POWER TOOL AND CONTROL METHOD THEREOF
First Claim
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1. A power tool, comprising:
- an electric motor;
a functional accessory capable of being driven by the electric motor;
a detection device for detecting a rotational speed of the electric motor; and
a controller for controlling the rotational speed of the electric motor via use of a control signal, the controller being operable to estimate a load parameter according to a duty cycle of the control signal and the rotational speed of the electric motor whereby the estimated load parameter is used by the controller to cause the electric motor to operate at a lower rotational speed under a lower load and at a higher rotational speed under a higher load.
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Abstract
A power tool includes an electric motor, a functional accessory capable of being driven by the electric motor, a detection device for detecting a rotational speed of the electric motor, and a controller for controlling the electric motor with a control signal. The control is operable to estimate a load parameter according to a duty cycle of the control signal and the rotational speed of the electric motor such that the electric motor is caused to be operated by the controller with a lower rotational speed under a lower load and a higher rotational speed under a higher load.
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Citations
10 Claims
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1. A power tool, comprising:
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an electric motor; a functional accessory capable of being driven by the electric motor; a detection device for detecting a rotational speed of the electric motor; and a controller for controlling the rotational speed of the electric motor via use of a control signal, the controller being operable to estimate a load parameter according to a duty cycle of the control signal and the rotational speed of the electric motor whereby the estimated load parameter is used by the controller to cause the electric motor to operate at a lower rotational speed under a lower load and at a higher rotational speed under a higher load. - View Dependent Claims (2, 3, 4, 5)
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6. A control method of power tool, comprising:
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detecting a rotational speed of an electric motor; estimating a load parameter according to the rotational speed of the electric motor and a duty cycle of a control signal that is used to drive the electric motor; selecting a constant speed mode from a plurality of constant speed modes according to the load parameter; and driving the electric motor at a rotational speed corresponding to the selected constant speed mode. - View Dependent Claims (7, 8, 9, 10)
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Specification