Patent GB-1324394-A (GB)
Title: Supercharged fourstroke internal combustion engine
IPC: F01L7/00
Filed: 1970-08-03
Abstract: 1324394 Charging I.C. engines POWER RESEARCH & DEVELOPMENT Inc 3 Aug 1970 37446/70 Heading F1B An engine having a crank-case chamber and a cam-shaft chamber 108 which communicate via a valve 116 has air or fuel-air mixture supplied to one of the chambers for passage to the other chamber and subsequently to the head end of the cylinder 12 under the control of a valve 132 operated by a cam 140, 144 on the cam-shaft 62. In the embodiment shown, mixture from a carburetter 100 and oil from a drip lubricator 102 are fed to the chamber 108 in which they are throughly mixed by the movable members in the chamber. The mixture is drawn through a passage 110, containing a check valve 197, when the piston 6 is moving upwardly and the passage port 114 is uncovered by the port 200 in the valve disc 116 rotating with the crank-shaft 38. A crankcase outlet 120, containing a check valve 196, is connected to the inlet 136 of the cylinder 12 when the piston 16 is moving downwardly via ports 174, 176 in and the hollow interior of the slide valve 132. The valve 132 is positively reciprocated by the cams 140 and 144 which contact respective fixed abutments 142 and 146 on the valve. The valve is prevented from rotating by co-operating key 156 and keyway 158. The camshaft 62 is rotated from the crank-shaft 36 by gears 56 and 60. The cylinder 12 is connected to an exhaust passage 186 by a port 170 in the valve 132 and the interior of the valve. A valve 134, Figs.2 and 3, connects the crank-case to the head end of the cylinder 14 on alternate downward strokes of the piston 16 and to the exhaust passage 186 on the exhaust strokes of the piston portion 20. Out of phase four-stroke cycles therefore occur in the cylinders 12 and 14 during engine operation. To increase the effective volume of the crank-case chamber and thereby decrease the compression produced by downward movement of the piston 16, particularly on starting, a plug 222 in a bore 220, Fig.1, is movably manually outwardly of the bore to connect the chamber via a passage 224 to the bore. In another embodiment, Figs.7 and 8 (not shown) a carburetter (316) supplies mixture to the crank-case chamber through a flap check valve (318) and the mixture is delivered to the camshaft chamber through a flap check valve (320) for passage to the inlets (378, 380) at the head ends of the cylinders in which the stepped piston (306) operates under the control of respective piston valves (370, 372). The heads of the piston portions (428, 430) have ramps (420, 422) on their upper surfaces to effect swirling of the mixture during combustion. The piston valves (370, 372) are spring-biased against respective cams (392, 394) on the cam-shaft (312) which is connected to its driving gear (402) by a spiral gear (412). The driving gear (402) is movable manually to adjust the cam-shaft (312) relative to the crank-shaft gear (405) and thereby adjust the valve timing. A cylinder (348) depending from the crank-case (302) contains a pump piston (324) which is spring-biased against an abutment (358) and reciprocable by a cam (344) on the crankshaft (310). The cam (344) contacts a rod (334) connected to the piston (324) by a spiral gear (332) and the rod is located by splines for purely axial movement and the piston is rotatable by a handle (325) to vary its inner dead centre position and thereby the effective minimum volume of the crank-case chamber or move the rod downwardly to reduce the stroke of the piston. In a further embodiment, Figs.9 to 14 (not shown), air is supplied to the crank-case chamber for delivery to the cam-shaft chamber and a carburetter Venturi (542) is formed in the passage connecting the cam-shaft chamber to the passage containing a throttle valve (548) and a hollow slide valve (532) which controls the mixture inlet to cylinders (536, 540). The carburetter float chamber (544) is subjected through a pipe (550) to the pressure in the cam-shaft chamber. A carburetter could be provided upstream of the crank-case chamber. The inlet slide valve (532) and an exhaust slide valve (582) are operated by respective three lobed cams (560, 592) rotating in square follower openings (568) providing positive slide valve operation. To vary the effective volume of the crank-case chamber a hollow partitioned plug (600) is angularly adjustable in a bore (602) in the crank-case by a crank lever (612), Fig.14 (not shown) connected by a link (610) to a lever (608) movable by rods (604) and (606) coupled to the throttle valve and a mechanism responsive to the pressure in the cam-shaft chamber. The chambers (624...627) in the plug (600), open to the crankcase chamber through respective slots (614...617) and a slot (620) in the crank-case (502) are moved successively out of register with the crank-case slot as the plug is rotated. The effective areas of the two working portions of the stepped piston are equal.