US15025A - Operating valves oe steam-engines - Google Patents

Description

3 Sh t-sn 0. TUFTS. 68,8 eet 3 Steam Engine Valve Gear.

No. 15.025. Patented June 3, 1856.

UNITED STATES OTIS TUFTS,

OF BOSTON,

MASSACHUSETTS.

OPERATING VALVES 0F STEAM-ENGINES.

Specification of Letters Patent To all whom t may concern:

Be it known that I, O'rrs TUFTs, of Boston, Suffolk county, Massachusetts, have invented a new and useful Method of Working the Cut-Oft' Valve, Separate or United with the Exhaust-Valve, in Steam-Engines; and I hereby declare that the following description, with the accompanying drawings, forms a full, clear, and exact specification thereof.

Figure l is a side view of the steam cylinder with my improvement applied, one end in section to show the piston, and also the cut-off and exhaust valves united. Fig. 2 is an end View of the same. Figs. 3, 4, 5, 6, 7, 8, 9, l0, l1, exhibit the mechanism in detail, to be explained.

I use a thick circular plate (a) placed upon a strong pin (o) projecting from the engine frame or bed plate. Said plate receives an oscillating motion from an eccentric or its equivalent. That side of the plate which is nearest the engine frame I call the inside, and its opposite the outside. Fixed in this plate in suitable positions from its center, and projecting perpendicularly on both sides are pins (c) on which, cams (d) are adjusted to operate the cut off valves (e). As these cams and their attachments are alike, a description of one will be sufiicient. The circular or front edge (f) of said cam, which communicates motion to the valve, is concentric to the pin on which the cam turns for adjustment, and is always in position to open the valve uniformly and at the right time; while the nearly straight or back edge (s) of said cam which governs the closing of the cut o valve, changes its position as required to cut oft1 variably. This cam is placed on the inside of the plate, and turns on the end of the pin projection from that side. A piece (it) somewhat similar in form to the cam, is placed on the outside of the plate, and turns on the end of the pin projecting from that side; it has a long hub for increased bearng on the pin, and is united with the cam on the inside by strong studs (i) passing through an opening in the plate, so that in eect, the two are as one piece turning on the same pin. The adjustment of the cam for cutting o variably is effected as hereafter described by a rod acting on a pin fixed on the said outside piece. On the back edge of said cam, which governs the closing of the cut ofin valve, I

No. 15,025, dated June 3, 1856.

use an adjustable sliding arrester (j) grooved on or otherwise suitably attached for the purpose of arresting the motion of the valve and its gear, just after closing, in such manner as to prevent ar and unnecessary wear of the parts; this arrester is connected at its inner end with one arm of the toggle joint, (is), the other arm of said joint being connected with the inner end of the cam, and the joint moving against the curved recess (Z) in the plate-said joint being held to the curved face of said recess by an adjustable coiled spring and presser arm (m) fixed in the back part of the outer and of the cam, and pressing against the outer point of the sliding arrester, so that as the cam turns upon its pin to vary the cut off the arrester slides out or in on the back edge of the cam to adjust itself in position for easing off the motion of the valve and its gear as aforesaid.

On the same side of the plate with the cam, is fixed an inclined plane (n) suitably sloped to give the sliding cam roll (o) an inward lateral movement as it leaves the back edge of the cam, and even with the top of this plane is fixed a thin steel sheet (p) which extends over the cams, and covers all that portion of the plate not required by the acting surfaces of the cams and planes-so that the sliding roll, when the cam has left it, passes on and bears its rounded end (g) against the steel sheet, until the cam returns to the position required to open the cut off valve, when the roll passes off from the steel sheet, over a slight extension of its edge and is thrown outward by an internal spring to its position to be again acted upon by the cam. Said sliding roll is made to slide and turn in a long bearing (o) in the end of one part of the curved double arm (s), and on an internal pin (t) fixed in the end of the other part of said arm, said sliding roll having a suitable interior spring acting against the interior end of said pin. The two parts of said arm are firmly united by the shaft (u) to which they are fastened and with which they swing, and also by the connecting pin (o) which through the rod (fw) and the crank and valve stem imparts motion to the cut off and exhaust valve united. I use strong adjustable coiled springs (a) which act through the lever (l) and the rod (2) upon t-he connect-ing pin uniting the two parts of said curved arm, and force the rolls against the acting edges of the cams by which the valves receive motions due to the forms of the cams ;-the force of the springs closing the steam and opening the exhaust ports.

On the same main pin with the thick plate I place an exhaust cam which receives an oscillating motion from another eccentric or its v equivalent properly adn justed. This cam being double, and so shaped on its working edges and adjusted on said main pin as to work the exhaust valve in proper time, acts upon a roll (4) that turns on the pin fixed in the end of one part of said double arm, and opposite said sliding roll. Said double arm consisting of two parts firmly united as described, is a rigid device, carrying said two rolls to be acted on alternately by the steam, and exhaust cams. rlhe circular or holding edge of the exhaust cam, is depressed or drawn in a little toward its axis, from the point where it meets the nearby straight edge, so that its roll shall not come in contact with it, until the arrester on the cut off cam has performed its ofhce on the sliding roll in easing off the motion of the cutoff valve and its gear.

