Structural Performance Improvement of an Automotive HVAC Refrigerant Line Design Using FEA Techniques

Customer expectations on enhanced comfort and luxury always increasingly demand the continuous development of automotive HVAC control system in a passenger car. The role of HVAC system in modern vehicle is to act as a climatic control system thereby managing pleasant temperature environment desired by the occupants inside the cabin. Refrigerant line which is part of HVAC system is a closed loop system through which refrigerant circulates inside to absorb heat from passenger compartment. Refrigerant line is connected to compressor that coupled with engine and it is mounted to vehicle body at various locations based on specific packaging requirements. The refrigerant line design needs to be robust to ensure its structural rigidity in both static and dynamic loading conditions. Especially the dynamic load experienced by the HVAC refrigerant line is a combination of periodic sinusoidal vibration excitation from powertrain and random vibration excitation from road through vehicle body. Hence, parameters like static, dynamic stress and attachment dynamic stiffness are to be assessed during design phase and these parameters are validated through finite element analysis (FEA) techniques. Finite element analysis enables upfront design improvement in terms of improving or optimizing the refrigerant line design at power train attachment region. The objective of this paper is to present the virtual validation process for design improvement of an existing HVAC refrigerant line, which encountered a structural problem in physical validation under powertrain loading conditions. Correlation of simulation results with the physical validation and enhancement of virtual validation process are also discussed in this paper.