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US 12,576,500 B2Granted
Electric power tool, and method for controlling motor in electric power tool
AssigneeMakita Corporation
InventorsYuki Hayashi, Itsuku Kato
Life of this patent
Estimating the term…
Abstract
One aspect of the present disclosure provides an electric power tool including a motor, a drive circuit, a voltage detector, a first calculator, and a second calculator. The drive circuit applies a power-supply voltage to the motor in accordance with a first duty ratio. The voltage detector detects a magnitude of the power-supply voltage. The first calculator calculates a desired duty ratio based on the magnitude of the power-supply voltage detected. The second calculator increases the first duty ratio from an initial value to the desired duty ratio in accordance with a lapse of time. The second calculator varies a rate of increase of the first duty ratio based on the magnitude of the power-supply voltage detected.
Claims20
An electric power tool comprising:
- a grip configured to be gripped by a user of the electric power tool;
- a trigger configured to be manually moved by the user;
- a motor;
- a chuck sleeve configured to be driven by the motor, the chuck sleeve being configured to detachably receive a tool bit;
- a battery configured to supply a power-supply voltage;
- a drive circuit configured (i) to receive the power-supply voltage from the battery, and (ii) to receive a drive command, the drive command commanding the drive circuit to drive the motor, the drive command including a drive signal, the drive signal being in the form of a pulse-width modulation signal having a first duty ratio, the drive circuit being configured to apply the power-supply voltage to the motor in accordance with the first duty ratio to drive the motor;
- a voltage detector configured to detect a magnitude of the power-supply voltage based on the trigger being manually moved, the voltage detector being configured to detect the magnitude of the power-supply voltage before the drive signal is input to the drive circuit;
- a first calculator configured to calculate a desired duty ratio based on the magnitude of the power-supply voltage detected by the voltage detector;
- a second calculator configured to calculate the first duty ratio based on the trigger being manually moved, the second calculator being configured to increase the first duty ratio from an initial value to the desired duty ratio in accordance with a lapse of time, the second calculator being configured to vary a rate of increase of the first duty ratio based on the magnitude of the power-supply voltage detected by the voltage detector;
- and
- a drive command generator configured to output the drive command to the drive circuit based on the trigger being manually moved, the drive signal in the drive command having the first duty ratio calculated by the second calculator.
8 more elements
An electric power tool comprising:
- a motor;
- a drive circuit configured to receive a power-supply voltage and a drive signal, the drive signal being in the form of a pulse-width modulation signal having a first duty ratio, the drive circuit being configured to apply the power-supply voltage to the motor in accordance with the first duty ratio to drive the motor;
- a voltage detector configured to detect a magnitude of the power-supply voltage;
- a first calculator configured to calculate a desired duty ratio based on the magnitude of the power-supply voltage detected by the voltage detector;
- and
- a second calculator configured to calculate the first duty ratio, the second calculator being configured to increase the first duty ratio from an initial value to the desired duty ratio in accordance with a lapse of time, the second calculator being configured to vary a rate of increase of the first duty ratio based on the magnitude of the power-supply voltage detected by the voltage detector.
3 more elements
An electric power tool comprising:
- a motor;
- a drive circuit configured to receive a power-supply voltage and a drive signal, the drive signal being in the form of a pulse-width modulation signal having a first duty ratio, the drive circuit being configured to apply the power-supply voltage to the motor in accordance with the first duty ratio to drive the motor;
- a voltage detector configured to detect a magnitude of the power-supply voltage;
- a first calculator configured to calculate a desired duty ratio based on the magnitude of the power-supply voltage detected by the voltage detector, the desired duty ratio being required to rotate the motor at a specific desired rotational speed;
- and
- a second calculator configured to increase the first duty ratio from a specific initial value to the desired duty ratio along a first profile to thereby cause a rotational speed of the motor to reach the desired rotational speed along a first speed trajectory, the first profile being based on the magnitude of the power-supply voltage detected by the voltage detector.
3 more elements
A method for controlling a motor in an electric power tool, the method comprising:
- calculating a desired value of a duty ratio based on a magnitude of the power-supply voltage, the desired value being required to rotate the motor at a specific desired rotational speed;
- increasing the duty ratio from a specific initial value to the desired value in accordance with a lapse of time;
- varying a rate of increase of the duty ratio based on the magnitude of the power-supply voltage;
- and
- applying the power-supply voltage to the motor in accordance with the duty ratio to thereby drive the motor.
2 more elements
Dependencies are inferred from the claim text.