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:
Aug. 25, 2015
Filed:
Feb. 16, 2009
Kazutaka Iwata, Hitachinaka, JP;
Kenichirou Yoshida, Hitachinaka, JP;
Shinji Watanabe, Hitachinaka, JP;
Kazutaka Iwata, Hitachinaka, JP;
Kenichirou Yoshida, Hitachinaka, JP;
Shinji Watanabe, Hitachinaka, JP;
HITACHI KOKI CO., LTD., Tokyo, JP;
Abstract
A current detection circuit () detects that a drive current of the stator coil () is exceeding a threshold value Ir. A rotation number detection circuit () detects that the number of rotations of a rotor () is lower than a threshold value Nr. A computing part () outputs a PWM signal which switches a semiconductor switching element () of the inverter circuit part (). The computing part () changes the threshold values Ir and Nr in accordance with the PWM duty of the PWM signal determined in accordance with a pressed distance of a switch trigger () and detects a locked state of the motor () on the conditions that the motor current I is exceeding the set threshold value Ir and that the number of rotations N thereof is lower than the threshold value Nr.