SAFETY MECHANISM FOR A ROTARY HAMMER
First Claim
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1. A method for initiating a protective response in a power tool having a rotary shaft driven by a motor, comprising:
- arranging a sensing element in fixed relation to a housing of the tool to detect rotational motion of the housing about a longitudinal axis of the rotary shaft;
monitoring rotational motion of the tool about the longitudinal axis of the rotary shaft using the sensing element;
detecting speed of the motor;
setting a displacement threshold based on the detected motor speed; and
activating a protective operation by a controller disposed in the tool when rotational displacement of the tool exceeds the displacement threshold.
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Abstract
An improved method is provided for controlling a power tool having a rotary shaft. The method includes: disposing an inertial mass in a housing of the power tool, such that the inertial mass is freely rotatable about an axis of rotation which is axially aligned with the rotary shaft; monitoring rotational motion of the power tool in relation to the inertial mass during operation of the power tool; and activating a protective operation based on the rotational motion of the power tool in relation to the inertial mass.
72 Citations
18 Claims
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1. A method for initiating a protective response in a power tool having a rotary shaft driven by a motor, comprising:
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arranging a sensing element in fixed relation to a housing of the tool to detect rotational motion of the housing about a longitudinal axis of the rotary shaft; monitoring rotational motion of the tool about the longitudinal axis of the rotary shaft using the sensing element; detecting speed of the motor; setting a displacement threshold based on the detected motor speed; and activating a protective operation by a controller disposed in the tool when rotational displacement of the tool exceeds the displacement threshold. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for initiating a protective response in a power tool having a rotary shaft driven by a motor, comprising:
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disposing an inertial mass comprised of a solid cylindrical body in a housing of the power tool, the inertial mass being freely rotatable about an axis of the rotation and the axis of rotation being axially aligned with the rotary shaft, monitoring rotational motion of the housing in relation to the inertial mass; detecting speed of the motor; setting a displacement threshold based on the detected motor speed; and activating a protective operation by a controller disposed in the tool when rotational displacement of the tool exceeds the displacement threshold. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A control system for a power tool having a motor drivably coupled to a rotary shaft to impart rotary motion about a rotational axis of the tool, comprising:
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an inertial mass comprised of a solid cylindrical body disposed in a housing of the power tool, the inertial mass being freely rotatable about its longitudinal axis and axially aligned with the rotational axis of the tool; at least one sensing element in fixed relation to the housing of the power tool and configured to detect rotational motion of the housing in relation to the inertial mass; and a controller electrically connected to the at least one sensing element and operable to initiate a protective operation when rotational displacement of the housing exceeds a displacement threshold, where the displacement threshold is adjusted based on speed of the motor. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification