Ultrasonic temperature sensors, and ultrasonic waveguide connectors for use therewith
US5022014A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 14, 1989 |
| Grant date | Jun 4, 1991 |
| Priority date | — |
| Expiry date | Jun 14, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10K11/24
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An ultrasonic fire detector comprises an elongate ultrasonic waveguide, e.g. in the form of a wire, which is arranged to be strung around the area to be monitored for fire. An ultrasonic pulse generator launches longitudinal ultrasonic pulses into one end of the waveguide, for reflection from the far end. The waveguide is arranged such that local heating due to a fire changes its acoustic impedance at the location of the local heating, the change in acoustic impedance being sufficient to produce partial reflection of the ultrasonic pulses. Detection of the partially reflected pulses thus indicates the presence of a fire, and their time of arrival gives the location of the fire along the waveguide. The acoustic impedance change can be produced by providing the waveguide with notches filled with low melting-point alloy, by applying a temperature-induced stress to the waveguide, or simply by the temperature gradient caused by the fire. Sections of waveguide can be joined together by an ultrasonic waveguide connector comprising two horn-shaped connector portions, each having a narrower end which is welded or brazed to a respective one of the waveguides, and a wider end which is extreme…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.