Constant Velocity Joint Groove Geometry to Reduce Cage Friction
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Solution Overview
Problem
Existing constant velocity joints face challenges in restraining friction between the cage and the inner and outer joint members, especially at large joint angles, leading to mechanical losses during torque transmission.
Innovation Solution
A constant velocity joint design featuring an outer joint member with alternating first and second ball grooves and an inner joint member with corresponding grooves, where the cage includes window portions to accommodate the balls, ensuring that the force applied to the second ball is not reversed, thereby maintaining effective friction reduction across various joint angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the joint angle increases, then the range of motion is improved, but the friction between the cage and joint members increases due to force reversal
Solution Approach 1:
The patent applies asymmetry by configuring the second outer ball groove and second inner ball groove with specific curvature radii and orientations that are asymmetric relative to the joint center. The second outer ball groove has a curvature radius R2 and the second inner ball groove has a curvature radius r2, with their centers positioned asymmetrically to ensure the second open angle β maintains a constant direction (facing the bottom side) throughout the joint angle range. This asymmetric configuration prevents force reversal on the second ball, thereby reducing friction between the cage and joint members even at large joint angles.
2Stability of the object's composition
If the force direction on the second ball is reversed at large joint angles, then the mechanical balance is disrupted, but friction increases
Solution Approach 1:
The patent implements preliminary anti-action by pre-configuring the geometry of the second outer ball groove and second inner ball groove such that the second open angle β consistently faces the bottom side throughout the entire joint angle range. This pre-designed geometric arrangement anticipates and counteracts the potential force reversal that would occur at large joint angles in conventional designs. By establishing the correct force direction in advance through proper groove configuration, the patent prevents friction increase before it occurs.
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 design effectively reduces friction between the cage and the joint members even at large joint angles, minimizing mechanical losses during torque transmission and enhancing the performance of the joint, particularly in vehicle applications.
Implementation Method 1
The ball is rotatably supported by the rolling contact surface of the outer ball groove and the rolling contact surface of the inner ball groove, so as to transmit a torque between the outer joint member and the inner joint member
Implementation Method 2
frictions are caused between the cage and an inner peripheral surface of the outer joint member and between the cage and an outer peripheral surface of the inner joint member, thereby causing a mechanical loss
Data Source
AI summary
A joint-center-fixed constant velocity joint configured to be provided in a vehicle includes an outer joint member, an inner joint member, a first ball, a second ball, and a cage. While a center of the first ball is moving to a position of the maximum use angle on an opening side from a joint center, a first open angle faces the opening side. While a center of the second ball is moving to a position of the maximum use angle on a bottom side from the joint center, a second open angle is not reversed from a state where the second open angle faces the bottom side to a state where the second open angle faces the opening side.