Composite Driveshaft Crash-Collapse Joint for Controlled Telescoping
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Solution Overview
Problem
Composite driveshafts face challenges when adapted for vehicle use due to higher temperatures, rotational speed variations, and stricter size constraints, leading to potential collateral damage during crashes due to compressive forces.
Innovation Solution
A composite vehicle driveshaft with a crash collapse system that allows controlled longitudinal collapse through a telescopic mechanism, featuring a stub end assembly and sleeve with splined engagement, interference fit, and adhesive bonding to manage compressive forces during crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If composite driveshaft strength is increased to address higher temperatures and rotational speed variations, then reliability is improved, but collateral damage during crash increases due to substantial columnar strength
Solution Approach 1:
The driveshaft is divided into multiple segments including a telescoping mechanism with a first section and a second section that can move relative to each other. This segmentation allows the driveshaft to maintain high strength in normal operation while enabling controlled collapse during crash events to reduce collateral damage.
Solution Approach 2:
The telescoping mechanism provides dynamic adaptability, allowing the driveshaft to transition from a rigid high-strength state during normal operation to a collapsible state during crash. The mechanism includes a telescoping assembly with movable sections that can change the overall length and energy absorption characteristics of the driveshaft based on operational conditions.
2Reliability
If composite driveshaft strength is increased to address shock-loads and extreme torque spikes, then reliability is improved, but device complexity increases due to need for crash collapse system
Solution Approach 1:
The crash collapse functionality is merged with the normal torque transmission function through an integrated telescoping mechanism. The same structural components that provide strength for torque transmission also enable controlled collapse during crash, eliminating the need for separate crash management systems and reducing overall device complexity.
Solution Approach 2:
The telescoping mechanism serves multiple functions: it maintains high strength for torque transmission during normal operation, enables controlled collapse during crash to reduce collateral damage, and provides adaptability for different operational conditions. This multi-functionality reduces the need for additional specialized components.
3Ease of operation
If composite driveshaft is designed with stricter diameter constraints, then ease of operation is improved, but manufacturing precision becomes more difficult
Solution Approach 1:
The telescoping mechanism employs a nested structure where one section is inserted within another, allowing the driveshaft to achieve a compact form factor when collapsed while maintaining full length when extended. This nesting approach enables compliance with strict diameter constraints while preserving the necessary functional length for torque transmission.
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 enables controlled telescopic movement of components, reducing the risk of collateral damage by allowing the driveshaft to collapse under sufficient compressive forces, maintaining torque capacity and preventing backlash, thus enhancing safety and performance.
Implementation Method 1
The sleeve may define a sleeve inner circumferential surface with splines that define a sleeve splined segment. The stub shaft may include a stub shaft base with an outer circumferential surface that has splines that define a stub shaft base splined segment. The splines of the sleeve and stub shaft may, for example, straight or helical and correspond to each other to allow their splined engagement.
Implementation Method 2
The engaged sleeve and stub shaft base segments may provide an interference fit between each other at the collapsible joint to longitudinally or axially fix the stub shaft with respect to the composite tube when in the extended state. The interference fit between the stub shaft base and the sleeve may be formed by a press-fit and/or a thermal shrink-fit procedure.
Implementation Method 3
The sleeve may be arranged concentrically within and be bonded to the sleeve-end of the composite tube, such as by way of an adhesive.
Data Source
AI summary
A composite vehicle driveshaft is provided with a crash collapse system that allows for a controlled longitudinal collapse of the driveshaft by facilitating telescopic movement of various components with respect to each other during a crash event. The crash collapse system may include a collapsible joint with a sleeve that is concentrically bonded in an end of a composite tube and a stub end assembly that is spline-engaged and interference fit within the sleeve, such as by way of a press-fit and/or a thermal shrink-fit procedure. This relationship may rotationally lock and axially fix the stub end assembly to the sleeve unless, during a crash event, the composite vehicle driveshaft experiences a compression or push-type force that exceeds a minimum breakaway or collapse force value that longitudinally and telescopically collapses the composite vehicle driveshaft.