Employing a shape memory alloy in a fire alarm temperature sensitive element
US4356478A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 1980 |
| Grant date | Oct 26, 1982 |
| Priority date | — |
| Expiry date | Apr 17, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B17/113
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A fire alarm is provided with a temperature sensitive element formed of a shape memory alloy, which following cold working, upon heating to a critical temperature, typically for instance about 70.degree. C., returns to the original impressed shape and also retains this shape even after subsequent recooling. Due to the movement of the element there is triggered a self-holding alarm signal, either directly by closing contacts or indirectly. Resetting of the fire alarm can be accomplished by mechanically cold working the element, or by using two-way shape memory alloys through cooling to a lower temperature threshold which can be below room or ambient temperature. A further beneficial construction is realized by combining the arrangement with a different type of fire detection or sensing element, for instance by arranging a shape memory alloy element in a scattered radiation-smoke detector. Upon reaching a critical temperature, the shape memory alloy element moves into the radiation region, or when used in an ionization fire alarm, the shape memory alloy element screens the radioactive radiation source and reduces the ionic current. Suitable shape memory alloys are, by way of example,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.