Telescoping Shaft Groove Segmentation for Compact Packaging
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Solution Overview
Problem
Telescopic shaft assemblies in driveline systems face compactness limitations due to redundant rolling-element grooves, where only a fraction of grooves are functional, restricting packaging and increasing mass and rotational inertia, which affects fuel economy.
Innovation Solution
A rolling-element telescoping shaft assembly with all outer grooves functional, reducing the chordal distance between adjacent grooves, and optimized manufacturing processes to enhance compactness and reduce mass, allowing for cost-effective production and improved flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If redundant rolling-element grooves are added to the outer shaft member, then distortion during heat-treatment is minimized, but the chordal distance between functional grooves increases and packaging compactness is restricted
Solution Approach 1:
The outer shaft member is segmented into functional grooves and non-functional grooves (recesses). The non-functional grooves serve as heat-treatment relief features while the functional grooves transmit torque. This segmentation allows the outer shaft to achieve dimensional stability during heat-treatment without compromising the compact packaging of functional torque-transmitting grooves.
Solution Approach 2:
Non-functional grooves (recesses) are extracted from the torque-transmission function and dedicated solely to heat-treatment distortion control. By separating the heat-treatment relief function from the functional grooves, the design allows tighter spacing of functional grooves for compact packaging while maintaining outer shaft stability during heat-treatment.
2Volume of moving object
If the number of outer grooves is increased to reduce chordal distance, then packaging compactness is improved, but the web thickness between grooves decreases and structural strength is compromised
Solution Approach 1:
The groove system is segmented into functional and non-functional grooves. Non-functional recesses can be positioned to provide structural reinforcement between functional grooves, maintaining web thickness and strength while allowing functional grooves to be closely spaced for compact packaging.
Solution Approach 2:
Different regions of the outer shaft member have different properties: functional grooves have precise dimensions for torque transmission, while non-functional recesses can have varied dimensions optimized for both heat-treatment distortion control and local structural reinforcement. This local quality differentiation allows compact functional groove spacing without compromising overall structural integrity.
3Stability of the object's composition
If redundant grooves are used in the outer shaft member, then heat-treatment distortion is controlled, but manufacturing complexity and cost increase
Solution Approach 1:
The heat-treatment distortion control function is merged into the groove fabrication process itself. The same machining or forming operations that create functional grooves also create non-functional recesses, eliminating the need for separate heat-treatment distortion control features and reducing manufacturing complexity and cost.
Solution Approach 2:
Non-functional recesses serve multiple purposes: they provide heat-treatment distortion relief, can reinforce structural web thickness, and are created using the same manufacturing processes as functional grooves. This multi-functionality reduces the need for additional manufacturing steps and lowers overall production cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maximizes packaging compactness, reduces manufacturing costs, and enhances fuel economy by minimizing mass and rotational inertia while maintaining torque transmission efficiency.
Implementation Method 1
The rolling elements are configured to roll between the outer and inner shaft members during telescoping movement of the telescopic shaft assembly while continuing to transmit torque
Data Source
AI summary
A rolling-element telescoping shaft assembly for connecting a driveshaft and transmitting a torque includes an outer shaft member extending along a longitudinal axis and defines an interior bore and inner surface. An inner shaft member is at least partially disposed within the bore and telescopically moveable relative thereto along the axis and defines an outer surface. Rolling-element outer grooves are arranged in the inner surface, distributed around the axis, and functional (i.e., used for transmitting a torque). Outer recesses are defined between the outer grooves and define a shorter distance between adjacent torque-transmitting outer grooves. Rolling-element inner grooves are defined on the outer surface and distributed around the axis. Rolling elements are rollingly arranged in the outer and inner grooves and rollingly engage the outer and inner shaft members during telescoping movement of the shaft assembly to reduce friction therebetween.