Description

When the pistons of  an internal combustion engine  are in the exhaust cycle, exhaust gases arising as a result of ignition in the pistons are discharged from the engine body into the atmosphere owing to the existing exhaust system. Therefore, the back pressure faced by pistons in discharging gases is the sum of the atmospheric pressure and the pressure losses in the exhaust system. For the exhaust systems that are known today, the lowest back pressure is around the atmospheric pressure in Formula 1 racecars. In such an exhaust system, exhaust gases directly open into the atmosphere, with no muffler nor any another element present on the exhaust pipe.

Since a reduced back pressure provides an additional power and fuel saving to the engine, this is preferable by vehicle manufacturers. However, because of the severe limits imposed by environmental health protecting authorities upon the noise levels created by vehicles, it is not possible to reduce the back pressure to the atmospheric pressure except for racecars used in special raceways. This requires that  the exhaust muffler system consisting of intermediate and final mufflers in the exhaust line have to be built so as to yield sound intensity levels acceptable to environmental authorities. A muffler system operating more efficiently in general and reducing the noise level significantly will increase the back pressure. Therefore, vehicle manufacturers have to find an optimum solution between the back pressure and the sound intensity and apply it in their vehicles.

This invention relates to a muffler which is designed to create vacuum by reducing the back pressure at the exhaust of internal combustion engines below the atmospheric pressure, and keep it at a certain constant value independently of the engine operating conditions, and which is effective basically in sound absorption and mechanical frequency interference and, in addition, can also make use of the electronic frequency interference device, both due to its structure.