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:
May. 26, 2020
Filed:
Oct. 30, 2015
Hitachi Koki Co., Ltd., Tokyo, JP;
Yuuki Takeda, Ibaraki, JP;
KOKI HOLDINGS CO., LTD., Tokyo, JP;
Abstract
Provided is an easy-to-use electric tool with which braking force can be changed according to work conditions. When an operation switchis turned off, a control unitdetects a rotation rate Rof an electric motor. The control unitstands by for a prescribed period, detects a rotation rate Rof the electric motor, and calculates the difference between the rotation rates R, R(R=R−R). Since the rotation rate difference R corresponds to the rate of change in rotation rate with time during deceleration of the electric motorand is smaller the larger the moment of inertia of the attached rotary tool, the control unitcan determine the moment of inertia of the rotary tool on the basis of the rotation rate difference R. The control unitsets the braking force according to the moment of inertia and performs braking.