ELECTRICALLY POWERED TOOL - HITACHI KOKI KK

Title:

ELECTRICALLY POWERED TOOL

Document Type and Number:

WIPO Patent Application WO/2017/154523

Kind Code:

A1

Abstract:

A rectifier circuit for rectifying an AC voltage supplied from a commercial power supply into a DC voltage, a smoothing capacitor for smoothing the output of the rectifier circuit, and an electrically powered tool for supplying the smoothed pulsating DC voltage to a motor by an inverter circuit, wherein when the motor is driven while no load is being applied to a tip tool, the smoothed DC voltage repeatedly generates a maximal value and a minimum value so as to synchronize with the fluctuation in the AC voltage. The duty ratios 161-166 of the PWM control when no load is being applied are restricted so as to be low, so that an interval in which the current is zero does not occur in the vicinity of the minimum value in the fluctuation. During no-load rotation, control is performed so that driving is performed at a value that is less than a threshold value D1 for the duty ratio at which the generation of a gear sound starts in any of the speed dial setting values 1-6. It is thereby possible to suppress a gear sound generated by a power transmission mechanism during no-load rotation.

Inventors:

TAKEDA YUUKI (JP)
NAKAYAMA KYOUICHI (JP)

Application Number:

PCT/JP2017/005914

Publication Date:

September 14, 2017

Filing Date:

February 17, 2017

Export Citation:

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Assignee:

HITACHI KOKI KK (JP)

International Classes:

B25F5/00; H02P6/08; H02P27/08

Foreign References:

JP2013202774A	2013-10-07
JP2012196725A	2012-10-18
JP2015037822A	2015-02-26
JP2012151962A	2012-08-09

Other References: