Rack Bar Support Yoke Composite Design for Steering Noise Reduction
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Solution Overview
Problem
Conventional rack bar supporting devices in steering apparatuses face issues with increased free movement and resulting noise due to wear in the support yoke, leading to reduced steering stability and discomfort, especially on uneven road surfaces.
Innovation Solution
The proposed solution involves a rack bar supporting device with a support yoke and sliders having slant surfaces, supported by elastic forces, which automatically adjust to maintain predetermined free movement and reduce noise by sliding radially along these surfaces, coupled with a yoke plug to stabilize the sliders and absorb impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the support yoke is made of plastic material softer than the rack bar to prevent wear and noise, then the wear resistance and noise reduction are improved, but the structural strength and durability are reduced leading to increased free movement
Solution Approach 1:
The support yoke is constructed as a composite structure combining a plastic material body (for noise reduction and wear resistance) with an embedded metal reinforcement member (for structural strength and durability). This composite design allows the soft plastic to absorb noise while the metal reinforcement prevents excessive free movement even after wear occurs.
Solution Approach 2:
The plastic material is strategically designed with varying local properties: softer regions contact the rack bar to reduce noise and wear, while harder reinforced regions (with embedded metal members) provide structural support and limit free movement. This local quality differentiation resolves the contradiction between noise reduction and maintaining reliability.
2Strength
If the support yoke is made softer to reduce friction and wear, then the wear resistance is improved, but the free movement increases due to wear degradation
Solution Approach 1:
The composite structure of soft plastic with embedded metal reinforcement allows the plastic to provide wear resistance through its softer surface, while the metal reinforcement maintains structural integrity and limits free movement even after the plastic wears down over time.
Solution Approach 2:
The embedded metal reinforcement members are pre-installed within the plastic support yoke to provide beforehand cushioning and structural support. When wear occurs in the plastic material, the metal reinforcement prevents excessive free movement from developing, effectively compensating for the wear degradation in advance.
3Force
If the support yoke slides against the rack bar to provide support, then the supporting function is improved, but friction causes wear and noise
Solution Approach 1:
The plastic material in the support yoke provides the necessary support force through its structural design while its softer nature reduces friction during sliding contact with the rack bar, thereby minimizing both wear and noise generation.
Solution Approach 2:
The plastic material is used uniformly throughout the support yoke structure to ensure consistent friction characteristics and noise reduction properties across all contact surfaces, while the embedded metal reinforcement provides homogeneous structural support throughout the component.
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
This configuration effectively prevents the increase in free movement and associated noise, enhancing steering stability and comfort by maintaining consistent contact between the rack bar and pinion gear, even under wear conditions and impact from uneven surfaces.
Implementation Method 1
support the support yoke in a front direction by an elastic force of radial-directionally supporting elastic supports coupled with separate surfaces of the sliders
Implementation Method 2
The spring 263 pushes the support yoke 260 at a predetermined pressure so as to compensate free-movement occurring between the rack bar 140 and the pinion gear 120
Data Source
AI summary
Disclosed is a rack bar supporting device of a rack and pinion type steering apparatus for a vehicle. The disclosed device can prevent free movement from increasing by automatically adjusting a predetermined free movement even when wear occurs in a support yoke after degradation of driving durability of the vehicle, and can prevent a noise from occurring caused by an increase of free movement when the support yoke collides with a yoke plug by an impact reversely input from an uneven road surface, etc. This can provide a comfortable steering feeling to the driver.