Worm Wheel Reducer for Electric Power Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric power steering reducers experience reduced durability and increased vibration and noise due to the engagement of the worm shaft, worm wheel, and steering shaft, which are exacerbated by high-energy power transfer, leading to discomfort and potential component damage.
Innovation Solution
The reducer incorporates a worm wheel with a ring-shaped hub, teeth-shaped part, and insert ring, featuring gear teeth and support protrusions, and a boss integrally injection-molded with glass fiber-reinforced polyamide resin, enhancing mechanical strength and durability by improving coupling and separation strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional worm wheel structure is used, then the reducer can transfer power from the worm shaft to the steering shaft, but the durability decreases and vibration and noise increase due to engagement issues under high-energy power transfer
Solution Approach 1:
The worm wheel is constructed as a composite structure consisting of a hub, a teeth-shaped part, and an insert ring made of different materials. The insert ring is inserted into the hub and the teeth-shaped part is formed on the outer peripheral side of the hub, creating a multi-material composite component that improves durability and reduces vibration and noise during power transfer
Solution Approach 2:
The worm wheel is divided into multiple functional segments: a hub portion, a teeth-shaped part with gear teeth, and an insert ring with support protrusions. This segmentation allows each part to be optimized independently for its specific function while working together to reduce vibration and noise during engagement
2Power
If high-energy electric power is transferred through the worm wheel, then the steering assistance is improved, but the mechanical strength requirement increases and component damage may occur
Solution Approach 1:
The composite structure with insert ring and teeth-shaped part distributes the mechanical stress across different materials and structural elements, enabling the worm wheel to withstand high-energy power transfer from the motor while maintaining adequate mechanical strength
Solution Approach 2:
The insert ring is pre-installed into the hub before the teeth-shaped part is formed, creating a pre-assembled composite structure that is then engaged with the worm shaft, allowing the structure to be prepared in advance for high-power transfer conditions
3Ease of manufacture
If the worm wheel structure is simplified for ease of manufacture, then production cost decreases, but formability and accuracy of the worm wheel deteriorate
Solution Approach 1:
The worm wheel is segmented into a hub, insert ring, and teeth-shaped part that can be manufactured separately using different processes optimized for each component, then assembled together to achieve high precision and good formability without requiring complex single-step manufacturing
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 design enhances the formability, accuracy, and durability of the worm wheel, allowing stable long-term use under high-energy power transfer, reducing vibration and noise, and improving the overall steering experience.
Implementation Method 1
a boss which is integrally injection-molded between the outer peripheral side of the hub and the inner peripheral side of the teeth-shaped part
Data Source
AI summary
A reducer of an electric power steering apparatus comprises a worm wheel and a worm shaft connected to a motor shaft, the worm wheel and the worm shaft being engaged with each. The worm wheel includes: a ring-shaped hub into which the steering shaft is inserted and having a plurality of outer protrusions formed on the outer peripheral side thereof; a teeth-shaped part, engaged with the worm shaft and formed on the outer peripheral surface thereof, and inner protrusions, formed on the inner peripheral surface thereof, protruding in a radial direction, and formed in the circumferential direction; a ring-shaped insert ring inserted into the inner side of the teeth-shaped part and having support protrusions formed on the outer peripheral side thereof; and a boss integrally injection-molded between the outer peripheral side of the hub and the inner peripheral side of the teeth-shaped part.