Electric power tool, control unit and recording medium
First Claim
Patent Images
1. An electric power tool, comprising:
- a direct current motor that is rotated by electric power supplied from a direct current power source and drives a tool bit;
at least one switching device that is provided on a current path from the direct current power source to the direct current motor;
a trigger switch operated by a user;
a control unit that sets a driving duty ratio for PWM controlling the direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when an operation of the trigger switch is started until when a predetermined start-up time has elapsed; and
a drive unit that turns on/off the at least one switching device in accordance with the driving duty ratio set by the control unit to thereby rotate the direct current motor.
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Abstract
An electric power tool includes a direct current motor, at least one switching device, a trigger switch, a control unit, and a drive unit. The control unit sets a driving duty ratio for PWM controlling the direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when an operation of the trigger switch is started until when a predetermined start-up time has elapsed.
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Citations
9 Claims
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1. An electric power tool, comprising:
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a direct current motor that is rotated by electric power supplied from a direct current power source and drives a tool bit; at least one switching device that is provided on a current path from the direct current power source to the direct current motor; a trigger switch operated by a user; a control unit that sets a driving duty ratio for PWM controlling the direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when an operation of the trigger switch is started until when a predetermined start-up time has elapsed; and a drive unit that turns on/off the at least one switching device in accordance with the driving duty ratio set by the control unit to thereby rotate the direct current motor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A control unit comprising:
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an operation detecting section that detects an operation of a trigger switch operated by a user; and a duty ratio setting section that sets a driving duty ratio for PWM controlling a direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when the operation detecting section detects the operation of the trigger switch until when a predetermined start-up time has elapsed.
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9. A recording medium readable by a computer, the recording medium recording a program for causing the computer to execute:
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an operation detection step of detecting an operation of a trigger switch operated by a user; and a driving duty ratio setting step of setting a driving duty ratio for PWM controlling a direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when the operation of the trigger switch is detected in the operation detection step until when a predetermined start-up time has elapsed.
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Specification