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US 9,267,644 B2Granted
Power tool safety mechanisms
AssigneeBlack & Decker Inc.
InventorsDavid A. Carrier, Warren A. Ceroll
Life of this patent
Estimating the term…
Abstract
A sensing mechanism (12) for detecting user contact with an active portion (26) of the power tool (10) is provided. In addition, a safety mechanism (14) for preventing prolonged user contact with the active portion (26) of a power tool (10) is provided. The safety mechanism (14) is configured to actuate upon receipt of a signal from the sensing mechanism (12). According to a first aspect, the safety mechanism (14) is arranged to rapidly displace the active portion (26) away from a user extremity. Alternatively, according to a second aspect, the safety mechanism (14) is arranged to rapidly urge an extremity of the user away from the active portion (26) of the power tool (10).
Claims21
A power tool, comprising:
- an active portion driven by a motor;
- a pawl disposed proximate to the active portion and pivotally coupled at a first end to a frame member of the power tool;
- a biasing member engaged with the pawl and operating to urge the pawl into engagement with the active portion;
- a release mechanism selectively coupled between the pawl and the frame member, wherein the pawl is disengaged from the active portion when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the active portion when the release member is uncoupled from the pawl;
- a transmitter capacitively coupled to the active portion and operable to transmit an electrical signal to the active portion;
- a receiver capacitively coupled to the active portion and operable to receive the electrical signal transmitted to the active portion;
- a controller connected to the receiver and the release mechanism, the controller operable to detect a variation in the electrical signal and send an activation signal to the release mechanism when the variation in the electrical signal exceeds a threshold value, where the release mechanism uncouples the pawl in response to the activation signals and the controller adjusts the threshold value in accordance with parasitic capacitance present at the active portion during motion of the active portion.
4 more elements
A power tool, comprising:
- a frame structure;
- a blade mounted on a spindle that is supported by the frame structure;
- a drive motor mounted to the frame structure and configured to drive the spindle;
- a pawl disposed proximate to the blade and pivotally coupled at a first end to a frame structure;
- a biasing member engaged with the pawl and operating to urge the pawl into engagement with the blade;
- a release mechanism selectively coupled between the pawl and the frame structure, the pawl being disengaged from the blade when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the blade when the release member is uncoupled from the pawl;
- a transmitter capacitively coupled to the blade and operable to transmit an electrical signal to the blade;
- a receiver capacitively coupled to the blade and operable to receive the electrical signal transmitted to the blade;
- a controller connected to the receiver and the release mechanism, the controller operable to detect a variation in the electrical signal and send an activation signal to the release mechanism when the variation in the electrical signal exceeds a threshold value, where the release mechanism uncouples from the pawl in response to the activation signals and the controller adjusts the threshold value according to parasitic capacitance present at the blade while the blade is being driven.
6 more elements
A table saw comprising:
- a frame structure with a generally flat work surface;
- a blade mounted on a spindle and being adapted to have at least a portion of the blade extending above the work surface;
- a drive motor mounted to the frame structure and configured to drive the spindle;
- a pawl disposed proximate to the blade;
- a biasing member engaged with the pawl and operating to urge the pawl into engagement with the blade;
- a release mechanism selectively coupled between the pawl and the frame structure, the pawl being disengaged from the blade when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the blade when the release member is uncoupled from the pawl;
- a transmitter capacitively coupled to the blade and operable to transmit an electrical signal to the blade;
- a receiver capacitively coupled to the blade and operable to receive said electrical signal transmitted to the blade;
- and
- a controller connected to said receiver, said controller operable to detect a variation in said electrical signal and send an activation signal to a braking mechanism when said variation in said electrical signal exceeds a threshold value, where the release mechanism uncouples from the pawl in response to the activation signals and said controller adjusts said threshold value according to parasitic capacitance present at the blade while the blade is being driven.
7 more elements
Dependencies are inferred from the claim text.