Tabbed Coupling Tube for Drive Cable to Hollow Shaft Bonding
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Solution Overview
Problem
Current ventricular assist devices face challenges in securely coupling drive cables to hollow shafts, which affects the mechanical stability and efficiency of cardiac support systems, particularly in environments where cardiac output needs to be augmented.
Innovation Solution
A method involving a drive cable with coiled wires coupled to a hollow shaft using a molten polymer, such as PEEK, where the polymer is flowed through coupling tube pores to bond the drive cable to the shaft, with additional reinforcement from tabs and a heat-shrinking process to ensure a strong and continuous lumen connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a molten polymer bonding process is used to couple the drive cable to the hollow shaft, then the strength of the coupling is improved, but the device complexity increases due to the additional bonding process and components
Solution Approach 1:
The coupling tube is pre-loaded with molten polymer material before the drive cable and hollow shaft are inserted. This preliminary preparation of the bonding agent allows for automated assembly without requiring complex post-assembly bonding equipment, thereby improving coupling strength while limiting the increase in device complexity
Solution Approach 2:
The coupling tube acts as an intermediary component that houses both the drive cable and hollow shaft, and also contains the molten polymer bonding material. This single component performs multiple functions: mechanical support, material containment, and bonding facilitation, thereby improving coupling strength while minimizing the addition of separate components
2Reliability
If tabs are pushed into the shaft pores to strengthen the coupling, then the reliability of the connection is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The coupling mechanism is segmented into multiple functional elements: the coupling tube structure, the tabs as discrete engagement features, and the shaft pores as reception features. This segmentation allows each element to be optimized independently - tabs can be designed with specific geometries for reliable engagement while shaft pores can be manufactured with standard tolerances, thereby improving connection reliability without excessively increasing manufacturing precision requirements
Solution Approach 2:
The tabs provide localized reinforcement at specific engagement points within the coupling tube, rather than requiring uniform high-strength construction throughout the entire assembly. This localized approach to strengthening improves connection reliability at critical interfaces while allowing other areas to be manufactured with standard precision, thereby limiting the overall increase in manufacturing precision requirements
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 robust and reliable coupling that maintains a continuous lumen, enhancing the mechanical stability and efficiency of ventricular assist devices, 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
upon solidifying, the material bonds the drive cable to the shaft
Implementation Method 3
an outer sleeve (made of polytetrafluoroethylene, for example) is placed around the sleeve of the material. Next, 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
AI summary
Apparatus and methods are described including inserting a drive-cable end of a drive cable, which includes a plurality of coiled wires, and a hollow-shaft end of a hollow shaft, which hollow-shaft end is shaped to define multiple shaft pores, into opposing ends of a coupling tube having a wall shaped to define multiple tabs. The drive cable is coupled to the shaft by pushing at least some of the tabs into the shaft pores, respectively. Other applications are also described.