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, comprising:
- monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool;
computing angular displacement of the power tool about the axis of the rotary shaft using a controller disposed in the power tool and based on input from the rotational motion sensor;
initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and
initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements.
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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
23 Claims
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1. A method for initiating a protective response in a power tool having a rotary shaft, comprising:
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monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool; computing angular displacement of the power tool about the axis of the rotary shaft using a controller disposed in the power tool and based on input from the rotational motion sensor; initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for initiating a protective response in a power tool having a motor drivably coupled to a rotary shaft to impart rotary motion thereto, comprising:
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monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool; determining angular displacement of the power tool about the axis of the rotary shaft from a baseline using a controller disposed in the power tool and based on input from the rotational motion sensor; initiating a protective operation in the power tool by the controller when a first operating condition of the power tool exceeds a first operating threshold and angular displacement of the power tool falls within a first range of angular displacements; and initiating a protective operation in the power tool by the controller when a second operating condition of the power tool exceeds a second operating threshold and angular displacement of the power tool falls within a second range of angular displacements, where the second operating condition is different than the first operating condition and the second range of angular displacements is mutually exclusive of the first range of angular displacements. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for initiating a protective response in a power tool having a rotary shaft, comprising:
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monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool; computing angular displacement of the power tool about the axis of the rotary shaft from a baseline using a controller disposed in the power tool and based on input from the rotational motion sensor; periodically resetting the baseline when angular velocity of the power tool about the axis is less than a velocity threshold; initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements.
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16. A method for controlling operation of a power tool having a rotary shaft, comprising:
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monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool, wherein the rotation motion sensor is further defined as an accelerometer; computing angular displacement of the power tool about the axis of the rotary shaft based on input from the rotational motion sensor and using a controller disposed in the power tool; and driving the rotary shaft at a given rotational speed, where the given rotational speed is set to a non-zero value based on the angular displacement of the power tool. - View Dependent Claims (17, 18, 19)
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20. A method for controlling operation of a power tool having a rotary shaft, comprising:
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monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool, wherein the rotation motion sensor is further defined as a gyroscope; computing angular displacement of the power tool about the axis of the rotary shaft based on input from the rotational motion sensor and using a controller disposed in the power tool; and driving the rotary shaft at a given rotational speed, where the given rotational speed is set to a non-zero value based on the angular displacement of the power tool. - View Dependent Claims (21, 22, 23)
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Specification