| 摘要 |
909,034. Fluid pressure horns. COOPER'S MECHANICAL JOINTS Ltd., STREETE, C. M., and WITCHELL, S. P. May 11, 1959 [May 13, 1958; July 8, 1958], No. 15361/58. Class 13. [Also in Groups XXVII and XXVIII] A warning device, for use at the same time as a relief valve at the air intake filter of an internalcombustion engine, comprises a reiliently loaded diaphragm arranged to oscillate under differential pressure across its opposed faces and a whistle in series with the . diaphragm, the diaphragm and whistle when sounding producing a " chirping " note. The warning device is described applied to a combined filter and silencer of known type in which air is drawn in through a duct 1, Fig. 1, and passes through a filter element 3 to an outlet duct 6. The warning device 8, Fig. 1, which, as shown in Fig. 2 is provided with a whistle 17x, has a resonant cavity 9 provided with a compression spring 14 which urges the periphery of a diaphragm 16 into contact with a grommet 12. The whistle includes opposed conical plates 17a, 17b having holes 17c, 17d. When filter 3 is clogged .the pressure differential across diaphragm 16 produces oscillations of the diaphragm 16 and operation of the whistle 17x to provide the " chirping " note. The natural frequency of spring 14 and diaphragm 16 coincide with the resonant frequency of cavity 9 or a harmonic thereof. In another arrangement, Figs. 3, 5, the warning device comprising a spring-urged diaphragm and whistle in series is removably mounted on a flange 23 by a bayonet joint 26, 27. The tube 9 is spanned by a disc 24 provided with apertures 25. An imperforate layer of felt 35, acting as a filter, is adhered to the disc 24. The sound level of the device may be increased by mounting it at one end of a tube (not shown) of length equal to one quarter or one eighth the wavelength of the waves generated by the diaphragm. Specification 768,167 is referred to. |
