Electric fluid heating unit having radial PTC ceramic heating elements
US4855570A · kind A · utility
Inventor
Key dates
| Filing date | Dec 9, 1987 |
| Grant date | Aug 8, 1989 |
| Priority date | — |
| Expiry date | Dec 9, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B3/141
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
An electric heating unit for heating fluid, such as air in a hair drier, includes two ring-shaped electrodes and a plurality of spaced, plate-like ceramic heating elements having a positive temperature coefficient of resistance (PTC) aligned between the electrodes. The electrodes comprise an inner ring and an outer ring disposed in a nested, concentric, spaced relationship. The PTC ceramic plates are radially arranged in aligned spaced relationship with the opposite ends of each PTC ceramic plate mechanically and electrically connected respectively to the inner and outer rings. The inner and outer rings can be formed as arc-shaped segments separated by gaps prevent damage to the PTC ceramic plates by heat strain, and are provided with slits, grooves, etc., for firmly positioning the PTC ceramic plates.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.