As the loading frequency increases, the response curve of the left/right upper mounting point in the Y direction begins to decrease after 120 Hz, and begins to meet the required range of the target dynamic stiffness, and then the response curves of the X and Z directions gradually decrease, and the requirements are met. However, the response curve in the Z direction fluctuates greatly, and it starts to rise again when it approaches 200 Hz. The dynamic stiffness test response curve of the left/lower right mounting point of the cooling fan is basically similar, but the peak points in the three directions have a tendency to move backward with the loading frequency, and the peak points are more obvious, except for the peak point. The curve is smoother rather than presenting a zigzag curve change. Analysis of the causes According to the above stiffness analysis results, the new model has a problem of insufficient jog stiffness between the cooling fan and the vehicle body at the radiator frame. The radiator frame of the new model is a quadrilateral structure in the form of integral installation. The upper and lower beam assemblies of the radiator frame are connected with the left and right vertical columns by 6 bolts respectively. The connection strength of the four corners of the structure is relatively weak, and it is difficult to ensure the stability of the quadrilateral. Sex.
The lower beam of the radiator is an open structure, and its own stability is poor during the movement. During the running of the vehicle, the high-speed operation of the fan easily drives the lower beam to bend and twist, thus causing the dynamic stiffness of the connection point between the fan and the body to meet the NVH. Performance requirements. The structural design analysis shows that the overall structural rigidity of the radiator frame of the new model is weak, especially the stability of the opening structure of the lower beam of the radiator is poor, and the fan easily causes resonance during high-speed operation, which affects the NVH performance of the whole vehicle. It is necessary to strengthen the structural rigidity of the radiator lower beam assembly.
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