GB190004257A - Improvements in and relating to Steam Engines. - Google Patents

Abstract

4257. Whitfield, M. L. March 6. Engines with reciprocating cylinders; cycles or systems of working; valves and valve gear.-Relates to engines of the type in which a reciprocating piston-cylinder works within a stationary cylinder and over a stationary piston-abutment, and consists of means for enabling such engines to be worked either compound or simple, and to be reversed. The invention is especially suitable for marine engines and locomotives; it is illustrated in the Specification as applied to vertical engines and to horizontal engines. Fig. 2 shows a vertical section of one form, and Fig. 3 shows a part section at right-angles to that shown in Fig. 2. In these c is the stationary cylinder, d, e the reciprocating piston-cylinder provided with a crosshead 6 to which the connecting-rod 7 is attached, and g the stationary piston supported by the abutment f, which is bifurcated so as to clear the crosshead and connecting- rod. The main distributing- valve l works in a casing k supplied with live steam by the branch 42 and communicating with the interior of the reciprocating cylinder by passages 3 in the bifurcated abutment f. There is an oscillating exhaust valve h lodged in a casing forming the upper cylinder cover, and an intermediate valve i lodged in the piston e and made to oscillate with the valve h by means of the splined spindle 13. The main valve l is worked through arms m on a rocking shaft by a double-eccentric link - motion, and from the main valve the movement is transmitted to the exhaust valve through suitable linkage and thence to the intermediate valve. The main valve l is in the form of a sleeve closed at the ends by piston heads. It has three sets of ports, one much larger than the others, working over three sets of ports in the valve-chest liner, and its action depends upon the extent of its travel. With limited travel the working is compound ; steam is admitted to the piston-cylinder to effect the up-stroke, the exhaust valve h being open, and at the completion of the stroke the exhaust valve is closed and the intermediate valve i is opened, thereby allowing the steam to expand from one cylinder into the other during the downstroke, on the completion of which the same action is repeated. With increasing travel the cut-off becomes later, and at a certain point steam begins to be admitted to the large cylinder during the down-stroke ; with full travel of the valve simple working is established. The link-motion enables all these changes to be effected by an ordinary reversing-lever, and also enables the engine to be easily reversed.