Noise suppression system

摘要

A noise suppression system for an air-cooled internal combustion engine is disclosed. The system may include an acoustically designed shroud forming a cavity and configured for attenuating noise produced by a cooling air fan associated with the engine. In one system, the shroud is mountable on a housing of the air fan. A pair of air inlet passages may be provided which are operable to draw ambient cooling air into the shroud to the fan. The air inlet passages are acoustically configured and tuned to attenuate noise generated by the fan. In one system, the air inlet passages may each be formed in a rear quadrant of the shroud. Various configurations of the shroud may include quarter wave resonators and/or micro-perforated panels to further attenuate fan noise.

主权项

1. A noise suppression shroud for an engine having a blower housing and fan positioned therein, the shroud comprising:
a longitudinal axis; a body having a lower portion mountable on the blower housing of the engine and an upper portion, the body further comprising a top wall and extending downwards therefrom a front wall, a rear wall, and opposing first and second lateral sidewalls; a cavity formed in the body; the first and second lateral sidewalls each defining a discrete first air inlet passage and a discrete second air inlet passage respectively, the first and second air inlet passages each extending rearwards beyond the rear wall and on opposite sides of the rear wall, the first and second air inlet passages being downwardly open and in fluid communication with the fan in the blower housing; a quarter wave resonator disposed in the cavity and tuned to attenuate noise within a first range of frequencies generated by the fan within the blower housing; wherein each of the air inlet passages defines a centerline which is angled obliquely to the longitudinal axis, the air inlet passages each including a rear terminal end which is spaced farther apart laterally from the longitudinal axis than a front end of the air inlet passage which is connected to the front wall of the body of the shroud; wherein the first and second air inlet passages are each operable to separately draw cooling air underneath the shroud and inwards in a forward direction towards the fan, the cooling air drawn in by the first and second air inlet passages being combined in the cavity and collectively drawn into the fan.