Power tool anti-kickback system with rotational rate sensor
First Claim
1. A method for initiating a protective response in a power tool having a rotary shaft rotatably driven by a motor, comprising:
- monitoring rotational motion of the tool about a longitudinal axis of the shaft using a rotation motion sensor disposed in the power tool;
determining rotational motion of the power tool based on input to a controller disposed in the power tool from the rotation motion sensor; and
reducing torque imparted by the motor to the shaft when the rotational motion determined by the controller exceeds a threshold, where the torque is set to a non-zero value that enables an operator of the tool to regain control of the tool.
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Accused Products
Abstract
A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.
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Citations
20 Claims
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1. A method for initiating a protective response in a power tool having a rotary shaft rotatably driven by a motor, comprising:
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monitoring rotational motion of the tool about a longitudinal axis of the shaft using a rotation motion sensor disposed in the power tool; determining rotational motion of the power tool based on input to a controller disposed in the power tool from the rotation motion sensor; and reducing torque imparted by the motor to the shaft when the rotational motion determined by the controller exceeds a threshold, where the torque is set to a non-zero value that enables an operator of the tool to regain control of the tool. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for initiating a protective response in a power tool having a shaft rotatably driven by a motor, comprising:
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arranging a rotational motion sensor at a location in the power tool spatially separated from the rotary shaft; imparting a torque to the shaft from a motor during normal operation of the tool; monitoring rotational motion of the tool about a longitudinal axis of the shaft using a rotation motion sensor disposed in the power tool; determining rotational motion of the power tool based on input to a controller disposed in the power tool from the rotation motion sensor; and imparting torque to the shaft by the motor at a value less than the torque imparted to the shaft during normal operation of the tool when the rotational motion determined by the controller exceeds a threshold. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification