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.
0 Assignments
0 Petitions
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.
263 Citations
28 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
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:
-
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)
-
-
15. 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 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.
-
-
16. A method for calibrating a power tool having a rotational rate sensor, comprising:
-
mounting the power tool to a test fixture, the power tool having a rotary shaft and a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft; rotating the power tool at a known angular velocity about the longitudinal axis using the test fixture; measuring, by the rotational rate sensor, an angular velocity of the power tool rotating about the longitudinal axis; and computing a first difference between the measured angular velocity and the known angular velocity. - View Dependent Claims (17, 18, 19, 20, 21)
-
-
22. A method for calibrating a power tool having a rotary shaft, comprising:
-
removing a test module from the power tool, the test module detachably couples to the power tool and houses a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft; mounting the test module to a test fixture; rotating the test module at a known angular velocity about the longitudinal axis using the test fixture; measuring, the rotational rate sensor, an angular velocity of the test module rotating about the longitudinal axis; and computing a first difference between the measured angular velocity and the known angular velocity. - View Dependent Claims (23, 24, 25, 26, 27)
-
-
28. A method for operating a power tool having a rotational rate sensor, comprising:
-
mounting the power tool to a test fixture, the power tool having a rotary shaft and a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft; rotating the power tool at a known angular velocity about the longitudinal axis using the test fixture; measuring, by the rotational rate sensor, an angular velocity of the power tool rotating about the longitudinal axis; computing a difference between the measured angular velocity and the known angular velocity; storing the difference in a memory of the power tool 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, the computation being based on input from the rotational motion sensor and the difference in the memory; 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.
-
Specification