US16668A - Operating valve of steam-engines - Google Patents

Description

UNITED sTATEs PATENT oEEIoE.

SAMUEL \VILMOT, OF WATERTOW'N, CONNECTICUT.

PEEATG vALvE 0E STEAM-ENGINES.

specification or Letters Patent No. 16,668, dated February 17, 1857.

To :all whom it may concern:

Be it known that I, SAMUEL R. IVUMQT, of lVatertown, in the county of Litchfield and State of Connecticut, formerly of the city, county and State of New York, have invented certain new and useful improvements in steam-engines which are particularly applicable to engines working without cranks, crank-shafts, and fly-wheels, such as are employed for driving saws, pumps, &c.; and I do hereby declare that the following is a full, clear, and exact description of my said invention, reference being had to the accompanying drawings, in which- Figure l represents a side view of a sawing apparatus driven by a direct acting steam engine having my improvements applied thereto, with the valve motion in the proper position when the piston rod is moving inward; Fig.-2 is a view of the position of the traverse rod when the piston rod is moving outward; Fig. 3 is a cross section at the line a' of Fig. l; Fig. 4 is a longitudinal section of a portion of the valvechest showing the throttle valve, and Fig. 5 is a cross section of the same showing the steam passages.

In that class of engines in which the crank is dispensed with, and which are frequent-ly employed for driving saws, pumps, and

blowing engines, it has long been a desid-A eratum to obtain some eliicient means of actuating the valves by a movement derived directly `from the piston rod.

The object of my invention is to eect this purpose in a simple manner, and it consists in a valve motion for actuating the valve or valves, by which the admission of steam to the steam cylinder of a steam engine, and the escape of steam therefrom are elfected and regulated, by a movement derived directly from the mot-ion of the piston rod. This valve motion is composed mainly of a slide and of a traverse rod constructed and combined inV such manner, that during a portion of each stroke of the piston t-he slide ,imparts movement to the traverse rod so as to actuate the valve or valves, while during i another portion of the stroke the traverse rod sets the slide in a proper position to react upon this rod during the succeeding Stroke of` the piston, and during other portions of the stroke neither element of the combination actuates t-he other.

My improvement is represented in the accompanying drawing as attached toa portable sawing apparatus in which the saw A is attached to the crosshead B of a direct acting' engine, whose steam cylinder C is pivoted to a heel block D and whose piston rod extends through a st-utiing box in the head of the steam cylinder and is at-tached to the crosshead B. The butt of the cylinder is secured in a block or base F, in which the steam passages are situated, and which also contains the throttle valve and steam valve; two of these passages terminate in pipes, the one a leading` to the boiler, and the other to the exhaust pipe. The other two passages lead to the steam cylinder, the one j being connected directly with the but-t thereof, and the other Ze with its head through intervention of a side pipe c.

The steam valve in this instance is a fourway cock of the ordinary description, and the steam passages are arranged in such manner that a quarter of a revolution of the cone mI of the valve is required to change the flow of steam and the exhaust from one end of the steam cylinder to the other. The valve stem G is prolonged in a direction parallel with the piston rod and its extremity is pivoted an arm Z that projects from the guide H, which guides the movement of the piston rod. That portion of the valve stem which is opposite the guide and parallel thereto is flattened; it is also twisted at two points f and g, to an extent equal to the angular motion of the cone of the valve` or a quarter of a revolution. This flattened portion of the valve stem forms a traverserod which is traversed by a slide I that is pivoted in an arm 71., which projects from the orosshead B. This slide turns freely in its arm to the extent of a quarter of a revolution, but its movement in either direction beyond this extent is limited by two stops c and z', which alternately strike against the opposite shoulders of the arm h and thus stop the movement or partial revolution ot' the slide.

The stops are arranged in such manner that they permit the slide lto turn upon the twisted portions of the traverse-rod when the slide is moved in either direction from the extremities of the rod toward the middle thereof; and that they will stop the turning of the slide in its arm, and will consequently compel the twisted portion of the traverse rod to turn -in the slide, and turn the cone of the valve, whenever the slide is moved in either direction from the middle of the traverse-rod toward the extremities thereof. If therefore the piston and traverse rod be s et as shown in Fig. l, with the slide in the position in which it is shown in Fig. 3, and the cone of the valve in the position shown in Fig. 5, and if steam be admitted into the cylinder by opening the throttle valve of the engine, the steam entering the cylinder and pressing upon the frontl face of the piston will drive the latter toward the butt of the cylinder. As the piston approaches the end of its stroke the slide passes over the twisted portion f of the traverse rod, which tends to cause the slide to turn upon it in the direc.- tion indicated by the arrow in Fig. 3, but as at this time the stop z' is in contact with the shoulder of the slide arm L, this stop prevents the turning of the slide I, and forces the traverse rod to turn in the slide, in a direction opposite to the arrow in Fig. 3, and thus turn the cone of the valve. This movement of the valve changes the flow of steam from the head of the cylinder to the butt thereof and puts the head of the cylinder in communication with the exhaust pipe. By this change, the steam from the boiler is permitted to act upon the hinder face of the piston and the latter is driven forward in the cylinder; as it moves forward the slide I is carried forward over the same twisted portion f of the traverse-rod, which now tends to turn the slide in the opposite direction to the arrow in Fig. 3. As this tendency is not counteracted by the stops, the slide turns upon the traverse-rod without changingthe position of the latter or that of the valve, and consequently without affecting the iow of steam into the butt of the cylinder' or the exhaust of steam from the head thereof. By the time the slide has been carried upon the straight portion of the traverse-rod extending between the two twisted portions thereof, the other stop e has been brought in contact with the shoulder of the slide arm 7L; so that when the slide is carried over the twisted portion, y, of the traverse-rod, the tendency of thc latter to turn the slide is prevented by this stop; hence the traverse rod is forced to turn in the slide and consequently to reverse the position of the cone of the valve, and change the flow of steam from the butt to the head of the cylinder; while by this same movement of the valve, the butt of the cylinder is put in communication with the exhaust pipe. The change in the flow of the steam is followed by a reversal of the movement of the piston rod during which the slide I passes again over the second twisted portion g of the traverse rod withvout acting upon it; but acts as before upon the first twisted portion f thereof.

From the foregoing it will be seen that when the piston is moving from the center of the stroke toward either end thereof, the slide imparts motion to the traverse-rod to .actuate the valve, because the turning of the slide at these periods by the action of the twisted portion of the traverse rod is prevented by the stops e and When, however, the piston is moving toward the center of the stroke from either end thereof, the stops do not prevent the turning of the slide, which is thus set in a proper position to react upon the traverse rod. And when the slide is traversing the straight portions of the traverse rod, the slide and traverse rod do not act upon each other. As the slide turns the traverse-rod and actuates the valve while the piston is approaching the end of its stroke, the steam is admitted in advance of the piston, and the piston in its onward movement tends to force this steam to flow back to the boiler, or, as is commonly said, the valve has lead given to it. The amount of this lead is controlled by the position of the twisted portion of the traverse rod with respect to the range of motion of the piston. The more nearly their position corresponds with the end of the stroke. the less will be. the lead, and vice versa. Hence it is in the power of the constructor to adopt the lead to the work which the engine has to perform, and to adjust it to the weight and velocity of the piston and its accessories.

In the example I have described, the steam valve is a four-way cock, and the traverserod is connected directly with the steam valve by forming it upon the prolongation of the valve stem. This mode of applying my invention has been selected on account of its simplicity, but it is evident that my invention may be applied to operating steam valves of other descriptions; thus for example it may be made to operate a short slide valve, by connecting the stem of such a valve with an arm secured to the prolongation of the traverse rod; or it may be used in connection with puppet valves by connecting the stems of such valves with arms projecting in opposite directions from the prolongation of the traverse-rod, so that the valvesare raised and dropped alternately. These and other modifications may be made to adapt my improvements to particular circumstances, and I propose to modify my invention as may be necessary to adapt it to the various circumstances under which it may be used.

That I claim as my invention and desire to secure by Letters Patent isw rIlhe valve motion herein described for operating the valves of steam engines and consisting essentially of a twisted t-raverse-rod of a traveling slide, and of the stops which limit the turning of the slide, or their equivalents combined together and operating substantially as herein set forth.

In testimony whereof I have hereunto subscribed my name.

SAMUEL R. WILMOT.

Vitnesses H. S. LINCOLN, F. H. FnN'roN,

Images