Solid state mass air flow sensor
US4487063A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 11, 1983 |
| Grant date | Dec 11, 1984 |
| Priority date | — |
| Expiry date | Jul 11, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/698
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A hot element anemometer uses solid state diode chips for the heated air flow sensing element and the ambient temperature sensing element in parallel circuit branches. The air flow sensing element carries a heating resistor on the diode chip. Constant current sources of equal value supply current through the diodes. The air flow sensor diode is in series with a resistor which determines the nominal temperature difference between the diode chips. A circuit compares voltages in the two diode branches and provides an air flow output signal and controls the temperature of the air flow sensor diode. To compensate for changes of thermal conductivity of the air temperature and various temperature effects in the circuit, a third current source is coupled to the ambient temperature sensing branch through a resistor network and includes resistors that can be adjusted to provide a functional calibration which yields an air flow signal free of linear temperature effects.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.