Power tool
US9553542B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 2015 |
| Grant date | Jan 24, 2017 |
| Priority date | — |
| Expiry date | Jun 19, 2035 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB25D2250/221
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A hammer drill (100) comprises an electric motor (110), a piston (127) as a driving member and a controller (199) which controls and drives the electric motor (110). The piston (127) is reciprocated by rotation of the electric motor (110) and thereby a hammer bit (119) is driven in its longitudinal direction. The hammer bit (119) is moved forward in response to a forward movement stroke of the piston (127) and thereby a hammering operation is performed by the hammer bit (119). The controller (199) sets a duty ratio of a driving pulse signal which drives the electric motor (110) in the forward movement stroke of the piston (127) to be larger in order to prevent a reduction of a rotation speed of the electric motor (110) due to a load applied on the electric motor (110) during the forward movement stroke of the piston (127).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.