Cross-Track Fixed CV Joint Geometry for Large Operating Angles
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Solution Overview
Problem
Fixed type constant velocity universal joints with maximum operating angles greater than 50° face issues with ball contact loss, leading to reduced constant velocity characteristics, transmission efficiency, and durability due to disturbed force balances and increased load on specific balls, resulting in potential damage to joint members.
Innovation Solution
A cross track groove type design where the outer joint member's track grooves have arc-shaped portions with no axial offset and opposite inclination directions, and the inner joint member's track grooves are mirror-symmetric, allowing balls to maintain contact and balance forces even at large operating angles, preventing cage displacement and internal force imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the outer joint member length is shortened to prevent interference at large operating angles, then the maximum operating angle can be increased beyond 50°, but the track grooves become shorter causing balls to lose contact
Solution Approach 1:
The track grooves are designed with arc-shaped portions having specific curvature radii. The outer joint member's track grooves have arc-shaped portions with curvature radii of 3-6mm, while the inner joint member's track grooves have arc-shaped portions with curvature radii of 1.5-3mm. This curvature design allows balls to maintain proper contact even when the outer joint member length is shortened for large operating angles, resolving the contradiction between increased operating angle and reliable ball contact.
2Adaptability or versatility
If the track groove length is reduced due to shortened outer joint member, then large operating angles are enabled, but force balance is disturbed and specific balls bear excessive load
Solution Approach 1:
The arc-shaped portions in the track grooves create optimized force distribution paths. By carefully controlling the curvature radii (3-6mm for outer joint, 1.5-3mm for inner joint), the design ensures that even with shortened track grooves, the forces are distributed evenly across all balls, preventing any single ball from bearing excessive load and maintaining joint member durability at large operating angles.
Solution Approach 2:
The invention changes the geometric parameters of the track grooves by introducing arc-shaped portions with specific curvature radii. This parameter modification allows the system to achieve both large operating angles and balanced force distribution, as the curved geometry optimizes the mechanical advantage and load sharing among the torque transmission balls.
3Ease of manufacture
If conventional track groove designs are used at large operating angles, then manufacturing is simpler, but constant velocity characteristics and transmission efficiency are reduced
Solution Approach 1:
While the arc-shaped track grooves with specific curvature radii require precise manufacturing, the invention provides clear geometric specifications that enable consistent production. The curvature-based design optimizes the transmission efficiency and constant velocity characteristics at large operating angles, as the spherical geometry naturally guides the balls through the optimal path for torque transmission, reducing slippage and improving efficiency despite the increased manufacturing precision requirements.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~4
AI summary
Provided is a fixed type constant velocity universal joint (1) in which a raceway center line (X) of a track groove (7) of an outer joint member (2) includes at least an arc-shaped portion having a curvature center that has no offset with respect to a joint center (O) in an axial direction, in which a plane (M) including the raceway center line (X) and the joint center (O) is inclined with respect to an axis (N-N) of the joint, and the track groove (7) is formed with such an inclination direction of the plane (M) that the track grooves (7) adjacent to each other in a circumferential direction are inclined in opposite directions, and in which a raceway center line (Y) of a track groove (9) of an inner joint member (3) is formed so as to be mirror-symmetric with the raceway center line (X) of the paired track groove (7) of the outer joint member (2) with a plane (P) including the joint center (O) and being orthogonal to the axis (N-N) of the joint in a state of an operating angle of 0° as a reference. When a large operating angle is taken, an operating angle (θ2) at which a torque transmission ball (4) loses a contact with the track groove (9) of the inner joint member (3) is larger than an operating angle (θ1) at which the torque transmission ball (4) loses a contact with the track groove (7) of the outer joint member (2).