External Drive Unit Purge-Line Cooling for Heart Assist Pumps
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Solution Overview
Problem
Existing heart assist devices face issues with motor overheating due to inadequate heat dissipation, particularly when operated in enclosed environments, posing a health risk to patients and compromising device functionality.
Innovation Solution
An external drive unit for an implantable heart assist pump that utilizes a purge line in thermal contact with the motor housing and catheter to transfer heat to a purge medium, which is then injected into the catheter or fluid gaps, effectively cooling the motor and reducing friction losses, while also allowing heat transfer to patient tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling fins are added to the motor housing to improve heat dissipation, then heat removal capability is improved, but device complexity and ease of cleaning deteriorate
Solution Approach 1:
The patent introduces a heat conductive element as an intermediary between the motor housing and the purge line. This element facilitates thermal energy transfer from the motor housing to the purge medium flowing through the purge line, enabling efficient heat dissipation without modifying the external housing structure with cooling fins. The heat conductive element acts as a thermal bridge that resolves the contradiction by providing internal heat transfer pathway.
Solution Approach 2:
The patent utilizes the purge medium (fluid) flowing through the purge line as a cooling mechanism. By introducing thermal contact between the purge line and the motor housing (via the heat conductive element), the flowing fluid continuously absorbs and carries away heat from the motor housing. This hydraulic cooling approach replaces the need for static cooling fins and achieves dynamic heat dissipation without increasing structural complexity.
2Object-affected harmful factors
If the motor is operated in enclosed environments (under duvet or surgical drapery), then patient comfort is improved, but heat dissipation capability deteriorates
Solution Approach 1:
The heat conductive element serves as a mediator that enables heat transfer from the motor housing to the purge medium even when the device is enclosed. The purge line provides a dedicated thermal pathway that bypasses the need for external air convection, allowing the motor to be cooled effectively regardless of whether the device is covered by duvet or surgical drapery. This resolves the contradiction between patient comfort and heat dissipation.
3Temperature
If purge line is in thermal contact with motor housing to cool the motor, then heat management is improved, but additional components and complexity are added
Solution Approach 1:
The heat conductive element is a compact intermediary component that enables thermal coupling between the motor housing and the purge line without requiring complex modifications. This single element provides an efficient thermal pathway while minimizing the increase in device complexity. The element can be integrated into the existing motor housing structure, adding minimal bulk or 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
The solution provides efficient heat management, reducing the risk of motor overheating, simplifying electronic control, and ensuring safe operation by maintaining a consistent motor current, even in enclosed conditions, without the need for additional cooling components.
Implementation Method 1
The purge line is in thermal contact with an outer surface of the motor housing and/or with an outer surface of a proximal section of the catheter such that heat is transferred from the outer surface of the catheter in the proximal section and/or from the outer surface of the motor housing to the purge medium
Data Source
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AI summary
The application relates to an external drive unit (7) for an implantable heart assist pump (4). The proposed drive unit (7) comprises a motor housing (51), a transcutaneous drive shaft (3) and a motor (35) for driving the heart assist pump (4). The motor (35) is connectable to the heart assist pump (4) via the drive shaft (3), and the motor (35) is arranged inside the motor housing (51). The drive unit (7) further comprises a catheter (2) surrounding the drive shaft (3) and a purge line (53) for injecting a purge medium into a lumen of the catheter (2) or into a space (41) between the catheter (2) and the drive shaft (3). The purge line (53) is in thermal contact (54, 55) with an outer surface of the motor housing (51) and/or with an outer surface of a proximal section (52) of the catheter (2). Due to the thermal contact (54, 55) heat may be transferred from the outer surface of the catheter (2) in the proximal section (52) and/or from the outer surface of the motor housing (51) to the purge medium.