Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.

Abstract: A highly durable engine grass screen assembly is disclosed. The assembly includes a grass screen for covering an air intake port of the engine, a grass screen stiffening mechanism for supporting the grass screen, a washer mechanism for compressing the screen such that the screen is pre-stressed during manufacture and such that the screen remains in compression during engine operation. The assembly can include one or more stud mechanisms which are securable to either an engine flywheel assembly or an engine fan assembly. The washer mechanism, the grass screen and the grass screen stiffening mechanism are engaged in a secured fashion to one or more stud mechanisms. A method of assembling and positioning a grass screen assembly in an engine is also disclosed.

Abstract: A highly durable engine grass screen assembly is disclosed. The assembly includes a grass screen for covering an air intake port of the engine, a grass screen stiffening mechanism for supporting the grass screen, a washer mechanism for compressing the screen such that the screen is pre-stressed during manufacture and such that the screen remains in compression during engine operation. The assembly can include one or more stud mechanisms which are securable to either an engine flywheel assembly or an engine fan assembly. The washer mechanism, the grass screen and the grass screen stiffening mechanism are engaged in a secured fashion to one or more stud mechanisms. A method of assembling and positioning a grass screen assembly in an engine is also disclosed.