Abstract: 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.

Abstract: 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.

Abstract: A balance system for a single cylinder engine is described. The single cylinder engine generates forces, that if left unbalanced, cause significant vibrations or movement to the single cylinder engine and devices driven by the single cylinder engine. The balance shaft includes a primary balance shaft for a first type of forces and at least one secondary balance shaft for a second type of forces. The secondary balance shaft is driven directly by the primary balance shaft. In one example, only one secondary balance shaft may be used, which may leave some forces unbalanced but is more space and cost effective. In another example, two or more secondary balance shafts may be included in a drive chain such that one secondary balance shaft drive the next secondary balance shaft.

Abstract: 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.

Abstract: A system for a flywheel assembly for use in conjunction with an internal combustion engine is disclosed. The flywheel assembly includes a flywheel in rotational association with a crankshaft of the internal combustion engine. The flywheel assembly further includes a cooling fan mounted over the flywheel, and capable of rotation therewith. The cooling fan and the flywheel are secured in a constant axial position relative to the crankshaft by virtue of a drive-cup and a retaining nut. Further, the flywheel includes a plurality of integrally formed, intersecting support ribs, for providing excellent dynamic stiffening (e.g., damping) capabilities to the flywheel assembly for substantially reducing and/or eliminating radiated noise.

Abstract: A system for a flywheel assembly for use in conjunction with an internal combustion engine is disclosed. The flywheel assembly includes a flywheel in rotational association with a crankshaft of the internal combustion engine. The flywheel assembly further includes a cooling fan mounted over the flywheel, and capable of rotation therewith. The cooling fan and the flywheel are secured in a constant axial position relative to the crankshaft by virtue of a drive-cup and a retaining nut. Further, the flywheel includes a plurality of integrally formed, intersecting support ribs, for providing excellent dynamic stiffening (e.g., damping) capabilities to the flywheel assembly for substantially reducing and/or eliminating radiated noise.