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Patent Searching and Data


Title:
POWER TOOL
Document Type and Number:
Japanese Patent JPH08275569
Kind Code:
A
Abstract:

PURPOSE: To obtain a power tool in which soft start is combined with a brake operation by connecting one ends of the field winding and the brake winding with a terminal of a double-pole-double-throw switch and connecting the brake winding across a second switch.

CONSTITUTION: Even if a first switch 1 is turned ON to start a power tool, starting current is suppressed because of a brake winding 5 thus presenting soft start. When a second switch 2 is subsequently turned ON to short-circuit the brake winding 5 and the motor enters into steady operation, the current peak is lowered as compared with direct starting and the reaction of the tool is suppressed. When a switch lever is released, the second switch 2 is turned OFF earlier than the first switch 1 and the brake winding 5 is connected in series with a field winding 4 thus lowering r.p.m. of the motor 3. Subsequently, the first switch is turned OFF to form a brake circuit and the excitation is effected through the brake winding 5 and the field winding 4. Consequently, rotation of the armature 3 decreases abruptly and the armature is stopped.


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Inventors:
SHINOZAKI TOSHIE
Application Number:
JP7571195A
Publication Date:
October 18, 1996
Filing Date:
March 31, 1995
Export Citation:
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Assignee:
HITACHI KOKI KK
International Classes:
H02P1/18; H02P1/24; H02P3/12; H02P25/14; (IPC1-7): H02P3/12; H02P1/18; H02P1/24; H02P7/638