JPH03185209A - Exhaust noise eliminator - Google Patents

Abstract

PURPOSE:To reduce pulsation noise or the like at the time of slow speed rotation and air noise or the like at the time of high speed rotation respectively by forming an exhaust discharging pipe into a double pipe structure and arranging an opening/ closing valve between the double pipes, while opening/closing the opening/closing valve in response to the rotation speed of an engine. CONSTITUTION:Exhaust air discharged from an engine passes through an exhaust admission pipe 14, a neck pipe 17 and an intermediate pipe 16, successively and flows into each of chambers E, F, D, successively so that exhaust noise is reduced by each action of expansion and resonance. In this state, at the time of low rotational of an engine, an electric actuator 21 is controlled by a control circuit 20 so as to close the valve body 18a of an opening/closing valve 18. It is thus possible to close the outside thick pipe 15a of an exhaust discharging pipe 15 which is composed in a double pipe structure so that the exhaust air is discharged after passed through an inside thin pipe 15b, while exhaust resistance is increased so as to decrease pulsation noise or the like. On the other hand, at the time of high rotational speed of the engine, the valve body 18a is opened, so that the exhaust air is discharged after passed through the whole of the double pipes 15a, 15b. It is thus possible to suppress the exhaust resistance so as to decrease air noise or the like.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust muffler that is installed in an automobile or the like and reduces the exhaust noise of the engine, and particularly relates to an exhaust muffler that is installed in an automobile or the like and reduces the exhaust noise of the engine. The present invention relates to an exhaust muffler that has the effect of reducing low-frequency noise such as pulsation noise at low engine speeds, and the effect of reducing air flow noise and exhaust resistance at high engine speeds.

(Conventional technology)

Claims (1)

[Scope of Claims] 1. In an exhaust silencer equipped with one exhaust discharge pipe for discharging exhaust gas from a sound-reducing chamber to the outside, the exhaust discharge pipe is a double pipe, and the outer pipe of the double pipe is An exhaust muffler characterized by being provided with an on-off valve that opens and closes a passage between it and an inner pipe.