Tripod CV Joint Roller Constraint for Low-Friction Articulation
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Solution Overview
Problem
Existing constant velocity joints in motor vehicle transmission systems face issues with high friction and the risk of roller jamming, particularly at articulated angles, and are often complex and costly to manufacture.
Innovation Solution
The design incorporates a male and female element with specific track and rolling surface geometries, including oblique tangent planes and convex braking surfaces, along with a mechanical transmission unit featuring an inner ring and support rings, to reduce friction and prevent roller jamming, while maintaining ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional track and rolling surface geometries are used, then the joint structure is simpler, but friction is high and roller jamming risk increases at articulated angles
Solution Approach 1:
The rolling surface is designed with a spherical shape and the track with a toroidal shape, creating curved contact surfaces that maintain optimal contact geometry during articulation. This curvature ensures continuous point contact between the rolling surface and track, preventing roller jamming while reducing friction compared to conventional flat or cylindrical geometries.
2Reliability
If the rolling surface and track contact at multiple radial points, then friction is reduced and roller jamming is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies precise geometric parameters for the spherical rolling surface and toroidal track, including radius ratios and contact point positions. By carefully selecting these parameters, the design achieves multiple radial contact points that reduce friction while maintaining manufacturability through standardized geometric relationships rather than arbitrary complex shapes.
3Reliability
If the outer roller is constrained to prevent rotation around perpendicular axis, then transmission reliability improves, but the device complexity increases due to additional bearing surfaces
Solution Approach 1:
The bearing surface is integrated directly into the female element structure, combining the constraint function with the existing housing. The bearing surface prevents unwanted roller rotation around the perpendicular axis while maintaining a compact design, eliminating the need for separate constraint mechanisms and reducing overall device complexity.
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 achieves low friction, reduces the risk of roller jamming, and results in a durable, economical, and smooth-operating constant velocity joint with minimal shudder, facilitating efficient power transmission.
Implementation Method 1
an outer roller which is mounted so as to plunge and slide in relation to the arm and which is designed to roll on one or other of the corresponding two tracks via a peripheral rolling surface
Implementation Method 2
the female element furthermore comprising at least one bearing surface which prevents or limits the rotation of the outer roller around an axis perpendicular to the female element central axis
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This constant velocity joint (2) comprises a male element (4) having arms (8), a female element (16) having a central axis (X'-X') and defining a pair of symmetrical tracks (18, 20) and an outer roller (28) which is designed to roll on one or other of the two tracks (18, 20) via a peripheral rolling surface (52). The female element (16) comprises at least one bearing surface (60, 62) which limits the rotation of the outer roller (28) around an axis perpendicular to the axis' of the female element and of the arm (8). In respect of each arm (8) the cross-section profile of each track (18, 20) comprises either two circular arcs having centers of radii offset one from another or one single circular arc extending over a female element median plane (Q-Q) and the rolling surface (52) has as part spherical shape or a part torical shape. Each track (18, 20) and the rolling surface (52) are capable of contacting each other at a first and second contact points (Z1, Z2) spaced radially from one another. The tilting of the roller is controlled by proximal and distal rails on the female element (16) and by proximal and distal breaking surfaces on the outer roller (28).