Tripod Constant Velocity Joint Polyhedral Trunnion Contact Distribution
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Solution Overview
Problem
Conventional constant velocity joints face issues with power transmission stability due to concentrated driving force, increased contact pressure, and excessive frictional force, leading to reduced durability and increased vibration in vehicles.
Innovation Solution
A tripod type constant velocity joint is designed with polyhedral trunnions having multiple polygonal surfaces that form multiple contact points with inner rollers, allowing for distributed power transmission and lubrication of limited relative movement areas to reduce friction and axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional constant velocity joints use single contact point between trunnion and inner roller, then the structure is simple, but power transmission stability deteriorates and contact pressure increases
Solution Approach 1:
The trunnion is designed with a polyhedral shape featuring multiple flat surfaces instead of a conventional cylindrical shape. This segmentation of the contact interface creates multiple discrete contact points between the trunnion and inner roller, distributing the driving force across several locations. The polyhedral geometry with surfaces at different orientations ensures that power transmission is stabilized by having multiple contact zones rather than a single concentrated contact point, thereby reducing contact pressure while maintaining reliability.
2Reliability
If conventional constant velocity joints use full surface contact between components, then power transmission is stable, but frictional force becomes excessively large
Solution Approach 1:
The polyhedral trunnion creates segmented contact points rather than continuous full-surface contact. Each flat surface of the polyhedral trunnion forms a distinct contact zone with the inner roller, and the gaps between these surfaces create non-contact regions. This segmentation maintains power transmission stability through multiple contact points while significantly reducing the total contact area compared to full surface contact, thereby minimizing frictional force and energy loss.
Solution Approach 2:
The inner roller is designed with a curved circumferential surface that contacts the flat surfaces of the polyhedral trunnion. This curvature allows the roller to smoothly engage with each flat surface of the trunnion while maintaining point or line contact rather than full surface contact. The curved geometry of the inner roller complements the polyhedral shape to achieve stable power transmission with reduced frictional resistance.
3Stress or pressure
If conventional constant velocity joints use polyhedral trunnion with multiple contact points, then contact pressure is distributed, but lubrication of limited relative movement areas becomes difficult
Solution Approach 1:
The polyhedral trunnion features flat surfaces with specific orientations that create localized contact zones. Each flat surface is designed to contact the inner roller at specific locations, creating areas of limited relative movement that can be selectively lubricated. The local geometry of each surface is optimized to maintain appropriate contact pressure distribution while allowing lubricant access to the contact interfaces through the segmented structure and gaps between surfaces.
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 ensures stable power transmission, prevents excessive friction and contact pressure, reduces vehicle vibration, and enhances durability by distributing contact points and providing adequate lubrication.
Implementation Method 1
a plurality of needle rollers assembled to a circumferential outer surface of each inner roller
Implementation Method 2
outer rollers each of which is installed on the circumferential outer surface of each inner roller to reduce friction between the housing and the shaft
Data Source
AI summary
A tripod type constant velocity joint comprises a housing having three track grooves defined at trisected positions of the housing and extending in an axial direction, and a spider having three -trunnions projectedly formed at trisected positions of the spider to be respectively inserted into the track grooves, each trunnion having a generally oval or elliptical cross-sectional shape and including at least one independent contact surface at each of two opposing sides subjecting to a load. Inner rollers each has an inner surface of a concavely curved contour for receiving a corresponding trunnion therein, and an outer roller is mounted to each inner roller with a plurality of needle rollers engaged there-between.