Abstract: Methods to detect when a human body contacts a predetermined portion of a machine are disclosed. The methods distinguish contact with a person from contact with other materials. The methods are particularly applicable in woodworking equipment such as table saws to distinguish contact between a person and the blade of the saw from contact between the blade and wet or green wood. The methods and woodworking equipment may include predictive blade stop algorithms that prevent unnecessary activations of a safety brake during coast down of a blade and continued protection in the event a main power switch is turned off.
Abstract: A power tool comprises a base unit and a motor unit. The base unit includes a handle and a first electrical connector. The motor unit includes an electric motor and a second electrical connector. The motor unit is configured to be releasably connected to the base unit. An electrical connection is established between the first electrical connector and the second electrical connector when the motor unit is properly connected to the base unit. A sensor is configured to determine whether the motor unit is properly connected to the base unit.
Type:
Grant
Filed:
February 13, 2009
Date of Patent:
April 12, 2011
Assignee:
Robert Bosch GmbH
Inventors:
David Pozgay, Charlie Ren, Jeff Schreiner
Abstract: A stump cutter controller and operator presence system includes one or more capacitive sensors in each of the three control levers that control movement of the cutter wheel. A sensor circuit measures changes in the capacitance of the sensors. The controller automatically disengages a drive clutch and applies a brake to the cutter wheel when the controller senses that an operator has left the operating station—which is assumed when the operator has not touched any one of the three control levers of the operator station for a predetermined time. The controller logic is set to allow the clutch to remain engaged during a delay period, of predetermined duration, to permit the operator to move a hand off of one control lever to another control lever. Also, a grace period, of varying duration based on the speed of the cutter wheel, may be provided during which the clutch is reengaged if an operator returns to the controls.
Type:
Application
Filed:
July 29, 2008
Publication date:
April 9, 2009
Applicant:
Vermeer Manufacturing Company
Inventors:
Ivan R. Brand, Brent Allen Bartels, John R. Powers, Douglas E. Ammons