Fluid flow sensing and control method and apparatus
US6658931B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 2000 |
| Grant date | Dec 9, 2003 |
| Priority date | — |
| Expiry date | Oct 6, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/699
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A gas mass flow sensor or probe (35, 37, 39) of an air flow sensing and control system (17, 19, 21) based upon hot-wire type devices where flow sensing is achieved by controlling the difference between two temperature sensing elements (51 and 53) suspended in the flow stream (41, 43, 45). The first element (53) is used to measure the ambient temperature of the fluid flow and the second element (51) is maintained at a programmed temperature (121) above ambient by a current-fed heater (49). The mass flow rate density is determined from heater current (117) required to maintain the temperature difference and the total flow in the duct is inferred. To measure the flow in which the elements (51, 53) are submerged, electronic circuitry monitors the two temperature elements (51, 53) and controls the amount of current through the heater (49) such that there will always be a predetermined difference between the ambient and heated temperatures. The sensor provides an output signal (101) for use by other devices (23). The output in this case is a current signal proportional to the mass flow and scaled to the input range of a utilization device. The sensor circuit (103) shuts off power to the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.