US 5,394,069 AGranted

Mechanical brake hold circuit for an electric motor

AssigneeInternational Business Machines Corporation

InventorsCraig T. Danielson, Gregory T. Kishi, Michael P. McIntosh, Hector E. Mery, Scott M. Rockwell

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Abstract

An automated tape library employing a motorized robotic picker wherein the electric motor driving the robotic picker is equipped with two brakes that act simultaneously. The first is a mechanical brake which uses a spring to push a brake pad against the rotating motor. During normal motor operation, an electric solenoid is used to overcome the spring and disengage the brake pad from the motor. When the robotic picker is to be mechanically stopped, the solenoid voltage is turned off and the solenoid releases the spring placing the brake pad in contact with the motor. The second brake is a dynamic electrical brake which makes use of the back emf of the motor to drive a current back into its own windings such that the motor decelerates.

Claims8

Dependent claims

A dynamic braking circuit for an electric motor comprising:

a mechanical brake power supply having first and second terminals;
a first relay having first, second, third and fourth movable contacts and a coil, said coil having first and second terminals;
a brake solenoid having first and second terminals;
said first movable contact of said first relay being connected between said first terminal of said coil of said first relay and said first terminal of said brake solenoid;
said second movable contact of said first relay being connected between said second terminal of said coil of said first relay and said second terminal of said brake solenoid;
said third movable contact of said first relay being connected between said second terminal of said brake solenoid and said first terminal of said brake power supply;
said fourth movable contact of said first relay being connected between said first terminal of said brake solenoid and said second terminal of said brake power supply;
a first resistor having a first and second terminal and being connected to a conversion means and being further connected to said electric motor, and said conversion means being connected to said first relay.

5 more elements

Dependencies are inferred from the claim text.