GB190008219A - Improvements in Steam Engines - Google Patents

Abstract

8219. Dunlop, P. May 3. Compound and multiple-expansion engines.-Relates to tandem and to parallel cylinder engines such as ensure quick revolution, the nett pressure on the pistons always being in a downward direction. Fig. 1 shows in vertical section the cylinders and valves of a quadruple-expansion tandem engine. Live steam is admitted at I, and under the control of the upper head of the valve P is admitted to and exhausted from the upper end of the first-stage cylinder H. The exhaust from this cylinder, retained in the receiver q<1>, is in like manner, under the control of the second head of the valve P, caused to expand in the upper end of the second-stage cylinder G, and thence exhausted into the receiver r<1>. From this receiver the steam is admitted to the annular space forming the upper end of the low-pressure cylinder A, and it is afterwards expanded in the lower end under the control of the valve heads j<1> and k<1>, working over the ports a, b. The final exhaust is controlled by the valve head l<1>, working over a port c. Ports h are provided to drain the upper side of the piston. In order to avoid the use of internal stuffing-boxes, the piston-rod 0 of the high-pressure cylinder is made to work through a fixed tube N, which projects into a hollow rod L forming an extension of the piston to which the rod is attached at the outer end. The intermediate and low-pressure pistons are made in the form of a shell closed at the upper end by a cover r, and, in the example shown, furnished with lugs for a pair of pistonrods E. These are connected to a trunk-like crosshead F working in a barrel D forming an aircushioning cylinder and guide. The valve is guided and worked by a trunk R. Fig. 2 shows in section a portion of a quintuple-expansion engine with parallel cylinders. In this, the first, fourth, and fifth stages in the expansion take place in the cylinders A, G on the right, and the second and third stages in the cylinders, which are furnished with anti-vacuum valves or openings at the lower end, on the left of the centrally-disposed valve P. This valve works in ported liners, which extend into the receiver u<1> at x<1>, y' as shown. The engines may be modified by suppressing some of the upper cylinders, so as to form single and double cylinder engines.