Transducer assembly, ultrasonic atomizer and fuel burner

Abstract

A transducer assembly includes a first half wavelength double-dummy section having a pair of quarter wavelength ultrasonic horns and a driving element sandwiched therebetween. A second half wavelength stepped amplifying section extends from one end of the first section and has a theoretical resonant frequency equal to the actual resonant frequency of the first section. When used as a liquid atomizer, the small diameter portion of the stepped amplifying section has a flanged tip to provide an atomizing surface of increased area. To maintain efficiency, the length of the small diameter portion of the second section with a flange should be less than its length without a flange. A decoupling sleeve within an axial liquid passageway eliminates premature atomization of the liquid before reaching the atomizing surface. In a fuel burner incorporating the atomizer, ignition electrode life is increased by locating the electrodes outside the normal flame envelope. During the ignition phase, drive power to the atomizer is increased to widen the spray envelope to the location of the electrodes. A variable orifice controls combustion air flow in accordance with fuel rate while maintaining constant blower speed. Either three-step or continuous fuel rate modulation saves fuel and reduces pollution.