GB892544A - Concentric triple valves for internal combustion engines - Google Patents

Abstract

892,544. Valves; combustion chambers; cooling. COLTON, R. J. Oct. 29, 1960, No. 37240/60. Classes 7(2) and 7(6). An engine having inlet and exhaust passages 5, 6 Fig. 1 communicating with a cylinder opening is provided with an internal poppet valve seat and an external seat 26 co-operating with an annular valve member 3 which is opened by exhaust gas flow when the poppet valve 2 is open and an inlet valve 7 adapted to uncover the inlet passage 6 by suction in the cylinder 49. Just before commencement of the exhaust stroke of a piston 22, a poppet valve 2 is opened by a lever 11 actuated by a follower 13 from a cam 1. The lever 11 is pivoted about a shaft 17 and carries an hydraulic lash adjuster 16. The valve 3 is unseated by gas flow during the exhaust stroke and engages push-rods 12 to compress springs 14 against fixed abutments. The valve motion is limited by the faces of the push rod guide tubes (Fig. 2 not shown) and a clearance is provided so that the valve 3 may be finally seated by gas-pressure. During the suction stroke the valve 4 is unseated from the end of a tube 8 to admit mixture into the cylinder 49 and the valve 2 is closed at the commencement of the combustion stroke. The valve 3 may have an annular depression (Fig. 4 not shown) or the shape of the poppet valve may be altered to reduce the volume of the space between the valve head and the valve 3 when closed. The push rod tubes may be assembled by the "freezing" method or may be screw-threaded. The push rod 12 diameter may be increased above the cylinder head to provide a stop and to increase the mass of the rod to provide for further compression of the springs 14 after the valve 3 abuts the push rod guide tube ends. For engines requiring constant speed operation the push rods may be omitted and the exhaust valve upward movement may be limited by either the cylinder head casting or a fixed collar on the tube 8. In another embodiment (Fig. 3 not shown) the valve arrangement is applied to a liquid-cooled four-stroke cycle L head engine. In an embodiment used in high-performance engines, the internal gas pressure on a large poppet valve 2 Fig. 5 is relieved by providing passages 67 and 82 which communicate with a cup-shaped inlet valve 4 which also forms a cylinder in which the boss 66 acts as a piston and is provided with gas seal grooves (not shown). The exhaust valve 3 is bell shaped at 79 and co-operates at its inner valve seat with a valve seat 50. The camshaft may be arranged, with appropriately modified cams, to run a half or quarter of the engine speed. Tension springs may be substituted for the compression springs and the springs for the exhaust valve may be located in the exhaust passage. The cylinder head may be of built up construction and the poppet valve may have a flat seat.