)When the steam and exhaust valves are not united in one and operated as above described, but the exhaust valve is separate and operated independently, the sliding roll is not allowed to pass on and bear its end against the steel sheet, after receiving an inward lateral movement from the inclined. plane, but is held against the force of said coiled springs (e) by a rim or cam (5) having the same form and adjustment as the circular edge of said exhaust cam, and applied to said steel sheet, and against the force of said interior spring, by a double catch (6) suitably fastened upon a pin passing through the two parts of the double arm, and is released by a pin (7) projecting from the plate and lifting the catch in time for the roll to be thrown out in position to be acted upon by the cam as before described.

The adjustment of the cams for cutting off steam variably, is effected by a screw turned either by hand or a regulator. The screw (8) is placed at a suitable distance from the outside of the thick plate on a line parallel to its face and radiating from its axis; and turns in bearings (9) at each end, held between two guides (10) placed parallel to the axis of the screw, and supported from the plate; the out-side guide terminates .in a ring (11) about the center of the plate and forms a tie to the pins on which the cut off cams move.

There is a sliding carrier (12) movable along the guides which carries a cylindrical nut (13) adapted to receive the screw; the nut passes through the carrier and can,

turn in it, but is kept from moving endwise when brought up at either end against the stop collars of the screw, by a flange (14) at each end; inside the carrier are friction clamps (15) made adjustable by right and left hand screws (16) and surrounding coil springs (17) arranged so as to bind the nut with pressure friction, and keep it from turning, within any desirable limit of power; one of said screws having on its end a small binding nut (18) and being turned by the movement of the other for adjust-ment, through the intermediate gear (19); on two sides of the carrier are projecting ears (20) through which pins (21) pass and serve, by connecting rods (22) to communicate the motion of the carrier to the pins fixed in the outside pieces of the cut off cams for their adjustment by the movement of the governor, or other regulator.

It will be observed that all attachments to the thick plate must partake of its oscillating motion; while the regulator shaft (24) can only turn in stationary bearings; in order therefore to maintain a connection between the screw and the regulator shaft, I place on the end of the pin that supports the plate a bevel gear (25) free to turn either way, and meshing with it and lfastened on the end of the screw is a similar gear (26), and in like manner, on the end of the regulator shaft is another similar gear (27) so that the plate and its at-A tachments including the screw oscillate about its center without affecting the regulator shaft any further than to impart to it a slight oscillation about its own axis which is prevented from continuing throughout its length, by making it in two parts, and forming a connect-ion between said parts by a coupling (28) withvclutches having suiiicient space between them to allow the oscillation of one part without the other.

Power applied to turn the regulator or hand shaft is transmitted through the gears to the screw, which acting in the nut moves the carrier upon the guides until it reaches the end of the screw, when if the power be continued in the same direction, the nutv will turn with the screw, overcoming the friction of the clamps.

The arrangement of the aforesaid strong coiled springs is the same for each valve, as follows; a semicylindrical box (29) is attached by one end to the engine frame, and in the center of each end a bearing is provided for a shaft (30) which occupies the center Vof the box; on the middle of the shaft said lever (1) is fastened to impart the power of the springs as before described; also on the shaft near each end between the.

lever and the bearings, are placed ratchet wheels (31) free to turn in one direction on the shaft, but prevented from returning by the pawls which lare attached to the box, and catch in their teeth; the springs, one coiled from right to left, the other from left to right, occupy the spaces between, and are attached to the lever and the ratchet wheels, and are brought to the required tension by t-urning said wheels. A cover is neatly fitted to the box inclosing all parts except the lever, and having the external appearance of a simple cylinder. vWeights may be used instead of springs when more convenient.

l/Vhile my invent-ion admits the application of any kind of governor commonly applied to regulate steam engine, l prefer to use the one employed to regulate the speed of water wheels, and known as the clutch gear iiy ball governor, in which a variation of speed will cause a shaft to turn to the right or left as required. I am thus en# abled to cut off the steam variably in adjustment with the work of the engine, and by dispensing with the throttle valve, to work the steam upon the piston at nearly its full pressure in the boiler; and to simplify the valves in number and operation and effect a saving in fuel.

All the figures are drawn on a quarter scale except Figs. 5, 8, 9, which are drawn on a half scale to exhibit more distinctly the arrester and its parts and the sliding nut carrier and its parts. The scale may be varied as required.

I claim l. The oscillating plate with its attachments, carrying the adjustable cut off cams acting with their sliding rolls for cutting off the steam variably, substantially as described.

2. The self adjusting arrester and its part-s acting on the closing edge of the adjustable cut oif cam for easing off the motion of the cut off valve and its gear, substantially as described.l

3. The adjusted arrangement in combination, of the cut olf and exhaust cams, to work the cut olf and exhaust valves united, substantially as described.

4. The double arm with its sliding and other roll, acting alternately on the cut ofl, and exhaust cams substantially as described.

5. The gear joint connection between the regulator shaft and the adjusting screw, for working them together while one is fixed and the other oscillates, substantially as described.

6. The sliding carrier with its attachments and friction held nut, for adjusting the variable cut off cams on the oscillating plate, by the regulator, substantially as described.

7. The arrangement of the adjust-able coil springs in combination with their shaft and lever for forcing the rolls to the cams substantially as described.

OTIS TUFTS.

Vitnesses:

W. H. Hicks, J. GILEs.

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