ELECTRIC TOOL AND CONTROLLING METHOD THEREOF
First Claim
1. A method for controlling an electric tool, the electric tool comprising an electric motor and an output shaft which is driven by the electric motor and configured for outputting a rotary torque to drive a tool bit to work on a work piece;
- the method comprising;
measuring a parameter representing the load on the output shaft in dependence on time,calculating a second or higher derivative of the parameter in dependence on time,generating a control signal according to the second or higher derivative, andchanging a rotational speed of the electric tool in response to the control signal.
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Accused Products
Abstract
A power tool including a motor for rotatably driving a tool bit at an attained rotational speed, a source for supplying an electric current to the motor, a sensor for measuring the current, and a control device. The control component fulfils the task of detecting a variation of the slope of the current in the course of time, and generates a control signal. The rotational speed of the tool is reduced in response to the control signal. The power tool automatically detects whether the work piece operated by the tool bit reaches a predetermined position by electronic control means. It may make sure that the screw is driven into a piece of wood and does not go beyond the predetermined position once it detects that the work piece reaches the position and carries out a changing action.
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Citations
19 Claims
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1. A method for controlling an electric tool, the electric tool comprising an electric motor and an output shaft which is driven by the electric motor and configured for outputting a rotary torque to drive a tool bit to work on a work piece;
- the method comprising;
measuring a parameter representing the load on the output shaft in dependence on time, calculating a second or higher derivative of the parameter in dependence on time, generating a control signal according to the second or higher derivative, and changing a rotational speed of the electric tool in response to the control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- the method comprising;
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11. An electric tool, comprising:
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an output shaft, an electric motor configured to drive the output shaft to rotate, a power supply for supplying power to the electric motor, a sensor for measuring a parameter representing the load on the output shaft, and a control component configured to calculate a second or higher derivative of the parameter in dependence on time, and generate a control signal according to the second or higher derivative to change a rotational speed of the electric motor. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for controlling an electric tool, comprising:
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measuring a parameter representing the load on the electric tool in dependence on time, calculating a second or higher derivative of the parameter in dependence on time, generating a control signal according to the second or higher derivative, and changing the rotational speed of the electric tool in response to the control signal.
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19. An electric tool, comprising:
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a sensor for measuring a parameter representing the load on the electric tool, and a control component configured to calculate a second or higher derivative of the parameter in dependence on time, and to generate a control signal according to the second or higher derivative to change a rotational speed of the electric tool.
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Specification