Small siren having protective screen
US4138673A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 11, 1977 |
| Grant date | Feb 6, 1979 |
| Priority date | — |
| Expiry date | Oct 11, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10K7/04
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A siren for an alarm adapted to be driven by a fractional horsepower motor and provided with a cup shaped rotor cooperating with a stator provided with perforations in the cylindrical flange thereof, and a drawn, cup-shaped screen or grille seated over the inlet to said stator and having a cylindrical flange extending over the perforations of the stator but spaced outwardly therefrom, the base of the screen being engaged on the stator rim. The intake air flow of the siren is restricted by the perforations of the screen which increases the velocity of the intake air, thereby increasing the efficiency of the siren which enables reduction of the current usage requirements. The harmonics of the output sound are increased by the perforated cylindrical flange of the screen thereby increasing the volume and pitch of the emitted sound.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.