Saab Automobile Ab

Saab Automobile Aktiebolag

Eric Olofsson

A multicylinder internal combustion engine with an exhaust-driven turbocompressor and with a divided exhaust flow has at least two exhaust valves and one intake valve per cylinder. A first exhaust valve is connected to a first exhaust manifold which leads to the turbine of the compressor, while a second exhaust valve is connected to a second exhaust manifold which opens downstream of the turbine. In the top dead center position of the piston, the second exhaust valve and the intake valve are open at the same time for a period. The synchronization between these valves is such that the length of the period during which they are open together increases with the engine speed when the engine is driven at high load. In this way, the possibilities are improved of the engine providing good torque over a wide engine speed range.

Internal combustion engine

A turbo-fed internal combustion engine has a first and a second exhaust-gas valve per cylinder, these exhaust-gas valves each being connected to their respective exhaust manifold. One exhaust manifold conducts exhaust gases to an exhaust-gas turbine and the other exhaust manifold conducts subsequent exhaust gases past this exhaust-gas turbine which drives a compressor for charge air. The intake valve of the cylinder is arranged so as, as the engine speed increases, to close either earlier, before the piston reaches its bottom dead center, or later, after the piston has passed its bottom dead center. In this way, the temperature increase resulting from compression in the cylinder is reduced. Cooled air from the compressor can be taken in so as to obtain an adequate degree of filling in the cylinder, with a lower final temperature.

Combustion engine

In an internal-combustion engine ( ) of the Otto type, in which exhaust gases are used in order to drive a turbocompressor ( ) for supercharging the engine, the engine is designed in such a manner that it can, at high load, be run with a lean mixture during supercharging, the air/fuel ratio being at least 19:1. The lean mixture is brought about by virtue of the fact that the charging pressure increases while the fuel quantity is maintained. The engine is advantageously provided with a divided exhaust-gas discharge in order to improve the operating characteristics.

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Ronninge, Sweden

Eric Olofsson