A Universal Steering Grommet Design Approach to Enhance the Passenger Cabin NVH Performance

As a car OEM, we continuously strive to set the bar for competitors with every product. Consumer travel experiences are enhanced by increasing passenger cabin silence. There is only one steering system opening in the firewall panel, which is used for allowing intermediate shaft's fitment on the pinion shaft of the steering gear. The steering grommet is the sole component that covers the firewall cut-out without disrupting steering operations, which has a substantial impact on the NVH performance of the vehicle. It is typically used in cars to eliminate engine noise and dust entering to passenger compartment. The part is assembled inside the vehicle where the steering intermediate shaft passing through BIW firewall panel. We use a bearing, plastic bush, or direct rubber interference design in the steering grommet to accommodate the rotational input the driver provides to turn the automobile. However, occasionally noise may be produced due to uneven bearing or plastic bush loading or a lack of flexibility in the grommet. This paper covers all the factors that must be considered when designing a better steering grommet assembly, including the flexibility of the grommet during steering operations, maintaining concentricity between the intermediate shaft and the grommet at various steering column tilt positions, and efficient packaging.