Constant Velocity Joint Ball Spline for Lighter Driveshaft Packaging

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Solution Overview

Problem

Existing constant velocity joints with ball spline structures face challenges such as increased diameter, weight, and manufacturing complexity, which affect vehicle design, fuel efficiency, and production costs.

Innovation Solution

A constant velocity joint design that incorporates a ball spline coupling structure between the inner race and interconnecting shaft, allowing for reduced diameter and weight, while enabling axial displacement and simplifying the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a ball spline structure is applied to the interconnecting shaft to enable axial displacement, then axial displacement capability is improved, but the shaft diameter increases by up to 60% and weight increases

Engineering Contradiction:

Improveaxial displacement capabilityVSAvoidinterconnecting shaft weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent divides the axial displacement function from the interconnecting shaft by introducing a separate ball spline coupling structure. The shaft is segmented into a shaft body and a coupling portion, where the coupling portion contains the ball spline mechanism while the shaft body maintains its original dimensions. This allows axial displacement capability without increasing the main shaft diameter.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a ball spline coupling structure as an intermediary mechanism between the inner race and the interconnecting shaft. This coupling structure includes guide grooves and balls that enable axial displacement without requiring the interconnecting shaft itself to have a large diameter, thus mediating between the need for axial movement and the constraint of shaft size.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a ball spline structure is applied to the interconnecting shaft to enable axial displacement, then axial displacement capability is improved, but the shaft diameter increases by up to 60%

Engineering Contradiction:

Improveaxial displacement capabilityVSAvoidinterconnecting shaft diameter

Core Design Contradiction:

Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The patent segments the interconnecting shaft into a shaft body and a coupling portion, allowing the coupling portion to contain the ball spline mechanism while the shaft body maintains its original smaller diameter. This segmentation enables axial displacement capability without increasing the main shaft diameter by up to 60%.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent moves the axial displacement mechanism from the radial dimension (shaft diameter) to the axial dimension (length of coupling portion). The ball spline structure achieves axial displacement through the length of the coupling portion rather than requiring increased shaft diameter, effectively using another dimension to solve the problem.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If a ball spline structure is applied to the interconnecting shaft, then axial displacement capability is improved, but the manufacturing process becomes more complex and production costs increase

Engineering Contradiction:

Improveaxial displacement capabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent segments the ball spline coupling structure into separate components including the shaft coupling portion, guide grooves, and balls. This segmentation allows each component to be manufactured independently using standard machining processes, reducing overall manufacturing complexity compared to integrating the entire ball spline mechanism into a single shaft component.

Inventive Principle:

Principle #1Segmentation

4Object-generated harmful factors

If a tripod constant velocity joint is used to minimize generated axial force, then GAF reduction is improved, but the structure becomes more complex and cost increases

Engineering Contradiction:

Improvegenerated axial forceVSAvoidjoint structure complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces a ball spline coupling structure as an intermediary mechanism between the inner race and the interconnecting shaft. This coupling structure includes guide grooves and balls that enable axial displacement without requiring the complex tripod joint design, thus reducing GAF while maintaining simpler structure and lower cost.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12601379B2Constant velocity joint and driveshaft including same

Publication Date: 2026.04.14 HANSAE MOBILITY CO LTD

AI summary

A constant velocity joint configured to be coupled to an interconnecting shaft includes: an outer race forming a plurality of outer ball tracks; an inner race forming a plurality of inner ball tracks; a ball cage interposed between the outer race and the inner race and forming a plurality of windows; and a plurality of torque transmitting balls. The outer race and the inner race are configured to implement an angular articulation function that allows for relative angular displacement therebetween, and the inner race is coupled to the interconnecting shaft via a ball spline coupling structure to implement a length displacement function. The ball spline coupling structure includes: an outer spline groove; an inner spline groove; a sleeve member interposed between the inner race and the interconnecting shaft; and a plurality of spline balls, with said spline balls being accommodated within a sleeve window formed on the sleeve member.