Impact tool
According to an aspect of the present invention, there is provided an impact tool including: a motor drivable in an intermittent driving mode; a hammer connected to the motor; an anvil to be struck by the hammer to thereby rotate/strike a tip tool; and a control unit that controls a rotation of the motor by switching a driving pulse supplied to the motor in accordance with a load applied onto the tip tool.
1. A power tool comprising:
a motor capable of normally rotating and reversely rotating;
a hammer rotated in a normal rotation direction or a reverse rotation direction by a driving force being supplied thereto from the motor;
an anvil struck and rotated by the rotation of the hammer,
a tip tool holding portion capable of holding a tip tool and transmitting the rotation of the anvil to the tip tool;
an electric power supply unit which alternately switches between normal rotation electric power or reverse rotation electric power so as to be supplied to the motor; and
a control unit which controls the electric power supply unit so as to increase the ratio of a period during which the reverse rotation electric power is supplied with respect to a period during which the normal rotation electric power is supplied, with an increase in an electric current which flows into the motor.
2. The power tool of claim 1 , wherein the control unit controls the electric power supply unit in a first mode in which the normal rotation period during which the normal rotation electric power is supplied is reduced, in a first step where the electric current which flows into the motor increases to a predetermined value, and controls the electric power supply unit in a second mode in which the reverse rotation period during which the reverse rotation electric power is supplied is increased, in a second step where the electric current which flows into the motor has exceeded the predetermined value.
3. The power tool of claim 2 , wherein the control unit is capable of selecting one mode from a plurality of second modes with different ratios, in the second step.
4. The power tool of claim 2 , wherein the control unit permits only shifting to a second mode with a long reverse rotation period from a second mode with a short reverse rotation period, among a plurality of second modes with different ratios, in the second step.
5. The power tool of claim 2 , wherein the control unit permits only shifting to a second mode which is adjacent in the length of the reverse rotation period, among a plurality of second modes with different ratios, in the second step.