Stepped Pivot Rod for Steering Tie Rod Impact Deformation
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Solution Overview
Problem
Steering connecting rods face challenges in balancing mechanical strength for normal operation with the need for controlled deformation in case of impact, leading to increased manufacturing costs, weight, and complexity.
Innovation Solution
A tie rod design featuring a pivot rod with a head section and tail section that gradually decrease in cross-sectional area, allowing for robustness in normal operation while enabling predictable deformation in impacts, achieved through a monolithic structure that minimizes material usage and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the connecting rod is given a large cross-section to ensure sufficient mechanical strength during normal operation, then the mechanical strength is improved, but the weight and bulk of the rod increases
Solution Approach 1:
The connecting rod employs varying cross-sectional areas along its length, with larger sections positioned to handle high-stress regions during normal operation and smaller sections in low-stress regions. This localized optimization ensures sufficient mechanical strength where needed while reducing material usage and weight in non-critical areas.
Solution Approach 2:
The invention changes the geometric parameter of the connecting rod by implementing a stepped cross-sectional area profile rather than a uniform section. This parameter variation allows the rod to maintain adequate strength during normal operation while creating controlled weak points for martyr behavior during impacts, thereby reducing overall weight.
2Reliability
If a fusible groove is machined in the connecting rod to enable controlled deformation in case of impact, then the protective deformation capability is improved, but the manufacturing cost, duration, and energy expenditure increase
Solution Approach 1:
The controlled deformation capability is built into the connecting rod's geometry during the primary forming process, rather than requiring subsequent machining operations. The stepped cross-sectional profile is created directly in the manufacturing process, eliminating the need for separate fusible groove machining and reducing manufacturing complexity.
Solution Approach 2:
The invention combines the strength optimization function and the controlled deformation function into a single integrated structural feature - the stepped cross-sectional profile. This merging of functions eliminates the need for separate fusible grooves and achieves both objectives through one design element.
3Strength
If the connecting rod is designed with large cross-sections to satisfy mechanical strength criteria, then the mechanical strength is improved, but the space occupied by the steering system increases
Solution Approach 1:
The connecting rod uses non-uniform cross-sectional areas optimized for local stress requirements. Large sections are placed only where mechanically necessary to handle normal operating loads, while smaller sections are used in regions with lower stress demands, thereby reducing overall volume while maintaining required strength.
Solution Approach 2:
The invention varies the cross-sectional area parameter along the length of the connecting rod, creating a stepped profile that adapts to local mechanical requirements. This parameter optimization reduces the total volume of material needed while ensuring adequate strength where required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a balance between mechanical strength and impact deformation, reducing material usage and manufacturing complexity, resulting in a lighter, more efficient, and cost-effective steering system.
Implementation Method 1
the head section has, in the upstream-downstream direction of the axis director (XX'), a gradual decrease in its straight section, in that there is at least one gauge plane, normal to the director axis (XX') and located at an abscissa of between 15% and 40% of the center distance L0 of the connecting rod, in which the surface of the cross section of the pivot rod, called gauge section
Implementation Method 2
offers a programmed deformation, by buckling, in order to protect the rest of the steering system as well as the steering knuckle
Data Source
Figure 1~4
AI summary
The rod (1) has a pivot rod (2) that is arranged with a head section (3) on which an upstream articulation unit (4) such as kneecap sphere, is arranged. The pivot rod is arranged such that the head section presents a progressive decrease (10) of its cross-section in an upstream direction and downstream of a directing axis (X-X'). A surface of the cross-section of the pivot rod or gauge section (SJ) is located upstream of a gauge plane (PJ), and is higher or equal to a surface of a set of cross-sections (S1-S4) located downstream of the gauge plane. An independent claim is also included for a steering system.