Telescopic Shaft Tension Element Axial Slot Engagement
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Solution Overview
Problem
Existing telescopic shafts face issues with robustness under loads due to the lack of durability in the coupling mechanism between profile tubes, particularly when the inner profile tube is pulled out relative to the middle and outer profile tubes, leading to a loss of torque transmission capability.
Innovation Solution
A telescopic shaft design featuring an inner, middle, and outer profile tube arrangement with a tension element having axial slots in the middle profile tube, where engagement means connect the inner profile tube to the tension element, limiting displacement and providing a robust connection, using standard parts and ensuring resilience without significant weakening of the tension element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pull wire is used to couple the inner profile tube to the middle profile tube, then the inner profile tube can be pulled out to a certain extent before the pull wire is pulled taut, but the pull wire lacks robustness and can no longer withstand the loads that occur after a certain period of use
Solution Approach 1:
The coupling function is segmented between the tension element (providing elastic coupling) and the engagement means with axial slots (providing mechanical engagement). This segmentation allows the system to combine the benefits of displacement capability and load robustness by distributing functions across different components.
Solution Approach 2:
The tension element acts as a pre-designed cushioning element that absorbs initial loads and allows controlled displacement before becoming taut. This beforehand cushioning protects the engagement means from excessive loads during the displacement phase, ensuring robustness while maintaining ease of operation.
2Strength
If the tension element is made with a full cross-section for strength, then it can withstand tensile loads, but it increases weight and complicates manufacturing
Solution Approach 1:
The tension element has varying cross-sectional properties: full cross-section at the ends for maximum strength where loads are applied, and reduced cross-section in the middle portion where weight reduction is beneficial. This local quality optimization maintains necessary strength while reducing overall weight and simplifying manufacturing.
3Power
If the engagement means are rigidly connected to the inner profile tube, then torque transmission is efficient, but the coupling cannot accommodate displacement between the inner and middle profile tubes
Solution Approach 1:
The coupling system transitions from a static rigid connection to a dynamic system where the engagement means can move relative to the inner profile tube through the axial slots in the tension element. This dynamic capability allows the system to accommodate displacement while maintaining torque transmission through the engaged profile tubes.
Data Source
AI summary
The telescopic shaft (1) has an inner section tube (2), a mid-section tube (3) and an outer profiled tube (4) which are arranged relative to one another. The length of inner section, mid-section and outer profiled tubes is changed slidably. A tension element (5) with axial slot (6) is axially immovably held with respect to the mid-section tube. An engagement unit (7) is connected to the inner section tube, for engaging the axial slot of the tension element to the boundary of a displacement path between the inner section tube and the tension element. An independent claim is included for drive shaft.