Front Vehicle-Body Structure Reducing Windshield Vibration
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Solution Overview
Problem
Existing front vehicle-body structures fail to effectively reduce second-order vibration of windshields during vehicle travel, leading to poor NVH performance and discomfort for occupants due to inadequate rigidity enhancement at the cowl mounting region of the tower bar.
Innovation Solution
A front vehicle-body structure design featuring a tower bar with a center portion extending along the cowl, a bracket extending from the cowl to the front, and a reinforcement member supporting the fixing region from below, with specific configurations to enhance bending rigidity and offset mounting positions to reduce vibration nodes and amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cowl is designed with a closed cross-section structure to enhance rigidity, then the rigidity of the cowl is improved, but the tower bar cannot be directly mounted on the cowl, requiring additional brackets and reducing the effectiveness of vibration reduction
Solution Approach 1:
A bracket is introduced as an intermediary component between the tower bar and the cowl. The bracket extends from the cowl toward the front of the vehicle, and the center portion of the tower bar is fixed to the bracket from above. This intermediary structure enables the tower bar to be mounted on a closed cross-section cowl while maintaining the ability to reduce second-order vibrations of the windshield.
2Device complexity
If a simple bracket structure is used to mount the tower bar on the cowl, then the device complexity is reduced, but the rigidity of the mounting portion is insufficient to effectively reduce second-order vibration of the windshield
Solution Approach 1:
The mounting structure is segmented into multiple functional components: the bracket extending from the cowl, the reinforcement member supporting the fixing region from below, and the tower bar fixed from above. This segmentation allows each component to perform its specific function optimally while working together to reduce vibrations.
Solution Approach 2:
The reinforcement member is positioned in a different spatial dimension (from below) relative to the bracket (extending from the front), creating a three-dimensional support system. This multi-dimensional arrangement enhances the rigidity of the mounting portion without simply increasing the complexity of a single-component structure.
3Device complexity
If the tower bar is mounted at a single central position on the cowl, then the mounting structure is simplified, but the vibration nodes cannot be effectively targeted to reduce second-order vibrations
Solution Approach 1:
The bracket and reinforcement member are specifically positioned to target the vehicle-width-direction center portion region of the cowl, which corresponds to the node region of second-order vibrations. This localized reinforcement at the critical mounting position enhances vibration reduction effectiveness without requiring complex multi-point mounting structures.
Data Source
AI summary
A front vehicle-body structure for reducing second-order vibration of a windshield, and improving NVH performance in a vehicle cabin. A tower bar coupling each of left and right front suspension housings with a region around a vehicle-width-direction center portion of a cowl forming a lower edge of an opening for a front windshield has a center portion extending in a vehicle width direction along the cowl. A bracket extending from the cowl toward a front of a vehicle is provided in a region including a vehicle-width-direction center portion of the front windshield in the lower edge of the opening. The center portion of the tower bar is fixed to the bracket from above, and a reinforcement member supporting the fixing region from below is provided.