Patent ID: 7688681

Claim:
An ultrasonic rod transducer ( 1 ) for generation of ultrasound in liquids comprising: a housing ( 10 , 11 ) that bounds an inner space and has an outer wall ( 28 , 29 ) with an inner side ( 32 ) facing the inner space, a piezoelectric transducer device ( 8 ) having two end faces and which is disposed in said housing ( 10 ), a resonator ( 2 ) situated outside of the housing ( 10 , 13 ), a connecting element ( 7 ) for connecting said transducer device ( 8 ) to said resonator ( 2 ), a heat transfer element ( 9 ) thermally connected to said piezoelectric transducer ( 8 ) and having an outer surface ( 24 ) that extends adjacent to said inner side ( 32 ) of said outer wall ( 28 ) to form a gap ( 34 ) of between 0.5 mm and 5 mm through which heat of the piezoelectric transducer ( 8 ) is transferred to the outer housing wall ( 28 ); and said heat transfer element ( 9 ) having an acoustical length of λ/2 in a direction parallel to the axis of oscillation of the piezoelectric transducer (a).