Variable speed DC motor controller apparatus particularly adapted for control of portable-power tools
April 10, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesDrill speeder for machine tools Control device for controlling the rotational speed of a portable power tool Control device in a machine tool Power-driven screwdriver with a torque control Electric tool, particularly a handtool, with torque control Electric tool with torque monitor Rotary electrical tool with speed control, especially drill Electronically controlled screwdriver with quality check indicator Power-screwdriver device with variable torque adjustment Machine tool control system InventorsAssigneeApplicationNo. 335744 filed on 04/10/1989US Classes:173/181, Having torque sensor73/862.193, By measuring an electrical or magnetic characteristic of a torque delivering electric motor73/862.22, With variable capacity or sensitivity81/473, Rotatable, coaxial, clutching components173/20, WITH INDICATING OR SIGNALING MEANS408/9To control tool rotationExaminersPrimary: Yost, Frank T.Assistant: Fridie, Willmon Jr. Attorney, Agent or FirmInternational ClassB23Q 005/00AbstractA portable electric power tool having a DC motor for driving tool bit is controlled according to speed and torque by employing a zero displacement switch means which is coupled to the tool and operative to provide an output voltage porportional to the pressure applied to the switch means via the hand of the user. The zero displacement switch interfaces with a piezoresistive array which produces a voltage output proportional to the pressure applied to the zero displacement switch. The voltage output of the array is applied to control circuit means which are coupled to the motor and which controls the speed of the motor according to the pressure applied to the switch. There is further included motor control circuitry which operates to monitor the current through the DC motor to control the speed of the motor according to the torque imparted upon the tool bit being accommodated by the portable electric tool. | |
