Flexible Hollow Shaft With Local Core Reinforcement for Torque and Bending
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Solution Overview
Problem
Flexible shafts used in applications like heart catheter pumps face issues with noise development, mechanical knocking, and high wear due to imbalance and mechanical irregularities, especially at high speeds. Additionally, there is a challenge in transferring high torque with minimal mass and small diameter while maintaining tight bending radii.
Innovation Solution
The flexible shaft arrangement incorporates a throughgoing shaft with hollow sections and core reinforcements. The core sections are strategically positioned to provide additional stiffness and stability, while spacers with smaller diameters are used to maintain flexibility in other sections. This design allows for varying stiffness and flexibility along the shaft, optimizing performance for specific applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible shaft is used to transfer torque to difficult-to-access points, then accessibility is improved, but mechanical irregularities and imbalance occur at high speeds
Solution Approach 1:
The flexible shaft is divided into multiple individual wires or strands that are twisted together. Each wire acts as an independent element, and their collective arrangement provides flexibility while maintaining rotational balance. This segmentation allows the shaft to bend and reach difficult locations while reducing mechanical irregularities through the distributed structure.
Solution Approach 2:
The flexible shaft employs a composite structure consisting of multiple materials with different properties. The shaft combines flexible wire elements with balancing weights or counterweights made from dense materials. This composite approach enables the shaft to achieve both flexibility for accessibility and mass distribution for reducing imbalance and vibration at high speeds.
2Weight of moving object
If the shaft diameter is reduced to minimize mass, then torque transfer capability deteriorates
Solution Approach 1:
The shaft uses a composite construction with multiple thin wires twisted together, creating a structure that has both low mass and high torsional strength. The twisted arrangement of numerous fine wires provides sufficient torque transfer capability while keeping the overall diameter and mass minimal, enabling the shaft to meet both weight and power transmission requirements.
Solution Approach 2:
Instead of increasing diameter to improve torque capacity, the invention utilizes the dimensional arrangement of twisted wires in a helical configuration. This transforms the structural approach from radial thickness to longitudinal twisting, allowing torque transfer through the twisted geometry rather than relying on increased cross-sectional area, thus maintaining low mass while achieving adequate power transmission.
3Shape
If the shaft diameter is reduced to achieve tight bending radii, then torque transfer capability deteriorates
Solution Approach 1:
The shaft is constructed from multiple independent wire segments twisted together, allowing each wire to flex independently during bending. This segmented structure enables the shaft to achieve tight bending radii without compromising the overall torque transfer capability, as the individual wires can accommodate curvature while maintaining their load-bearing properties.
Solution Approach 2:
The composite wire structure combines flexibility with strength, allowing the shaft to bend to tight radii while maintaining sufficient torque capacity. The multiple wire elements arranged in a twisted composite structure provide both the flexibility needed for small bending radii and the collective strength required for effective torque transfer.
4Stability of the object's composition
If core sections are added to reinforce the shaft, then stiffness is improved, but flexibility in those sections deteriorates
Solution Approach 1:
The shaft incorporates core reinforcements only in specific sections where additional stiffness is required, rather than making the entire shaft uniformly stiff. These localized core sections provide stability and support where needed, while the remaining portions of the shaft maintain their natural flexibility, allowing the structure to adapt to different operational requirements along its length.
Data Source
AI summary
A flexible shaft arrangement is described herein having a flexible hollow shaft (1, 2) which has an end at the drive side and an end at the output side, wherein the hollow shaft is reinforced sectionally between these ends by a core (3, 4) extending in its interior. Stiffer and more flexible sections can hereby be selectively positioned within the shaft arrangement.