the entire strokes of the piston.

Having described my invention,

What I claim as new, and desire to secure by Letters Patent, is y 1. Thevariable eccentric O c, and expander y, controlled by a governor, and operating to regulate the movements of the slide valve, substantially as described.

2. The expansible eccentric O c, in combination with a hub, J, carryinga wedge, g, said parts being applied upon the driving-shaft D, and controlled by a governor, substantially as described.

3. Shaft D, arranged at right angles to the piston P, and receiving motion directly from the piston, in combination with slide valve. V, rod H, stuifing-box G, rod F, yoke F, rollers E, and an expansible eccentric O c, all being arranged to operate substantially as described.

A, constructed as herein described, and having a shaft motion directly from the piston P, substantially as described.

5. The construction of the rectangular piston P, with a slot in one side of it, for receiving the swivel block T, on the crank of the driving-shaft D, in combination with the adjustable piece T, substantially as described. 7

AMOS WHITTEMORE.

Witnesses:

JULIUS Hrnscn, R. T. CAMPBELL.

begin to close slowly, and is fully closed before the pisp 4. The valve-chest B, and rectangular piston-chest D, arranged at right angles to them, and receiving

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