The Study About Using Acoustic Package To Improve The Sound Performance In A Pick-up

In the design process of a domestic pickup truck,in order to approach the the NVH performance of benchmarking vehicle,taking an imported pickup truck as a benchmarking vehicle,the acoustic package of the domestic pickup truck is optimized to achieve the same level acoustic performance of the imported pickup truck.First,under different working conditions to get pressure and speech intelligibility tests of the test vehicle and benchmarking vehicle,then analyse and compare with each other,sound pressure of the test vehicle in some work conditions are higher than the benchmarking vehicle,and speech intelligibility under every condition is much lower than the benchmarking vehicle,there is a big gap between in the test vehicle and benchmarking vehicle of speech intelligibility.Therefore,improving the interior acoustic performance of the test car,reducing the sound pressure and improving the speech intelligibility are the main design objectives of this test.Considering the feasibility and the costs of the design,it is decided to use the acoustic package as a way to improve the NVH performance of the test car.Second,according to the installation principle of the acoustic package,seal andthen install.Through manual inspection、vehicle tightness inspection and ultrasonic inspection to test the sealing performance of the test car,then leakage is processed accordingly.Sealant and patch treatment deal with the Cracks and holes,air tightness test and ultrasonic inspection Confirmed leakage of gearshift rod sheath,thicken gearshift rod sheath、strengthen the seal of gearshift rod sheath and seal the A\B\C column cavity.The leakage of air tightness test was carried out on the test car treated with Sealant and patch,and the leakage of the whole vehicle was reduced by 14.8cm~2.Then the airtightness test was carried out on the test car which was replaced a new gearshift lever sheath and the A\B\C column cavity sealed,the vehicle leakage was reduced by 10.5cm~2.After plugging the air curtain,the vehicle leakage was reduced to45cm~2,the target of the seal level was reached,so the sealing work was finished.Third,based on the original car acoustic package and deficiencies analysis of test car’s sound package,PET felt was added to the engine’s decorative hood,central channel trim panel,outer side of the central channel and door trim panel,thickening the inner front wall EVA thickness,adding fusing agent to the fender,and completing the optimization plan of the acoustic package to optimize the acoustic performance of the test car.Finally,After testing the test car with acoustic package scheme,we get the test result of sound pressure and speech intelligibility.Compared with the data of the gearshift lever sheath and the seal at the A\B\C column,the reduction of sound pressure is small,and the speech intelligibility of the four seat positions is increased by 2%-4%in most of the working conditions.Compared with the origin and the benchmarking car,the sound pressure of the acoustic package is reduced by 1-3dB,The speech intelligibility is greatly improved in four position points,and the difference of speech intelligibility is controlled under 2%.The acoustic performance of the test car is improved obviously,and the better experimental results have been achieved.