Plunging CV Joint Clearance Structure for High-Angle Durability
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Solution Overview
Problem
Existing plunging type constant velocity universal joints face challenges in reducing slide resistance and maintaining durability at high normal operating angles while ensuring stable constant velocity characteristics, particularly in electric vehicles and SUVs where increased operating angles are required.
Innovation Solution
A double-offset constant velocity universal joint design with a positive axial clearance between the cage pocket and torque transmission balls, featuring spherical surfaces with equal curvature radii and a spherical clearance for guide-in-contact configuration, reduces slide resistance and enhances durability by allowing smooth rolling and stable angular contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If axial clearance is secured between inner joint member and cage to reduce slide resistance, then slide resistance decreases, but constant velocity characteristics become unstable
Solution Approach 1:
The invention applies different clearance conditions to different locations: a first axial clearance (0.003mm to 0.030mm) between the inner joint member and cage to reduce slide resistance, and a second axial clearance (0.000mm to 0.005mm) between the cage and outer joint member to maintain constant velocity characteristics. This localized differentiation resolves the contradiction by optimizing each interface separately.
Solution Approach 2:
The invention changes the parameter of axial clearance from a single uniform value to two distinct values with different ranges. The first axial clearance is set larger (0.003mm to 0.030mm) for vibration damping and reduced slide resistance, while the second axial clearance is set smaller (0.000mm to 0.005mm) for stable constant velocity characteristics, thereby resolving the contradiction through parameter optimization.
2Adaptability or versatility
If normal operating angle is increased for SUV applications, then travel performance improves, but induced thrust increases causing horizontal oscillation
Solution Approach 1:
The invention optimizes the curvature radii parameters of the spherical surfaces to reduce induced thrust. Specifically, the curvature radius of the spherical outer peripheral surface of the inner joint member is set to 0.95 to 1.05 times the curvature radius of the spherical inner peripheral surface of the cage, which minimizes the third order component (induced thrust) even at increased normal operating angles of 8° or more.
Solution Approach 2:
The invention uses spherical surfaces with specifically optimized curvature radii for the inner joint member and cage. The curvature radius ratio of 0.95 to 1.05 ensures smooth rolling contact and minimizes induced thrust, allowing the joint to operate stably at higher normal operating angles required for SUV applications.
3Ease of manufacture
If curvature radii of spherical surfaces are made equal, then manufacturing simplicity improves, but guide-in-contact stability deteriorates
Solution Approach 1:
The invention optimizes the curvature radius ratio to 0.95 to 1.05, which is substantially equal for practical manufacturing purposes but provides sufficient guide-in-contact stability. This parameter optimization allows near-equal curvature radii to be used, simplifying manufacturing while maintaining reliable guide-in-contact performance.
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 achieves reduced slide resistance, improved durability, and stable constant velocity characteristics, even at high normal operating angles, with a rotational backlash of 15 minutes or less, enhancing torque load responsiveness and vibration damping in electric vehicles.
Implementation Method 1
A plurality of torque transmission balls (4) are individually interposed between a plurality of linear track grooves (7, 9)
Implementation Method 2
spherical surfaces with equal curvature radii and a spherical clearance for guide-in-contact configuration
Data Source
AI summary
A plunging type constant velocity universal joint includes an outer joint member having a plurality of linear track grooves, an inner joint member having a plurality of linear track grooves, a plurality of torque transmission balls, and a cage configured to accommodate the torque transmission balls in pockets. A curvature center of a spherical outer peripheral surface and a curvature center of a spherical inner peripheral surface of the cage are offset toward opposite sides in an axial direction with respect to a joint center. A spherical clearance that allows guide in contact is formed between a spherical outer peripheral surface of the inner joint member and a spherical inner peripheral surface of the cage. A positive axial clearance is formed between the pocket of the cage and the torque transmission ball.