Patent FR-2910826-A1 (FR)
Title: Device for production of longitudinal ultrasonic acoustic vibrations in user element e.g. tube, comprises electro-acoustic converter with pair of piezo-electric ceramics, and intermediate element between the converter and user element
Inventor: BOURSIER GILLES
IPC: B01J19/10
Filed: 2007-01-02
Abstract: The device for the production of longitudinal ultrasonic acoustic vibrations in a user element e.g. tube, comprises an electro-acoustic converter (20) having a pair of piezo-electric ceramics (21), and an intermediate element (30) placed between the converter and user element. The piezo-electric ceramics vibrate in radial mode and its distal face (31) vibrates in bending mode. The intermediate element is arranged to the distal face of the converter in a contact zone located at a periphery, and to the user element through its plane end face. The device for the production of longitudinal ultrasonic acoustic vibrations in a user element e.g. tube, comprises an electro-acoustic converter (20) having a pair of piezo-electric ceramics (21), and an intermediate element (30) placed between the converter and user element. The piezo-electric ceramics vibrate in radial mode and its distal face (31) vibrate in bending mode. The intermediate element is arranged to the distal face of the converter in a contact zone located at a periphery, and to the user element through its plane end face. A point of the end face is animated by homogenous vibration according to a direction orthogonal to the surface. A part of the intermediate element and an other part of the user element or user ensemble are made of single-piece. A length of the contact zone is 10-15% of radius of the distal face. The intermediate element comprises a metallic cylinder having an opening, and is present in the form of disc. The cylinder has a side intended to come in contact with the converter. The vibration has an amplitude of larger than 90% of the amplitude of an antinode. The converter has an axis orthogonal to an axis of the disc that is parallel to the end surface, and is connected with a generator having alternative electric signal of ultrasonic frequency. Self-frequency of the vibration in the radial mode and self-frequency of the intermediate element are tuned to the ultrasonic frequency (80-200 KHz) of the generator. A frequency band passing through the generator is 100-300 Hz. The generator delivers an ultrasonic power of 50-10000 watt. The converter is disposed in a sealed chamber in which a cool gas or liquid circulates. The user ensemble comprises a speed transformer, a cylindrical rod and/or sonotrode constituted of an axial bar. The user element or a part of the user ensemble presents the self-frequency. A radial friction lining is arranged around the axial bar. An external radius of the friction lining is determined to include an integer of half wavelength in radial vibration mode. A liquid is pulverized by the vibration of surface situated on an external edge of the lining. The tube has two parts each fixed respectively at one of the two parts of the end surface. An independent claim is included for a process the production of longitudinal ultrasonic acoustic vibrations in a user element.