Refinement

Skilful structural and aerodynamic engineering minimises NVH

During the design and engineering process to create New Sorento, Kia’s research and development team prioritised achieving a major improvement in the vehicle’s refinement and minimising its NVH (noise, vibration and harshness). An excellent foundation for creating a vehicle with good NVH qualities is a stiff unitary bodyshell structure and the new Sorento features a much higher percentage (70.4%) of high-tensile strength steel compared to the previous model (40%).

Significant improvements to the all-new bodyshell include reinforced engine bay front side members, tougher longitudinal front floor members, plus more rigid joints between the dashboard bulkhead and the floor and stiffer rear wheel housings. The use of 60 kg grade high-tensile steel in the B-pillars and both the floor and roof cross-members linking them, plus the side sills and side header rails, is a key factor in creating the stiffer structure.

The new bodyshell design was evolved alongside new designs for front and rear subframes that allow the engine and front suspension and the rear suspension to be precisely mounted from beneath the vehicle during assembly. These subframes also enable engineers to isolate the cabin and its occupants from both road shocks and from vibrations generated by those components.

Other measures taken to reduce NVH include lining the engine bay bulkhead with all-new, three-layer, noise-lowering materials and injecting sound-dampening foam into the hollow sections of the bodyshell at key noise-transference points.

Further noise-reducing actions include the creation of a more streamlined bodyshell with an aerodynamic drag figure of Cd 0.38, the use of 4 mm thick glass in the front side windows, the optimised shaping of the A-Pillar and door mirror housing to minimise wind noise, and the fitting of improved seals to the doors, especially at sill-level, and to the windows.

The results are idle noise levels of 38 dB (gasoline) and 44 dB (diesel), while cabin noise during a 110 kph (68 mph) cruise is 64 dB.