Exhaust system for multi-cylinder internal combustion engines and method

Abstract

The present invention provides methods to take advantage of the exhaust gas pulses in an exhaust system of a multi-cylinder internal combustion engine to increase the volumetric efficiency over the complete operating range of the engine. It solves the problems of other systems which are only able to gain a beneficial effect from the exhaust gas pulses over a limited range of the engine operating speeds, by providing a means of varying the exhaust pipe lengths, combinations, and cross-sectional area of the exhaust passages of the multi-cylinder internal combustion engine. By this means it provides an exhaust system in which the exhaust gas pulse frequencies can be varied over the entire operating range of the engine to obtain desirable pulse frequencies matching the cylinder exhaust timing for efficient extraction of the exhaust gases, improvement in volumetric efficiency and a higher maximum engine speed. The various methods can be controlled by sensors connected to any or all of the engine rpm sensor, the gear change mechanism and the throttle valve. The methods are suitable for any type of multi-cylinder internal combustion engine, that is, in-line cylinders, horizontal opposed cylinders, V cylinder arrangement etc. and for any type of application whether stationary or on a moving vehicle. The methods solve the problem of other methods related to positioning on a motor cycle by being able to have the exhaust pipe combination change valve located between the engine cylinder exhaust outlet and later junctions of the exhaust pipes. Also the layout of the system is such that the components can be simply protected from damage and easily accessed for maintenance.