Patent GB-1433182-A (GB)
Title: Internal combustion engines
IPC: F02B25/04
Filed: 1973-09-27
Abstract: 1433182 Scavenging four-stroke engines MOTOREN - FORSCHUNGS GmbH & CO KG FRANKEMOTOREN 27 Sept 1973 [29 Sept 1972] 45337/73 Heading F1B An I.C. engine comprises at least two cylinders, a piston and piston-rod movable in each cylinder, a cam-shaft actuating an inlet valve and an exhaust valve for each cylinder closure means closing each cylinder on the side of the piston remote from the valves, the piston-rod passing through an aperture in the closing means, a valve means in each closure means whereby the volume between the piston and the closure means acts as a compression chamber, conduit means connecting each compression chamber with the working chamber of the cylinder so that air compressed beneath the piston can flow to the working chamber, connecting means connecting the compression chambers of cylinders in which the pistons at any moment are moving in  the same direction, valve means in the connecting means and valve actuating means operating in synchronism with the exhaust valves to connect two compression chambers in which air is being compressed to the working chamber of a cylinder during the stroke preceding the exhaust stroke thereof. Pistons 5 to 8 have piston-rods which pass through apertures in plates 39 to 42 which close the lower end of the cylinder bores. There is a non-return valve 47 in each plate and a second plate 109 is provided for each cylinder defining a space which is open to atmosphere through a port 110. There are pairs of ports 48, 50, 52, 54 in each cylinder wall, each port being connected by a passage to a corresponding lower port 49, 51, 53, 55. A slide valve 65 reciprocates between an upper position, shown in Fig. 2, in which the upper pair of ports is closed and the lower pair open and a lower position in which the upper ports are open and the lower ports are halfcovered. A rod 67 fixed to the slide valve is actuated by the exhaust valve rocker arm 28 against a spring 69 so that during the exhaust stroke air from the compression chamber under the piston 7 flows into the working chamber. Air from the compression chamber under the piston of cylinder 2, which is on the induction stroke is also pumped into the working chamber of cylinder 3 via a connecting passage 61 but does not flow into the working chamber of cylinder 2, since the slide valve of that cylinder is in its upper position. When the accelerator pedal of the vehicle in which the engine is installed is moved through the half-load position a circuit is completed which energizes a solenoid 72 and through a linkage 71 pulls the slide valve to its lower position and at the same time moves a valve member in the duct 61 to the closed position, so that each cylinder then receives only the air compressed under its own piston. The armature of solenoid 72 is connected to the central pivot point of a rocking lever, the ends of which engage downward extensions of the slide valves of two associated cylinders, i.e. two cylinders in which the pistons move instantaneously in the same direction. Alternatively the throttle pedal controlled circuit may energize three solenoids, one connected to each of the slide valves and the third connected to the valve member in the duct 61. In a flat twin engine the slide valves are spring-biased to the lower position and move thereto when a tapered distance piece is withdrawn from between them.