Drive Cable–Hollow Shaft Coupling With Porous Polymer Bonding
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Solution Overview
Problem
Current ventricular assist devices face challenges in securely coupling drive cables to hollow shafts, particularly in maintaining a continuous lumen and ensuring strong bonding between the drive cable and the shaft, which is crucial for mechanical stability and cardiac support functions.
Innovation Solution
A method involving a drive cable with coiled wires is coupled to a hollow shaft using a molten polymer, such as PEEK, where the cable and shaft are placed over a mandrel to maintain a continuous lumen, and the polymer is flowed through coupling-tube pores to bond them together, with optional heat-shrinking and tab insertion for enhanced strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a drive cable and hollow shaft are coupled using traditional bonding methods, then the bonding strength may be sufficient, but the continuous lumen cannot be maintained and mechanical stability is compromised
Solution Approach 1:
The coupling tube is designed with porous walls that allow molten polymer to penetrate through the tube walls and bond the drive cable to the hollow shaft. The pores enable the bonding material to flow through and create strong adhesion while preserving the continuous lumen path for fluid flow.
Solution Approach 2:
The invention uses a composite bonding approach combining molten polymer material with the porous coupling tube structure. The polymer infiltrates the porous walls and bonds the drive cable coiled wires to the hollow shaft, creating a composite joint that maintains both strength and lumen continuity.
2Stability of the object's composition
If the drive cable and shaft are bonded using molten polymer, then the continuous lumen is maintained, but the bonding strength and mechanical stability may be insufficient
Solution Approach 1:
The porous walls of the coupling tube enable molten polymer to penetrate through and create strong bonding between the drive cable and hollow shaft. The polymer fills the porous structure and solidifies to form a mechanically strong connection that maintains lumen continuity.
Solution Approach 2:
The coupling process involves changing the temperature parameter by heating the molten polymer to a temperature where it flows easily through the porous coupling tube walls. Upon cooling, the polymer solidifies and forms a strong bond, utilizing temperature parameter changes to achieve both lumen maintenance and bonding strength.
3Strength
If tabs are inserted into the shaft pores, then the mechanical coupling strength is enhanced, but the device complexity increases
Solution Approach 1:
The coupling tube is designed with discrete tabs that protrude into the shaft pores. These segmented structural features provide enhanced mechanical coupling at specific locations without requiring complete redesign of the entire coupling structure, balancing strength enhancement with manageable 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
This solution provides a strong, reliable bond between the drive cable and shaft, maintaining a continuous lumen and enhancing mechanical stability, thereby supporting cardiac function effectively.
Implementation Method 1
a molten material is flowed between the coiled wires at the drive-cable end via the coupling-tube pores, and into the hollow-shaft end via the coupling-tube pores and shaft pores, such that, upon solidifying, the material bonds the drive cable to the shaft
Implementation Method 2
heat is applied to the sleeve of the material and to the outer sleeve. The applied heat melts the sleeve of the material, thereby forming the molten material, and shrinks the outer sleeve such that the outer sleeve forces the molten material between the coiled wires of the drive cable and into the proximal end of the axial shaft
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Apparatus and methods are described including inserting a drive-cable end of a drive cable (130), which includes a plurality of coiled wires (134), and a hollow-shaft end of a hollow shaft (92, 131), which hollow-shaft end is shaped to define multiple shaft pores (152), into opposing ends of a coupling tube (150), which is shaped to define multiple coupling-tube pores (173). While the drive-cable end and hollow-shaft end are inside the coupling tube (150), a molten material is flowed between the coiled wires (134) at the drive-cable end via the coupling-tube pores (173), and into the hollow-shaft end via the coupling-tube pores (173) and shaft pores (152), such that, upon solidifying, the material bonds the drive cable (130) to the shaft (92, 131). Other applications are also described.