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:
Jul. 14, 1992
Filed:
Aug. 09, 1991
Shinichi Ohi, Konan, JP;
Zexel Corporation, Tokyo, JP;
Abstract
A noise prevention apparatus for a blower unit using a brushless motor is disclosed in which, when a setting speed of rotation set by a rotational speed setting unit is judged as being equal to a speed of rotation corresponding to a natural frequency of the blower unit, a drive pulse which is to be provided to a switching unit for controlling the rotation of the blower is corrected by a drive pulse correction unit such that the setting speed of rotation is deviate from the speed of rotation corresponding to the natural frequency of the blower unit. With this arrangement, the brushless motor is driven at speeds other than the speed corresponding to the natural frequency of the blower. Consequently, a higher harmonic of the vibration of the motor is always kept out of coincidence with the natural frequency of the blower unit, so that a operation noise caused by resonance does not take place any more.