Elektromagnetisch betriebene Fanfare,insbesondere fuer Kraftfahrzeuge

摘要

1,216,068. Electromagnetic horns. ROBERT BOSCH G.m.b.H. 26 Sept., 1969 [28 Sept., 1968], No. 47514/69. Heading G5J. An electromagnetically operable horn comprises an electromagnetic oscillator to oscillate a diaphragm 10, and a linearly extending sound tube 171 of constant internal diameter D K whose one end is located adjacent the diaphragm and whose other end carries a bell-mouth 181 which opens in an exponential manner, the dimensions of the horn being such the length of the linearly extending sound tube is equal to a quarter of the wavelength of the desired note of the horn, the ratio of the diameter of the diaphragm D M to the diameter D K is substantially 5:1, the quotient of the diameter of the outlet of the bell -mouth and the internal diameter of the sound tube is 4 Π10%, and the quotient of the length of the bell-mouth and the diameter of the outlet of the bell-mouth is 1 Π10%. A pressure chamber 16 is recessed in a pressure chamber plate 14, which carries a magnetic system of the oscillator, and is contiguous to the sound tube, the longitudinal axis of which is perpendicular to the axis of the magnet system. The sound tube, the bell-mouth and the pressure chamber plate are integrally formed from a plastics material.