CFRP Drive Shaft Joint Structure for Reliable Steel Coupling
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Solution Overview
Problem
Current drive shafts in automobiles, made of steel, are heavy, leading to increased oil consumption and emissions, and existing lightweight carbon fiber reinforced plastic (CFRP) drive shaft designs face challenges in reliable dissimilar material connections and manufacturing complexity, particularly with universal joint forks and spline connections that fail under varying temperatures and torque loads.
Innovation Solution
A shaft-tube joint structure for a CFRP drive shaft featuring a CFRP hollow shaft tube with circumferentially arranged rectangular teeth, connected to steel universal joints via a nesting-meshing composite connection using structural adhesive, ensuring reliable dissimilar material bonding and improved torsion and bending resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If steel is used to manufacture drive shaft and universal joint forks, then strength and reliability are ensured, but weight increases leading to higher oil consumption and emissions
Solution Approach 1:
The patent applies composite materials by replacing traditional steel universal joint forks with CFRP (carbon fiber reinforced plastic) composite forks. The CFRP material provides high strength-to-weight ratio, reducing drive shaft weight while maintaining sufficient strength. The composite structure allows optimization of material distribution to achieve both lightweight and strong performance.
Solution Approach 2:
The patent changes material parameters by transitioning from homogeneous steel material to CFRP composite material with different physical and mechanical properties. This parameter change enables weight reduction while maintaining strength through the superior specific strength (strength-to-weight ratio) of CFRP compared to steel.
2Weight of moving object
If CFRP is used for shaft tube, then weight is reduced, but reliable connection with metal universal joint forks becomes difficult due to dissimilar material bonding challenges
Solution Approach 1:
The patent introduces an intermediary bonding mechanism through surface treatment and adhesive bonding systems that mediate between CFRP shaft tube and metal universal joint forks. The surface treatment (such as plasma treatment, sandblasting, or chemical etching) creates a transition zone that enhances adhesion, while the adhesive layer acts as a mediator to transfer loads reliably between dissimilar materials.
Solution Approach 2:
The patent applies local quality by treating only the connection regions of the CFRP shaft tube with surface modification techniques, rather than the entire shaft tube. This localized treatment enhances bonding capability at the joint interfaces where it is most needed, while leaving the rest of the CFRP structure unchanged to maintain its lightweight properties.
3Ease of manufacture
If spline forks are inserted into CFRP shaft tube with glue layer, then connection is achieved, but thermal expansion differences cause joint loosening under temperature variations
Solution Approach 1:
The patent addresses thermal expansion differences by designing the joint structure to accommodate differential expansion between CFRP and metal components. This may include providing clearance gaps, using compliant mounting features, or selecting materials with matched thermal expansion coefficients to prevent joint loosening under temperature cycling conditions.
4Reliability
If Z-pin sleeve is added for connecting CFRP drive shaft with metal flange, then reliable connection is achieved, but structure becomes complex with many manufacturing procedures and high cost
Solution Approach 1:
The patent extracts or removes the complex Z-pin sleeve intermediate connection structure from the design. Instead, it adopts a more direct connection approach between CFRP shaft tube and metal universal joint forks, simplifying the joint structure while maintaining connection reliability through optimized adhesive bonding and surface treatment methods.
Solution Approach 2:
The patent makes the universal joint fork serve multiple functions: it provides the universal joint mechanism, acts as the connection interface to the CFRP shaft tube, and integrates the spline function. This multi-functionality eliminates the need for separate Z-pin sleeves and other intermediate components, reducing structural complexity.
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 provides a lightweight, reliable, and cost-effective CFRP drive shaft with enhanced torsion and bending resistance, reducing vehicle weight, emissions, and improving fuel efficiency, while maintaining structural integrity and durability under varying loads and temperatures.
Implementation Method 1
connected to steel universal joints via a nesting-meshing composite connection using structural adhesive
Data Source
AI summary
The present invention discloses a shaft-tube joint structure of a carbon fiber reinforced plastic (CFRP) drive shaft. The shaft-tube joint structure includes a hollow shaft tube, a plurality of first rectangular teeth being uniformly and circumferentially arranged at both ends of the hollow shaft tube; two shaft-tube joints which are respectively fixed at two ends of the hollow shaft tube, the thickness of the shaft-tube joint being smaller than that of the hollow shaft tube, and an inner wall of the shaft-tube joint being smoothly connected to an inner wall of the hollow shaft tube; and a universal joint, an end thereof being tubular, a plurality of second rectangular teeth being uniformly and circumferentially arranged, the universal joint being matched with and sleeving the outer wall of the shaft-tube joint, and the second rectangular teeth being meshed with the first rectangular teeth.