GB849452A - Siren - Google Patents

Abstract

849,452. Sirens. BLANCHARD, J. M. Dec. 12, 1956 [Dec. 16, 1955], No. 37945/56. Class 13. In a rotary siren packing is provided in the space, or spaces, between the rotor and the part, or parts, co-operating therewith for preventing leakage of fluid thereinto. As shown in Fig. 6 the rotor 2e has recesses 35 at its periphery within which are apertured weights 34 provided with fluid tight rings 36. When the rotor is driven the weights 34 are urged against the ring 33 secured to the stator, which ring has parts 31a, 31b therin, the rounded heads 37 of the weights 34 providing for fluid tightness and preventing any substantial leakage of fluid into the space 38. In the embodiment of Fig. 8 the rotor is a disc 2J having perforations on a circle coaxial with its rotary axis 3J and the stator consists of two solid flanges 86, 87. Fluid fed under pressure into pipe 89 enters an annular channel 90 from which auxiliary channels 91a, 91b feed nozzle-shaped injectors 92a, 92b distributed uniformly round the axis 3J at a radius equal to that of the circle on which the perforations in the rotor lie. The flange 87 has corresponding ejector nozzles 93a, 93b connected via radial channels 94a, 94b with the bell-shaped member 101. The adjustable pistons 96a, 96b, 97a, 97b allow the injector and ejector nozzle chambers to be tuned to the frequency produced by the siren. Fluid tight packings 100 are fitted between the rotor 2J and each of the flanges 86 and 87. The packings are preferably of polytetrafluoroethylene which may be operated at temperatures up to 300‹ C. In other embodiments there is no stator, but contra-rotating rotors are provided.