Fixed CVJ Track Groove Design for High Operating Angles
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Solution Overview
Problem
Existing fixed type constant velocity universal joints face challenges in achieving high operating angles while minimizing torque loss and heat generation, and maintaining strength and durability, particularly at frequently used operating angles.
Innovation Solution
The design incorporates track grooves that cross each other in the peripheral direction, with first track groove portions having arc-shaped ball raceway centers not offset axially and second track groove portions having straight parts for increased effective length at high angles, reducing wedge angles and enhancing cage strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the curvature center of the ball raceway center line is offset to the opening side to increase the maximum operating angle, then the maximum operating angle is improved, but the effective track length becomes insufficient causing balls to drop off
Solution Approach 1:
The track groove is divided into two distinct portions: a first track groove portion with an arc-shaped ball raceway center line for normal operating angles, and a second track groove portion with a straight ball raceway center line for high operating angles. This segmentation allows each portion to be optimized for its specific function, resolving the contradiction between maximum operating angle and effective track length.
Solution Approach 2:
The ball raceway center line transitions from an arc-shaped configuration to a straight configuration based on the operating angle requirements. The curved portion handles normal operations while the straight portion engages at high angles, providing dynamic adaptability that resolves the geometric conflict between angle capability and track length.
2Loss of energy
If track grooves cross each other in the peripheral direction to reduce torque loss and heat generation, then efficiency is improved, but the wedge angle increases reducing cage strength
Solution Approach 1:
The crossing angle of the track grooves is optimized locally rather than uniformly. The grooves are configured to cross at angles that minimize torque loss during normal operation, while the straight portions at high angles reduce the effective wedge angle to protect cage strength. This local optimization resolves the contradiction between efficiency and strength.
3Strength
If the straight part of the second track groove portion approaches the joint axial line to reduce wedge angle, then cage strength is improved, but the effective track length decreases
Solution Approach 1:
The track groove is segmented into arc-shaped and straight portions, each serving distinct functions. The straight portion is positioned to approach the joint axial line at high operating angles to reduce wedge angle and protect cage strength, while the arc-shaped portion provides sufficient effective track length during normal operation. This segmentation resolves the contradiction between strength and track length.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3c
AI summary
In a fixed type constant velocity universal joint (1), track grooves of an outer joint member include: first track groove portions (7a) positioned on an interior side; and second track groove portions (7b) positioned on an opening side. Each of the first track groove portions (7a) includes an arc-shaped ball raceway center line (Xa) having a curvature center prevented from being offset in an axial direction of the outer joint member with respect to a joint center (O). Planes (M) each including at least the ball raceway center line (Xa) and the joint center (O) are inclined with respect to a joint axial line (N-N) with their inclination directions opposite to each other in the first track groove portions (7a), which are adjacent to each other in a peripheral direction of the outer joint member. Each of the second track groove portions (7b) includes a ball raceway center line (Xb) having a straight part when being projected onto corresponding one of the planes (M). The straight part is formed in an inclined manner to approach the joint axial line (N-N) as a distance to the opening side becomes smaller. The ball raceway center line (Xa) of the each of the first track groove portions (7a) includes an end portion (A) positioned on the opening side in the axial direction with respect to the joint center (O). The ball raceway center line (Xb) of the each of the second track groove portions (7b) is connected to the end portion (A). Each of track grooves of an inner joint member includes a ball raceway center line (Y), which is formed so as to be mirror-image symmetrical with a ball raceway center line (X) of corresponding one of the paired track grooves of the outer joint member with respect to a plane (P) including the joint center (O) at an operating angle of 0°.