Level detector for fluent material
US5943294A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1998 |
| Grant date | Aug 24, 1999 |
| Priority date | — |
| Expiry date | May 1, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S367/908
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A vibrating probe for detecting a threshold level within a vessel of fluent material, particularly a liquid, includes: an ultrasonic acoustic transducer assembly comprising a transducer element having a natural resonant frequency, and loading elements effective to shift that frequency to an effective resonant frequency of the assembly, the assembly being supported within the vessel and including a coupling member to couple the transducer acoustically to liquid reaching the threshold level, a transmitter generating pulses applied to the transducer element for repeatedly exciting the transducer element to cause the transducer assembly to resonate at its effective resonant frequency, a circuit for measuring the effective resonant frequency of the transducer over a ringdown period following cessation of each pulse, and a circuit for comparing the effective resonant frequency measured during the ringdown period following each pulse with a predetermined threshold level. The threshold level is selected so as to distinguish between the effective resonant frequency of the assembly in free air and a lower effective resonant frequency when coupled to fluent material through the coupling membe…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.