Fixed-Type CVJ Track Groove Segmentation for Torque Loss
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Solution Overview
Problem
Existing fixed type constant velocity universal joints face challenges in suppressing torque loss and heat generation, especially at high operating angles, and struggle with durability and strength, due to insufficient effective track length and imbalance in pocket loads.
Innovation Solution
The design incorporates track grooves that cross each other in a peripheral direction, with arc-shaped first track groove portions having a curvature center aligned with the joint center and second track groove portions formed differently to increase effective track length, along with a specific pocket clearance to achieve both interference and clearance fits, stabilizing the cage and reducing friction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the curvature center of the track groove is offset to increase the operating angle, then the maximum operating angle is improved, but the effective track length becomes insufficient causing torque transmission failure
Solution Approach 1:
The track groove is divided into two distinct portions: a first track groove portion with a curvature center offset from the joint center to maximize operating angle, and a second track groove portion with a curvature center at the joint center to provide sufficient effective track length for torque transmission. This segmentation allows each portion to fulfill its specific function optimally.
Solution Approach 2:
Different portions of the track groove are given different curvature center positions tailored to their specific functional requirements. The first portion (for high operating angles) has an offset curvature center, while the second portion (for torque transmission) has a centered curvature center, creating local optimization throughout the groove structure.
2Ease of operation
If the cage and ball are fitted with an interference fit to suppress deterioration in bending operability, then the bending operability is improved, but torque loss and heat generation increase
Solution Approach 1:
The fit type between the cage and ball is changed from interference fit to clearance fit, altering the physical parameter of the connection. This parameter change reduces friction and torque loss while maintaining sufficient bending operability through the clearance configuration.
3Adaptability or versatility
If a large inlet chamfer is formed to increase the operating angle, then the maximum operating angle is improved, but the effective track length becomes insufficient causing ball drop-off
Solution Approach 1:
The track groove is segmented into two portions with different curvature characteristics. The first portion accommodates high operating angles while the second portion ensures reliable torque transmission by preventing ball drop-off through its centered curvature design, thus maintaining reliability.
4Volume of moving object
If the joint is designed to be compact and efficient, then the size is reduced, but the strength and durability at high operating angles deteriorate
Solution Approach 1:
The track groove is divided into two functional portions: the first portion optimized for high operating angles and the second portion optimized for torque transmission and structural strength. This segmentation allows the joint to maintain compact size while achieving both high operating angle capability and sufficient strength/durability.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3c
AI summary
Provided is a fixed type constant velocity universal joint, in which track grooves of an outer joint member include: first track groove portions positioned on an interior side; and second track groove portions positioned on an opening side. Each of the first track groove portions includes an arc part having a curvature center that is positioned without being offset in an axial direction with respect to a joint center. The first track groove portions are inclined in a peripheral direction of the outer joint member with respect to a joint axial line and adjacent to each other in the peripheral direction with their inclination directions opposite to each other. Each of the second track groove portions is formed into a different shape from a shape of the each of the first track groove portions so as to increase an effective track length at a maximum operating angle. The each of the first track groove portions and the each of the second track groove portions are connected to each other at a position on the opening side with respect to the joint center. Track grooves of the inner joint member are formed so as to be mirror-image symmetrical with corresponding paired track grooves of the outer joint member with respect to a plane including the joint center at an operating angle of 0°. A pocket clearance is set within a range in which balls and pockets of a cage are fitted with both an interference fit and a clearance fit.