Overload protection for DC motor-driven linear actuator
US4763219A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 1, 1987 |
| Grant date | Aug 9, 1988 |
| Priority date | — |
| Expiry date | Sep 1, 2007 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H25/20
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A permanent magnet DC motor-driven linear actuator has a screw shaft supported against axial movement by a compressed spring. Excess thrust in one direction causes the shaft to move axially to open a first momentary switch, and excess thrust in the opposite direction similarly opens a second momentary switch. The switches are connected electrically in series with each other and with the motor, and enable the motor to stop whenever a mechanical overload is encountered regardless of the position of the actuator operating rod. Diodes connected across the switches in opposite directions allow reversal of the motor by reversing polarity of the DC supply, even when a switch is held open. In two of the embodiments of the invention, the swithes are double-throw switches, and additional diodes are connected from the normally open contacts of the switches to the opposite terminal of the motor to provide dynamic braking.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.