Cross-Groove Constant Velocity Joint for Large-Angle Ball Contact
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Solution Overview
Problem
Existing fixed type constant velocity universal joints face challenges in maintaining constant velocity characteristics, transmission efficiency, and durability when operating at large angles greater than 50°, as the ball loses contact with the track groove, leading to disturbances in the balance of forces and reduced strength of the cage.
Innovation Solution
A cross track groove type design is implemented, where the outer joint member has track grooves with arc-shaped portions and linear portions connected smoothly, and the inner joint member has mirror-symmetric track grooves, allowing the ball to lose contact at a specific phase angle while maintaining balance and stability of the cage, thereby enhancing the operating angle and strength.
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 operating angle can be increased, but the track grooves become shorter causing the ball to lose contact
Solution Approach 1:
The track groove is designed with a curved profile where the curvature radius varies along the groove length. Specifically, the curvature radius is larger near the opening side and smaller near the closed side, creating a smooth transition that maintains ball contact even when the joint operates at large angles. This curvature design allows the ball to follow the groove path without disengaging, resolving the contact loss issue while enabling larger operating angles.
Solution Approach 2:
The invention changes the geometric parameters of the track groove, specifically the curvature radius as a function of position along the groove. By making the curvature radius variable rather than constant, and by optimizing specific dimensional parameters (such as the ratio of curvature radii at different positions), the design maintains reliable ball contact throughout the operating range while accommodating large operating angles greater than 50 degrees.
2Length of stationary object
If the pitch circle diameter of the balls is increased to elongate the track grooves, then the track groove length increases, but the outer diameter and weight of the outer joint member increase
Solution Approach 1:
Instead of increasing the ball pitch circle diameter to achieve longer track grooves, the invention changes the track groove geometry by varying its curvature radius along the length. This alternative parameter modification allows the groove to be effectively elongated in terms of ball contact path without requiring larger balls or a larger pitch circle diameter, thereby avoiding the weight penalty associated with increasing the outer joint member dimensions.
Solution Approach 2:
By designing the track groove with a specific curved profile where the curvature radius varies along the groove, the invention achieves an effective elongation of the contact path. The curved geometry allows the groove to accommodate a longer ball trajectory within the same outer joint member envelope, eliminating the need to increase the pitch circle diameter and thus preventing weight increase.
3Adaptability or versatility
If a combination of arc shape and tapered shape is used for track grooves to achieve large operating angle, then the operating angle increases, but the outer diameter of the outer joint member is increased
Solution Approach 1:
The invention uses a curved track groove profile with variable curvature radius instead of a combination of arc and tapered shapes. This single continuous curved design achieves the same large operating angle capability while being more space-efficient in the radial direction, thereby avoiding the increase in outer diameter that results from using separate arc and tapered sections.
Solution Approach 2:
By modifying the curvature radius parameter along the track groove length rather than using a composite shape with multiple geometric features, the invention achieves large operating angles without requiring increased outer diameter. The continuous parameter variation provides a more compact radial profile compared to the multi-segmented arc-tapered design.
Data Source
AI summary
A fixed type constant velocity universal joint has outer joint member track grooves each with a raceway center line that includes an arc-shaped portion having a curvature center that has no offset with respect to a joint center in an axial direction. The track grooves are formed such that adjacent track grooves are inclined in opposite directions. The joint also has inner joint member track grooves that are each mirror-symmetric with a corresponding one of the outer joint member track grooves. When at a maximum operating angle, a torque transmission ball that moves toward an opening side of the outer joint member track groove loses contact with an opening-side end portion of that track groove, and when at an operating angle of 0°, an end portion of a cage projects from the opening-side end portion of the outer joint member in the axial direction.