GB728453A - Improvements in or relating to multi-cylinder reversing internal-combustion engines - Google Patents

Abstract

728,453. Staring ; reversing. DOXFORD & SONS, Ltd., W., PURDIE, W., JACKSON, P., and TAYLOR, E. June 22, 1953 [March 20, 1952], No. 7250/52. Class 7(5). In a multi-cylinder reversible engine of the kind having a starting mechanism in which air under pressure is admitted into all or some of the engine cylinders in turn, the sequence of admission thereto being chosen according to the desired direction of rotation and the first cylinder in the sequence being chosen according to the positions of rotation in which the engine is standing, the starting mechanism comprising for each cylinder a starting-air inlet valve 10, Fig. 1, with compressed-air operated means, such as a piston 18, for opening the valve, two sets of air control valves, for example, two sets of grooves in a distributer rotor 25, allocated to the two directions of rotation, respectively, and for controlling the admission and release of air to and from the piston 18, and means, such as air engine driven shaft 20, for operating the control valves in timed relation to the engine, there is provided selecting means, for example, handle 41 and valve 40, for supplying air to each set of control valves according to the desired direction of rotation. The handle 41 may be moved into one of two end positions for forward or reverse starting or into a central neutral position ; in the former position air is admitted through an inlet 42, under the control of the piston valve 40 actuated by handle 41, and conduit, 43 to move the rotor 25 to the right which latter if splined to the shaft 20. The rotor 25 has grooves by which air is supplied to operate the inlet valve 10 and admit air from an inlet 91 to the cylinder ; when the rotor has turned sufficiently to admit air to the next valve 10, the previously used valve is enabled to close, by being connected by the rotor to atmosphere through one of a number of openings 29 in the distributer casing 21. Starting in the reverse direction is similarly effected by moving the handle 41 to the other end position whereupon the rotor 25 is urged to the left hand end of casing 21. In a modification, the shaft is driven by bevel gearing from the main engine shaft whilst the connection to atmosphere is made through single axial hole in the first shaft. A differential piston non-return valve 90, is provided in the starting air inlet 91, the larger piston being acted upon by air admitted thereto upon movement of handle 41 to either of its end positions. In another modification, each cylinder has two cam-actuated control-valves, one for each direction of starting, which valves control air admission to the inlet valves as in Fig. 1. When the handle is moved to start the engine in one direction or another air is admitted to all the appropriate valves through inlets 71, Fig. 11, and at the same time, air passes down channels 80 to move plungers 78 and hence rocking arms 75 to push followers 74 into engagement with cams 64 against springs 76 and permit the air to close all the valves, except that one which is held open by its cam to admit air to one of the inlet valves. As the engine and therefore the camshaft rotates the valves 60 close in the proper sequence. To relieve pressure in the outlet connections 81 there is provided a port 83 which connects with atmosphere through an axial passage 84 in the valve stem and a port 87 in a shroud 86 over the end of the stem. The shroud seals the end of the passage 84 during the initial opening of the valve. The shaft carrying the rotor or cams may be driven from the engine through a clutch which is engaged when the fuel is cut off and vice versa ; the clutch may however be of the type which disengages automatically when a given engine speed is attained. The inlet valves may be diaphragm operated. Specification 710,533, [Group XXVIII], is referred to.