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 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, 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 control the rotational speed of the electric motor.
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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.
5 Citations
11 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 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, 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 control the rotational speed of the electric motor. - View Dependent Claims (2, 3, 4, 5)
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6. A control method for controlling the operation of a power tool comprising an electric motor and a functional accessory operably coupled to the electric motor to be driven by the electric motor, the control method comprising:
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detecting a rotational speed of the electric motor; controlling the rotational speed of the electric motor via use of a control signal, 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; estimating a load parameter according to the rotational speed of the electric motor and a duty cycle of the control signal, and using the estimated load parameter for controlling the rotational speed of the electric motor. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification