External Drive Unit Purge Line Thermal Contact Cooling
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Solution Overview
Problem
Existing heart assist devices face issues with heat management, particularly when the external motor is positioned close to the patient's body, leading to overheating and potential health risks due to inadequate heat dissipation, especially in enclosed environments.
Innovation Solution
An external drive unit for an implantable heart assist pump that incorporates a purge line in thermal contact with the motor housing and proximal catheter section to efficiently transfer heat away from the motor, using a purge medium like glucose or saline solution to cool the motor and reduce friction losses, thereby preventing overheating and ensuring safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the motor is positioned close to the patient's body for compact device design, then the device size is reduced, but heat dissipation becomes insufficient leading to overheating
Solution Approach 1:
A purge medium (fluid) is introduced as an intermediary substance between the motor and the external environment. The fluid flows through channels in the drive shaft, absorbing heat from the motor and transporting it away from the implant site, enabling effective cooling without increasing device volume
Solution Approach 2:
The invention employs a hydraulic cooling system where a purge fluid is circulated through the drive shaft to remove heat. The fluid flow mechanism allows efficient thermal management in a compact configuration by utilizing fluid dynamics principles for heat transport
2Temperature
If cooling fins are added to the motor housing for heat dissipation, then heat removal is improved, but the device becomes difficult to clean and more complex
Solution Approach 1:
The cooling function is extracted from the motor housing structure itself. Instead of adding external cooling fins to the housing, the cooling mechanism is separated into an independent fluid circulation system within the drive shaft, maintaining a simple smooth housing surface that is easy to clean while achieving effective heat dissipation
Solution Approach 2:
The purge fluid acts as an intermediary heat transfer medium, eliminating the need for direct thermal coupling between the motor housing and external cooling surfaces. This allows the housing to maintain a simple, smooth design while the fluid carries heat away from the motor internally
3Ease of operation
If the motor is operated in an enclosed environment (under duvet or surgical drapery), then patient comfort or surgical sterility is improved, but heat dissipation is insufficient causing overheating
Solution Approach 1:
The purge fluid serves as a portable cooling intermediary that operates independently of the external environment. The closed-loop fluid circulation system within the drive shaft allows the motor to be effectively cooled even when covered by duvets or surgical drapery, as the cooling function is self-contained and does not rely on ambient air flow
Solution Approach 2:
The cooling system operates continuously through constant fluid circulation, ensuring uninterrupted heat removal regardless of external conditions. The purge fluid continuously absorbs and transports heat from the motor, maintaining stable thermal management whether the device is exposed or enclosed
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 proposed drive unit effectively manages heat dissipation without additional components, improving the safety and efficiency of the heart assist device by maintaining a stable motor operation and reducing the risk of tissue damage, even in conditions where ambient air cooling is insufficient.
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. Due to the thermal contact heat may be 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.