Filter monitoring system using a thermistor
US6507282B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 12, 2001 |
| Grant date | Jan 14, 2003 |
| Priority date | — |
| Expiry date | Aug 2, 2021 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF24F11/39
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A system for monitoring a percentage of filter life remaining of a filter assembly of filter-fan devices. The system uses a single thermistor that is operated in two separate modes for monitoring the filter assembly. The thermistor is positioned in the airflow of the filter-fan adjacent to the air outlet. A first current is applied to the thermistor for determining the temperature of the airflow from a first thermistor voltage. The first thermistor voltage is responsive to the first current applied to the thermistor. A second current that is greater than the first current is applied to the heat the thermistor. The temperature of the thermistor is determined from a second thermistor voltage which is responsive to the second current applied to the thermistor. The percentage of filter life remaining of the filter assembly is determined from the temperature of the airflow and the second thermistor voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.