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Apparatus which controllably meters dry powder from a powder supply chamber falling through a vertically disposed axial passageway interconnecting the supply chamber with a mixing chamber therebelow for forming an air-powder mixture therein for transport to a desired site. A tapered plug member is b

Apparatus which controllably meters dry powder from a powder supply chamber falling through a vertically disposed axial passageway interconnecting the supply chamber with a mixing chamber therebelow for forming an air-powder mixture therein for transport to a desired site. A tapered plug member is bonded to a bimorph bender comprising a piezoelectric element bonded to each face of a thin, flat, cantilevered metallic beam which is deflectable by a dc bias or driving voltage applied to the bender to cause the tapered plug to penetrate or move within the passageway, thus varying width of annular gap formed between the plug and passageway, and hence, amount of powder capable of falling therethrough. An oscillating voltage may be impressed upon the piezoelectric elements to cause the deflected beam to additionally be vibratorily displaced in accordance with the frequency of vibrations of the impressed oscillating source.

대표청구항 ▼

Dry powder metering apparatus comprising a cylindrical body member having a powder supply chamber and an air-powder mixing chamber at its upper and lower portions respectively, a vertically axially disposed passageway interconnecting said chambers, an electrically conductive horizontal beam cantilev

Dry powder metering apparatus comprising a cylindrical body member having a powder supply chamber and an air-powder mixing chamber at its upper and lower portions respectively, a vertically axially disposed passageway interconnecting said chambers, an electrically conductive horizontal beam cantilevered to said body member and extending radially inwardly beneath said passageway, throttling means movable with said beam and penetrable into said passageway for providing a controlled annular gap between said throttling means and said passageway, a piezoelectric element bonded to each of an upper and lower face of said beam to form a bimorph bender with means for completing a dc circuit therethrough for controllably deflecting said beam to change width of said annular gap as said throttling means is moved substantially vertically within said passageway, and wherein an oscillating voltage is impressed upon said bimorph bender to produce oscillations thereof, said oscillations having a fixed frequency to cause said deflected beam to be vibratorily displaced in accordance with the frequency of said oscillations, and additional means for pressurizing said chambers whereby powder flowing through said gap forms an air-powder mixture for transport thereof from said mixing chamber.