Electronic clutch for power tool
First Claim
1. A power tool comprising:
- a housing;
an output spindle;
an electric motor disposed in the housing and configured to provide torque to the output spindle;
an input switch for actuating the motor;
an electronic clutch configured to interrupt transmission of torque to the output spindle when a threshold torque value is exceeded, the electronic clutch includinga current sensing circuit that generates a sensed current signal that corresponds to an amount of current being delivered to the motor;
a rotation sensing circuit that generates a sensed rotation signal that corresponds to at least one of an angular position, a speed, and an acceleration of the motor output shaft; and
a controller coupled to the current sensing circuit and the rotation sensing circuit, wherein the controller, in a first mode of operation, initiates a first protective operation to interrupt transmission of torque to the output spindle when the sensed rotation signal indicates that the rotational speed of the motor is decreasing and the sensed current signal exceeds a first current threshold value.
1 Assignment
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Accused Products
Abstract
A method is presented for controlling operation of a power tool having an electric motor drivably coupled to an output spindle. The method includes: receiving an input indicative of a clutch setting for an electronic clutch, where the clutch setting is selectable from a plurality of driver modes; setting the value of a maximum current threshold in accordance with the selected one of the plurality of driver modes; determining rotational speed of the electric motor; determining an amount of current being delivered to the electric motor; comparing the amount of current being delivered to the electric motor to the maximum current threshold; and interrupting transmission of torque to the output spindle when the amount of current being delivered to the electric motor exceeds the maximum current threshold and the rotational speed of the electric motor is decreasing.
123 Citations
20 Claims
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1. A power tool comprising:
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a housing; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; an input switch for actuating the motor; an electronic clutch configured to interrupt transmission of torque to the output spindle when a threshold torque value is exceeded, the electronic clutch including a current sensing circuit that generates a sensed current signal that corresponds to an amount of current being delivered to the motor; a rotation sensing circuit that generates a sensed rotation signal that corresponds to at least one of an angular position, a speed, and an acceleration of the motor output shaft; and a controller coupled to the current sensing circuit and the rotation sensing circuit, wherein the controller, in a first mode of operation, initiates a first protective operation to interrupt transmission of torque to the output spindle when the sensed rotation signal indicates that the rotational speed of the motor is decreasing and the sensed current signal exceeds a first current threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A power tool comprising:
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a housing; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; an input switch for actuating the motor; and an electronic clutch configured to interrupt transmission of torque to the output spindle when a threshold torque value is exceeded, the electronic clutch including a current sensing circuit that generates a sensed current signal that corresponds to an amount of current being delivered to the motor; and a controller coupled to the current sensing circuit wherein the controller, in a first mode of operation, initiates a first protective operation to interrupt transmission of torque to the output spindle when the sensed current signal exceeds a first current threshold value, and initiates a second protective operation to interrupt transmission of torque to the output spindle when the controller determines that the switch has been actuated a second time within a predetermined time after the first protective operation to continue driving a fastener after the first protective operation and the sensed current signal exceeds a second current threshold value that is less than the first current threshold value. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A power tool comprising:
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a housing; a clutch setting input device disposed on the housing and configured to receive a user selection of a clutch setting; an output spindle; an electric motor disposed in the housing and configured to provide torque to the output spindle; a controller coupled to the motor and configured to control delivery of electric current to the motor, wherein the controller is configured to;
(a) receive an input indicative of a clutch setting from the clutch setting input device;
(b) determine a value of a maximum current threshold in accordance with the selected clutch setting;
(c) determine a rotational speed of the electric motor;
(d) determine an amount of current being delivered to the electric motor;
(e) compare the amount of current being delivered to the electric motor to the maximum current threshold; and
(f) initiate a protective operation to interrupt transmission of torque to the output spindle when the amount of current being delivered to the electric motor exceeds the maximum current threshold and the rotational speed of the electric motor is decreasing.
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Specification