Patent ID: 9314914
Filing Date: 2016-04-19
CPC Classification: B25F

Claim Text:
1. A power tool comprising: a motor configured to drive a tool; a rotating speed adjusting switch configured to be displaced by manipulation by a user; a regulating member configured to regulate an upper limit position when the rotating speed adjusting switch is displaced to an upper limit position of any one of a plurality of stages by the manipulation by the user; and a control unit configured to control an amount of a current flowing to the motor by a duty ratio based on a manipulation amount of the rotating speed adjusting switch, the control unit being configured to increase the rotating speed of the motor in accordance with an increase in the manipulation amount, a predetermined set number of duty ratios being set for each of the plurality of stages, and a proportion of the set number of duty ratios to a manipulable amount of the rotating speed adjusting switch being higher in a first stage, where the upper limit position is the smallest, than in stages other than the first stage, wherein the control unit is further configured to control the duty ratio so that the rotating speed increases when the manipulation amount of the rotating speed adjusting switch increases to the upper limit position at least in the first stage of the plurality of stages, and to control the duty ratio, when the manipulation amount is reduced from the upper limit position to a predetermined position, by a Hysteresis characteristic in which the rotating speed remains constant until the manipulation amount reaches the predetermined position, the predetermined position excluding an initial position of the rotating speed adjusting switch.