Tripod CV Joint Roller Assembly for Low-Friction Articulation
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Solution Overview
Problem
The existing tripod constant-velocity joints experience increased friction and shuddering during sudden acceleration or braking due to non-linear movement of the outer ring, particularly at large articulation angles, which deteriorates NVH characteristics.
Innovation Solution
The design incorporates a roller assembly with a first and second ball array, where the first ball array is disposed in a ball track with a larger sectional area and the second ball array in a track with a smaller sectional area, both with ball diameters varying in size and groove depths to minimize friction, and the ball tracks are configured as truncated cones to facilitate smooth articulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a roller assembly with a single outer ring is used, then the structure is simple, but friction increases and shuddering occurs at large articulation angles
Solution Approach 1:
The roller assembly is segmented into two distinct arrays: a first array with balls and a second array with rollers. This segmentation allows each element to perform its specific function optimally - balls for minimizing friction at large articulation angles and rollers for maintaining linear movement - thereby resolving the contradiction between structural simplicity and performance.
Solution Approach 2:
Different elements within the roller assembly are assigned different local qualities and functions. The first array uses spherical balls with specific diameter variations suited for high-friction conditions, while the second array uses cylindrical rollers optimized for linear movement. This local differentiation resolves the contradiction by optimizing each component for its specific operational context.
2Adaptability or versatility
If the outer ring moves in a slanted state on the roller track, then articulation and axial displacement can occur simultaneously, but friction increases and NVH characteristics deteriorate
Solution Approach 1:
The roller assembly dynamically adapts its configuration based on operational conditions. The ball array and roller array work in complementary fashion, with the ball array becoming more active at large articulation angles to minimize friction, while the roller array maintains linear movement during axial displacement. This dynamic adaptation resolves the contradiction between versatility and friction reduction.
Solution Approach 2:
The invention changes the geometric parameters of the roller elements - using balls with varying diameters in the first array and cylindrical rollers in the second array. These parameter variations allow the assembly to maintain low friction across different articulation angles while preserving the capability for simultaneous articulation and axial displacement.
3Object-generated harmful factors
If ball diameters vary in size within the ball arrays, then friction is minimized at large articulation angles, but manufacturing complexity increases
Solution Approach 1:
The ball arrays use balls with locally optimized diameters - smaller balls positioned to contact at large articulation angles where friction reduction is most critical, and larger balls for other positions. This local quality differentiation minimizes friction forces while the systematic arrangement maintains manufacturability.
Solution Approach 2:
The invention systematically varies ball diameter as a parameter across different positions in the array, with smaller diameters strategically placed for high-friction conditions. This controlled parameter change achieves friction minimization while maintaining manufacturing feasibility through standardized production processes.
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 configuration reduces friction forces at large articulation angles, minimizing shuddering and improving NVH characteristics by using spherical balls instead of ring-shaped members, allowing for efficient power transmission while preventing component breakage.
Implementation Method 1
the roller assembly coupled to the journal undergoes rolling in a roller track of the outer joint member to minimize a friction loss
Implementation Method 2
This configuration reduces friction forces at large articulation angles, minimizing shuddering and improving NVH characteristics by using spherical balls instead of ring-shaped members
Data Source
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AI summary
A tripod constant-velocity joint includes: an outer joint member having a cavity elongated in a longitudinal direction and three roller tracks; an inner joint member having a center body and three journals outwardly radially protruded from the center body; and three roller assemblies respectively coupled to the journal in a state of being respectively disposed in the roller tracks. The respective roller assembly comprises: an inner race which is connected to the journal and is provided with a first inner ball groove and a second inner ball groove on both lateral sides thereof; a first ball array and a second ball array respectively having a plurality of balls which are respectively disposed in the first inner ball groove and in the second inner ball groove; and a ball cage which restricts movements of the first ball array and the second ball array in a longitudinal direction thereof.