Steering Spindle Tube Structure for Bearing Stiffness and Vibration Control
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Solution Overview
Problem
Existing steering column assemblies face challenges in achieving higher stiffness of the bearing section while maintaining compatibility with conventional manufacturing methods, particularly in modern designs that require longer spindles and often result in increased weight or cost.
Innovation Solution
A steering spindle design featuring a hollow outer tube and inner tube, where the inner tube is press-fit into the outer tube, with specific geometrical configurations such as a lengthening section, attachment section, transition portion, and connection portion, allowing for increased natural frequency and stiffness without the need for non-traditional materials or excessive weight, achieved through metal construction and specific dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the spindle length is increased to meet modern design requirements, then the steering column assembly can accommodate longer steering wheels and improve ergonomics, but the stiffness of the bearing section decreases and natural frequency reduces
Solution Approach 1:
The spindle is divided into multiple sections with different outer diameters: a first section with a larger outer diameter for strength, a second section with a smaller outer diameter for weight reduction, and a third section with an intermediate outer diameter. This segmentation allows the long spindle to maintain adequate stiffness in critical areas while reducing overall weight and cost.
Solution Approach 2:
Different sections of the spindle are given different local properties through varying outer diameters. The first section has maximum outer diameter for high stiffness where it is supported by bearings, the third section has intermediate diameter for transition zones, and the fourth section has minimum diameter for lightweight extensions. This local quality optimization resolves the contradiction between length and stiffness.
2Strength
If the outer diameter of the bearing section is increased to提高 stiffness, then the natural frequency increases, but the weight and manufacturing cost increase
Solution Approach 1:
The spindle is segmented into sections with optimized outer diameters, so that only the critical bearing support sections have large diameters for stiffness, while other sections have smaller diameters to reduce weight. This avoids the need to increase the diameter of the entire spindle length.
Solution Approach 2:
The spindle structure is optimized with local quality variations where each section's outer diameter is specifically tailored to its functional requirements, achieving high stiffness where needed without proportionally increasing overall weight.
3Strength
If non-traditional materials or complex structures are used to increase stiffness, then the natural frequency improves, but the manufacturing cost and complexity increase
Solution Approach 1:
The spindle is divided into multiple sections with different outer diameters that can be manufactured using conventional processes. Each section can be produced separately and then joined using standard welding or other conventional joining methods, avoiding the need for complex non-traditional manufacturing processes.
Solution Approach 2:
The invention achieves stiffness improvement by changing geometric parameters (outer diameters of different sections) rather than changing material properties. This allows the use of conventional materials and manufacturing processes while still achieving the desired natural frequency and stiffness characteristics.
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 enhances the natural frequency and stiffness of the steering spindle, minimizing vibration transmission and improving the driving experience by maintaining high performance without the drawbacks of increased weight or cost, while being manufacturable using conventional methods.
Implementation Method 1
a hollow inner tube press-fit into the outer tube
Data Source
Figure 1
Figure 2
AI summary
One steering column assembly (100) includes a jacket (110), a bearing (115), and a steering spindle (120) rotatably supported by the bearing (115) and at least partially extending inside the jacket (110). The spindle (120) includes a hollow outer tube (122) and a hollow inner tube (142). The outer tube (122) has lengthening and attachment sections (123, 133), and the attachment section (133) has transition and connection portions (135, 137). The lengthening section (123) adjoins the attachment section (133) at an end (135a) of the transition portion (135), and the transition portion (135) is between the lengthening section (123) and the connection portion (137). The lengthening section (123) has first and second portions (123, 126), with the second portion (126) being between the first and transition portions (124, 135), and the outer tube (122) terminates at an end (137b) of the connection portion (137). The inner tube (142) is press- fit into the outer tube (122), and an end (142b) of the inner tube (142) is adjacent the transition portion end (135a). The inner tube (142) does not extend into either the attachment section (133) or the first portion (124).