Dual-Pinion Steering Pressing Member Rigidity
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Solution Overview
Problem
In dual-pinion electric power steering devices, achieving high accuracy in the alignment of rack teeth with pinion shafts is challenging, leading to misalignment and impaired steering smoothness due to the large load applied to the rack and pinion on the motor side.
Innovation Solution
A dual-pinion electric power steering device design featuring a first pressing member with lower rigidity than the second pressing member, made of materials like aluminum for the steering wheel side and iron for the rotational driving source side, to absorb misalignment and maintain steering smoothness, with bifurcated portions having different outside diameters to achieve optimal rigidity and manufacturing cost efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rack shaft is pressed firmly against the pinion shaft to maintain alignment, then the meshing accuracy is improved, but the rigidity of the pressing member increases which prevents absorption of misalignment
Solution Approach 1:
The patent applies different rigidity levels to different pressing members based on their local functional requirements. The first pressing member (steering shaft side) has lower rigidity to absorb misalignment, while the second pressing member (motor side) has higher rigidity to maintain firm meshing under large loads. This local differentiation of material properties resolves the contradiction between alignment accuracy and misalignment absorption.
Solution Approach 2:
The patent changes the rigidity parameter of the pressing members to resolve the contradiction. By selecting materials with different rigidity values for the first and second pressing members, the system can simultaneously achieve firm meshing where needed and misalignment absorption where needed, transforming a binary rigid/flexible choice into a differentiated parameter optimization.
2Stability of the object's composition
If high rigidity material is used for both pressing members to ensure stability, then the structural stability is improved, but the ability to absorb misalignment is reduced
Solution Approach 1:
The patent applies different rigidity levels to different pressing members based on their local functional requirements. The first pressing member (steering shaft side) has lower rigidity to absorb misalignment, while the second pressing member (motor side) has higher rigidity to maintain firm meshing under large loads. This local differentiation of material properties resolves the contradiction between alignment accuracy and misalignment absorption.
Solution Approach 2:
The patent changes the rigidity parameter of the pressing members to resolve the contradiction. By selecting materials with different rigidity values for the first and second pressing members, the system can simultaneously achieve firm meshing where needed and misalignment absorption where needed, transforming a binary rigid/flexible choice into a differentiated parameter optimization.
3Ease of manufacture
If the same material is used for both pressing members to simplify manufacturing, then the ease of manufacture is improved, but the ability to differentially absorb misalignment is lost
Solution Approach 1:
The patent applies different rigidity levels to different pressing members based on their local functional requirements. The first pressing member (steering shaft side) has lower rigidity to absorb misalignment, while the second pressing member (motor side) has higher rigidity to maintain firm meshing under large loads. This local differentiation of material properties resolves the contradiction between alignment accuracy and misalignment absorption.
Solution Approach 2:
The patent changes the rigidity parameter of the pressing members to resolve the contradiction. By selecting materials with different rigidity values for the first and second pressing members, the system can simultaneously achieve firm meshing where needed and misalignment absorption where needed, transforming a binary rigid/flexible choice into a differentiated parameter optimization.
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 effectively absorbs misalignment between rack teeth and pinions on the steering wheel side, maintaining smooth steering operation while allowing for cost-effective material selection and manufacturing.
Implementation Method 1
the first pressing member is formed to have a lower rigidity than the second pressing member, so that the misalignment occurring in the rack and pinion on the steering wheel side can be absorbed
Data Source
AI summary
A dual-pinion electric power steering device has: a rack shaft that causes a turnable member to turn; a first pinion shaft to which a steering force from a steering wheel is transmitted; a first rack teeth disposed on the rack shaft and capable of meshing with the first pinion shaft; a second pinion shaft to which a rotational driving force from an assist motor is transmitted; a second rack teeth disposed on the rack shaft and capable of meshing with the second pinion shaft; a first pressing member disposed across the rack shaft from the first pinion shaft and configured to press the rack shaft toward the first pinion shaft; and a second pressing member disposed across the rack shaft from the second pinion shaft and configured to press the rack shaft toward the second pinion shaft. The first pressing member has a lower rigidity than the second pressing member.