HVAC Kinematic Noise Prediction by Using Multi Body Simulation

HVAC is one of the main components on AC system on passenger car. Air flow distribution through the HVAC duct outlet as well as foot outlet is controlled mainly through HVAC kinematic mechanism. Kinematic mechanism mainly controls the air flow distribution and also temperature linearity at the outlet. Blower assembly as well as Kinematic mechanism is mainly two moving components inside HVAC system. Apart from the blower noise, another important noise generating area is kinematic noise. Due to poor cam profile and pin reaction force inside cam profile, there is high reaction force and hence produce noise. Due to different kinematic mode travel (face, foot and defrost), the pin has to be moved inside the cam profile, so pin movement & interference due to the stroke length travel leads a higher noise.

The present paper describes the noise prediction based on simulation methodology of HVAC kinematic mechanism and damper (Doors) movement. First kinematic simulation of baseline model is being conducted considering all design parameters. During simulation, fluid pressure also considered for the simulation for different modes which impacts force on kinematic doors. CAD data from CATIA software is used as parasolid format which is being used for MBD model. MBD model created on motion view software and thereafter solved using motion view. From the result, Torque as well as reaction force also calculated from MBD analysis. The pin reaction force been converted into noise which is been validated with test result.