Eccentric Rack Bushing Support for Steering Rattle Reduction
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Solution Overview
Problem
Conventional rack supporting devices in vehicle steering systems experience rattle noise due to gaps between the steering gear and rack bar, which are exacerbated by external forces and wear, leading to compromised steering performance.
Innovation Solution
A wedge-shaped rack bushing eccentric with the axis of the rack bar is used, supported by a spring and installed between the steering housing and rack bar, ensuring continuous engagement without gaps, utilizing a tapered passage and an elastic member to prevent rattle noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fastening force and fastening depth of the yoke plug are increased to reduce the gap between the yoke and yoke plug, then the rattle noise is reduced, but the steering performance deteriorates due to increased frictional force
Solution Approach 1:
The invention extracts the rattle noise reduction function from the yoke plug fastening system and relocates it to the rack bushing structure. The rack bushing with tapered bore and elastic member provides gap compensation between the rack bar and steering gear, separating this function from the yoke plug's primary fastening role, thereby avoiding increased frictional force on steering operation.
Solution Approach 2:
The rack bushing acts as an intermediary component between the rack bar and steering gear. Its tapered bore and elastic member create a self-adjusting mechanism that maintains constant engagement without requiring increased fastening force, thus eliminating rattle noise while preserving smooth steering operation.
2Reliability
If the frictional force between the rack bar and yoke sheet is increased to prevent rattle noise, then the engagement is improved, but the steering feel becomes rough
Solution Approach 1:
The rack bushing serves as an intermediary that provides reliable engagement through its tapered bore structure and elastic member, maintaining constant contact between the rack bar and steering gear without requiring increased frictional force from the yoke sheet, thus preserving smooth steering feel.
Solution Approach 2:
The invention changes the engagement mechanism from friction-based (increasing frictional force) to geometry-based (tapered bore shape). The tapered configuration with elastic member provides self-adjusting constant engagement, achieving reliability without compromising steering feel.
3Manufacturing precision
If the yoke plug fastening is strengthened to reduce gaps, then the initial engagement is improved, but wear increases causing gap recurrence
Solution Approach 1:
The invention extracts the gap compensation function from the fastening system and assigns it to the rack bushing with its tapered bore and elastic member. This separates the engagement maintenance function from the fastening system, reducing wear on the yoke plug and rack bar while maintaining precise engagement over time.
Solution Approach 2:
The rack bushing employs a dynamic self-adjusting mechanism through its elastic member and tapered bore. This allows the system to automatically compensate for wear and maintain constant engagement without requiring increased fastening force, thereby improving durability while maintaining manufacturing precision.
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 effectively prevents rattle noise by maintaining constant contact between the rack bushing and steering gear, even under external forces, while reducing the number of components and weight, and eliminating the need for a yoke mounting tube, enhancing packaging efficiency.
Implementation Method 1
an elastic member mounted to one side of the tapered passage to provide an elastic pressing force for pushing the rack bar to the rack bushing
Implementation Method 2
a tapered passage defined in an inner circumference of the steering housing... a rack bushing inserted between an inner circumference of the tapered passage and an outer circumference of the rack bar so that the rack bushing moves along the tapered passage and pushes the rack bar to the steering gear
Data Source
AI summary
A rack supporting device for vehicle steering systems includes: a steering housing having a steering gear installed therein; a rack bar longitudinally inserted into the steering housing to engage with the steering gear; a tapered passage defined in an inner circumference of the steering housing, wherein the tapered passage is eccentric with an axial center of the steering housing; a rack bushing inserted between an inner circumference of the tapered passage and an outer circumference of the rack bar so that the rack bushing moves along the tapered passage and pushes the rack bar to the steering gear; and an elastic member mounted to one side of the tapered passage to provide an elastic pressing force for pushing the rack bar to the rack bushing.