Mechanical brake hold circuit for an electric motor
US5327055A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1993 |
| Grant date | Jul 5, 1994 |
| Priority date | — |
| Expiry date | Mar 8, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P3/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
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 fixed 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. The circuit further prevents mechanical brake engagement even at lower motor speeds when back emf is relatively low but robot speed is fast enough to cause mechanical damage if stopped via the mechanical brake.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.