Worm Reducer Lead Angle Optimization for EPS
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional worm reducers for electric power steering systems face challenges in increasing the strength of both the worm and worm wheel while maintaining a reversely operable structure and reducing size, with issues related to meshing contact area, face pressure, and interference due to limitations in lead angles and material strength.
Innovation Solution
A worm reducer design featuring a worm with a smaller lead angle and a machining electro-deposition worm wheel with abrasive grains, where the worm wheel teeth are formed to match the lead angles of the worm, allowing for increased module and reduced center distance, and using a machining electro-deposition process to enhance strength and prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the diameter of the hob-cutter is increased to increase the meshing contact area, then the face pressure is reduced, but the cutting blades become weaker and may be broken
Solution Approach 1:
The patent changes the lead angle parameter of the hob-cutter to be smaller than that of the worm, which allows the hob-cutter to have sufficient strength while still achieving adequate meshing contact area through the optimized geometric parameters of the worm wheel teeth
Solution Approach 2:
The patent applies different lead angles to different components: the worm maintains its original lead angle while the hob-cutter uses a smaller lead angle, allowing each component to be optimized for its specific function (strength vs. meshing contact)
2Strength
If the diameter of the worm is increased to increase its strength, then the worm strength is improved, but it becomes difficult to maintain the predetermined wheel diameter of the worm wheel and lead angle of the reversely operable worm
Solution Approach 1:
The patent optimizes the module parameter of the worm wheel teeth and the center distance between worm and worm wheel to achieve the desired worm strength while maintaining compatibility with the worm wheel dimensions and lead angle requirements
Solution Approach 2:
The patent increases the module of the worm wheel teeth locally to enhance the overall system strength without increasing the worm diameter, allowing the worm to maintain its original dimensions and lead angle
3Reliability
If the lead angle of the worm wheel is made smaller than that of the worm, then interference is prevented and meshing contact is improved, but the conventional design with equal lead angles provides larger meshing contact area
Solution Approach 1:
The patent optimizes the geometric parameters including the smaller lead angle of the worm wheel, the module of the teeth, and the center distance to achieve adequate meshing contact area while preventing interference through the lead angle difference
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 strength and durability of the worm reducer, prevents life reduction, and allows for downsizing, improving transmission efficiency and flexibility in device layout while maintaining high endurance and abrasion resistance.
Implementation Method 1
a machining electro-deposition worm wheel with abrasive grains, where the worm wheel teeth are formed to match the lead angles of the worm, allowing for increased module and reduced center distance, and using a machining electro-deposition process to enhance strength and prevent interference
Data Source
AI summary
In a worm reducer for reducing the rotation transmitted to a worm and transmitting the reduced rotation to a worm wheel, the worm reducer being composed of the worm with screw faces formed on its outer periphery and the worm wheel with worm wheel teeth formed on its peripheral surface, the worm wheel teeth being in mesh with the screw faces of the worm, the worm wheel teeth are formed so that the lead angle of the worm wheel is smaller than that of the worm.