Steering Rack Bush Load Distribution and Noise Reduction
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Solution Overview
Problem
The existing rack bush and rack pinion type steering apparatus fail to smoothly support loads in the axial and vertical directions of the rack bar, leading to abnormal abrasion, rattle noise, and damage due to external impacts.
Innovation Solution
A rack bush with a hollow pipe-shaped bush body featuring multiple decreasing outer diameters, misaligned slits, and an annular elastic member, which provides rigidity and elastic deformation to distribute loads effectively, reducing noise and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rack bush structure is used to support the rack bar, then the structure is simple, but the load cannot be smoothly supported leading to abnormal abrasion and noise
Solution Approach 1:
The rack bush is divided into multiple sections along its length, with each section having different outer diameters formed by stepped portions. This segmentation allows different sections to perform different functions: some sections provide larger support area for load distribution, while others provide clearance for elastic deformation, thereby smoothly supporting axial and vertical loads without excessive complexity
Solution Approach 2:
Different sections of the rack bush are designed with different local qualities through varying outer diameters. The first section has a larger outer diameter for rigid support and load distribution, while the second section has a smaller outer diameter allowing elastic deformation. This local quality differentiation enables the rack bush to simultaneously provide structural support and noise reduction without overall complexity increase
2Object-generated harmful factors
If a rigid rack bush structure is used, then structural strength is maintained, but rattle noise occurs due to external force transfer
Solution Approach 1:
The rack bush transitions from a completely rigid structure to a dynamic structure with controlled flexibility. The second section with smaller outer diameter and elastic member allows the rack bush to dynamically adapt to external forces by deforming elastically, absorbing impact energy, and reducing rattle noise while the first section with larger outer diameter maintains overall structural strength
3Reliability
If the rack bush directly supports axial and vertical loads, then load support is provided, but abnormal abrasion occurs in the rack bush
Solution Approach 1:
The elastic member is pre-installed in the second section of the rack bush to provide preliminary cushioning capability. Before external loads are applied, the elastic member is already in position to absorb and distribute axial and vertical forces, preventing direct transmission of concentrated loads that would cause abnormal abrasion and extending the rack bush service life
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 solution enables smooth load support, reduces rattle noise, and prevents damage to the rack bar and pinion by distributing external impacts, enhancing the durability and performance of the steering apparatus.
Implementation Method 1
an elastic member having an annular shape and being in close contact with the outer peripheral surface of the bush body
Data Source
AI summary
Disclosed is a rack bush and a rack pinion type steering apparatus having the rack bush for a vehicle, which can smoothly support a load in an axial direction and a vertical direction of a rack bar so that it is possible to reduce abnormal abrasion of the rack bush, reduce a rattle noise caused by external force transferred through the rack bar during movement of the rack bar, and prevent damage to the rack bar and a pinion through distribution of the load due to an external impact on the shaft.