Guard Detection System For A Power Tool

摘要

A power table saw has a saw blade driven by a drive motor with power selectively supplied to the drive motor by actuation of a mains switch. A riving knife is provided that can be selectively positioned in an extended position and a retracted position relative to the blade. A blade guard is removably mounted to the riving knife in a position above the blade. A sensible element on the riving knife can be detected by a first sensor when the riving knife is retracted, the first sensor having a non-null state when the sensible element is adjacent the first sensor and a null state otherwise. A second sensor is configured to detect the presence of the blade guard and has a null state when the blade guard is detected and a non-null state otherwise. A controller is operable to determine the states of the first and second sensors and to disengage power to the drive motor when the mains switch is actuated when the states of the first and second sensors are different.

主权项

1. In a power table saw having a table top surface with an opening through which a blade can extend, the blade being driven by a drive motor supported by a carriage relative to the top surface, a mains switch selectively actuatable by an operator to provide power to the drive motor, and a riving knife slidably supported on the carriage to be selectively position the riving knife in an extended position in which the riving knife extends through the opening adjacent the blade and a retracted position in which the riving knife is retract below the table top surface, the improvement comprising:
a sensible element mounted to the riving knife; a first sensor arranged in the power table saw to detect the sensible element when the riving knife is in the retracted position and to generate a signal when the sensible element is adjacent the sensor; and a controller operable to disengage power to the drive motor when the mains switch is actuated upon receipt of the signal from said first sensor.