The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 02, 1992
Filed:
Jul. 12, 1990
Yoshihiro Noguchi, Saitama, JP;
Toshihisa Imai, Saitama, JP;
Yutaka Takahashi, Saitama, JP;
Ken Morinushi, Hyogo, JP;
Hideharu Tanaka, Hyogo, JP;
Mitsubishi Electric Home Appliance Co., Ltd., Saitama, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A sound attenuator has at least one sound absorber composed of a hollow body of a hard porous material and an outer or inner layer of air, and exhibits good sound-absorbing property even in a low frequency range, even if the hollow body has a small wall thickness. The hollow body may be provided with projections or a semicircular or otherwise shaped part or parts, or both, serving to maintain the outer or inner layer of air in proper shape. The device is inexpensive and yet is very reliable in quality. When the device is long, the projections in linear form are particularly useful for restraining any flanking transmission of noise and thereby enabling the device to achieve a higher rate of attenuation per unit length. The sound-absorbing property of the device can be controlled over a wide range of frequencies if the hollow body has a porosity varying continuously in a specific direction. The device exhibits an improved sound-absorbing property particularly in a low frequency range if the hollow body is provided with a skin layer on its wall surface facing an air passage.