MDPS Coupler Member Design for Axial Load and Noise Reduction
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Solution Overview
Problem
The existing motor-driven power steering (MDPS) systems face issues with durability, increased weight and manufacturing cost due to complex coupler structures, which lead to axial load changes causing rattle noise and reduced performance.
Innovation Solution
A simplified MDPS system design featuring a coupler member with a polygonal transverse cross-sectional surface and an elastic sleeve pressurizing part to securely couple the driving and worm shaft members, reducing noise and enhancing durability by minimizing part count and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a complex coupler structure with multiple dogs is used to couple the driving member and worm shaft member, then the coupling strength is improved, but the device complexity, weight, and manufacturing cost increase
Solution Approach 1:
The patent merges multiple separate dogs into a single integrated coupler member with a simplified structure. Instead of using multiple discrete coupling elements, the invention combines their functions into one unified component that couples the driving member and worm shaft member directly, thereby reducing device complexity and part count while maintaining coupling strength
Solution Approach 2:
The coupler member is designed to perform multiple functions simultaneously: it provides coupling between the driving member and worm shaft member, transmits rotational power, and maintains axial load. This multi-functional design eliminates the need for separate components for each function, reducing overall system complexity
2Strength
If a complex coupler structure with multiple dogs is used to couple the driving member and worm shaft member, then the coupling strength is improved, but the weight increases
Solution Approach 1:
By combining multiple dogs into a single coupler member, the total weight of the coupling system is reduced. The integrated design eliminates redundant material and reduces the overall mass of the coupler assembly while maintaining the necessary coupling strength through optimized geometry
3Power
If the coupler is repetitively exposed to load, then the power transmission function is maintained, but the coupler becomes permanently deformed and durability is reduced
Solution Approach 1:
The coupler member is designed with dynamic characteristics that allow it to flex and adapt under repetitive loading conditions. The structure incorporates elastic deformation capabilities and stress distribution features that prevent permanent deformation, enabling the coupler to maintain its power transmission function while withstanding repeated load cycles
Solution Approach 2:
The patent optimizes the material properties and geometric parameters of the coupler member to improve its durability under repetitive loading. By changing parameters such as material composition, cross-sectional geometry, and stress distribution characteristics, the coupler can withstand repetitive loads without permanent deformation
4Device complexity
If the coupler structure is simplified to reduce part count, then manufacturing cost and weight are reduced, but the durability and axial load capability may be compromised
Solution Approach 1:
The coupler member features local quality variations with different cross-sectional geometries along its length. The structure is thicker and more robust in regions subjected to higher stresses while being thinner in less critical areas. This localized optimization maintains durability and axial load capability while minimizing overall material usage and maintaining simplicity
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 improves durability, reduces noise, and maintains axial load, allowing for efficient power transmission and stable steering performance while simplifying assembly and maintenance.
Implementation Method 1
The sleeve pressurizing part may be formed in a ring shape including an elastic material, and seated on the outer circumferential surface of the couple sleeve part so as to pressurize the couple sleeve part toward the rotating shaft or the worm shaft member
Data Source
AI summary
A motor driven power steering (MDPS) system is disclosed. The MDPS system includes a driving member configured to rotate about an axis; a worm shaft member having a worm gear and configured to rotate while engaged with a worm wheel; and a coupler member interposed between the driving member and the worm shaft member and configured to couple the driving member and the worm shaft and transmit power from the driving member to the worm shaft member. The coupler member includes a couple sleeve portion configured to receive and hold the driving member and the worm shaft member and a sleeve pressurizing portion surrounding the couple sleeve portion and configured to pressurize the couple sleeve portion toward the driving member or the worm shaft member.