Fatigue Damage Mechanism Of Loudspeaker Unit Based On Thermal Model Analysis

As a classical transducer,loudspeaker converts electrical signal into acoustic signal,but its electro-acoustic conversion efficiency is extremely low.The highest conversion efficiency of electro-acoustic is only 5%,and the conversion efficiency of some loudspeakers is even as low as 1%.Most of the electricity is converted into Joule heat during loudspeaker operation.Overheating of loudspeaker will directly lead to the change of heat transfer parameters,power compression,overheating damage of voice coil and other very serious consequences.In order to improve the performance of loudspeakers,it is necessary to study the heating mechanism of loudspeakers.In this paper,based on the heat transfer model of loudspeaker,the fatigue damage mechanism of loudspeaker unit is studied in depth.The work is as follows:(1)The most important parameter in the temperature measurement of loudspeaker coil is the average resistance temperature coefficient of coil.Aiming at the problems of long time-consuming,complex experimental device and electro-acoustic instrument cannot be combined in measurement method of coil average resistance temperature coefficient,an indirect measurement method of the average resistance temperature coefficient of the coil based on the heat transfer model is proposed.This method can obtain the temperature coefficient of the coil without measuring the temperature.Compared with the traditional measurement results,the indirect measurement method has higher accuracy.And the experimental device used in indirect measurement method is simpler and easier to operate.(2)Aiming at the requirement of loudspeaker thermal parameter measurement in life test,a method of extracting loudspeaker thermal transfer parameters from the temperature rise curve of loudspeaker coil under the condition of unsteady heating power is proposed on the basis of traditional thermal model.The difference of temperature rise curves of loudspeakers under different frequency and amplitude excitation signals is studied by using life tester.The life tester can analyze whether the heat dissipation design of loudspeaker is reasonable and whether the manufacturing process is up to the standard by measuring the variation of heat transfer parameters with the aging degree of loudspeaker.(3)The relationship between heat transfer parameters and aging rules of loudspeakers is explored through the measurement experiment of loudspeaker heat transfer parameters,and the fatigue damage mechanism of loudspeakers is analyzed.There are 54 figures,21 tables and 75 references in this paper.