Thermally protected electric motor
US5294852A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 27, 1992 |
| Grant date | Mar 15, 1994 |
| Priority date | — |
| Expiry date | Apr 27, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02K11/25
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A laminated, metal-polymer-metal PTC resistor (8) is held in the end cap (2) of an electric motor. Substantially parallel opposed surfaces (9 and 10) of the PTC resistor (8) are engaged by electrically conductive members (11 and 12) which are respectively connected to one of the brushes (5) and one of the motor terminals (6) so that the supply of electricity is interrupted when the PTC resistor (8) is heated above a predetermined temperature as a result of excessive current flow. The PTC resistor (8) is supported against movement perpendicular to the substantially parallel opposed surfaces (9 and 10), at least in one direction, and therefore independently of at least one of the contact members (11 and 12) so that, at most, only one of the contact members (11 and 12) is needed for supporting the PTC resistor (8). Both contact members (11 and 12) can therefore make point contact with the PTC resistor (8) and this improves operation by inhibiting the conduction of heat to or from the PTC resistor (8).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.