Tripod CV Joint Ball-Array Bearing for Low-Friction Compactness
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Solution Overview
Problem
Existing tripod constant velocity joints face challenges in achieving a compact size while reducing internal friction, which is crucial for improved NVH performance and fitting within limited vehicle spaces.
Innovation Solution
The tripod constant velocity joint design incorporates multiple ball arrays positioned at different radial locations, featuring track grooves and ball grooves with specific dimensions and configurations to allow ball circulation and minimize friction, along with a retainer to prevent escape and collision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional roller unit with outer and inner rollers and needle bearing is used, then the joint can transmit power, but the internal friction is high and the size is large
Solution Approach 1:
The bearing unit is segmented into multiple ball arrays (first, second, and third ball arrays) positioned at different radial locations, allowing each array to independently reduce friction at its contact point with the journal, thereby collectively reducing overall internal friction while maintaining power transmission
Solution Approach 2:
The conventional roller unit with multiple rollers and needle bearings is replaced with a simplified ball array system where balls directly contact the journal surface, eliminating the complex roller and needle bearing structure while achieving lower friction through point contact mechanics
2Volume of moving object
If the joint size is reduced to fit limited vehicle space, then compactness is improved, but internal friction increases due to tighter tolerances
Solution Approach 1:
Multiple ball arrays are arranged at different radial locations (different dimensions) around the journal, allowing the bearing unit to maintain effective friction-reducing contact across varying operational conditions while fitting within a compact overall size, as the distributed ball arrays provide redundancy and adaptability
Solution Approach 2:
Each ball array is positioned at a specific radial location to optimize local contact conditions with the journal, creating zones of reduced friction at critical points while maintaining overall compact dimensions, allowing different regions of the bearing unit to have specialized friction-reducing properties
3Loss of energy
If multiple ball arrays are added to reduce friction, then internal friction decreases, but the device complexity increases
Solution Approach 1:
The multiple ball arrays serve multiple functions simultaneously: they reduce friction through point contact, accommodate radial misalignments, compensate for manufacturing tolerances, and maintain compact size, thereby reducing friction without proportionally increasing complexity as each component serves several purposes
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 achieves a compact size with reduced internal friction, enhancing NVH performance and stability during operation.
Implementation Method 1
a first and a second ball array that are disposed between a peripheral surface of the track race and power transmission surfaces facing each other in a circumferential direction to form the track grooves and respectively comprise a plurality of balls
Data Source
AI summary
A tripod constant velocity joint according to an embodiment of the present invention includes: a housing having a tubular shape that forms three track grooves arranged along a circumferential direction; a spider having a hub placed inside the housing and three journals respectively extending radially outward from the hub and respectively arranged in the track grooves; and three bearing units respectively engaged to the journals. Each of the bearing units comprises a track race that is arranged in the track groove in a state of being tiltably engaged to the journal and a first and a second ball array that are disposed between a peripheral surface of the track race and power transmission surfaces facing each other in a circumferential direction to form the track grooves and respectively comprise a plurality of balls. The first and second ball arrays are arranged at different positions along a length direction of the journal.