Axially Movable Rotor Assembly for Blood Pump Pressure Balancing
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Solution Overview
Problem
Current blood pumping devices for congestive heart failure patients lack effective balancing mechanisms for left and right circulations, leading to potential accumulation of blood in organs and increased risk of heart failure or liver failure due to unbalanced arterial blood flows and atrial pressures.
Innovation Solution
A valveless, sensorless, pulsatile, continuous flow total artificial heart with a two-stage rotodynamic pump configuration that self-balances left and right circulations by adjusting the axial position of a rotor assembly within a brushless DC motor winding, using hydraulic pressures to modulate the performance of the pump stages and balance inlet pressures without electronic intervention, or with external electronic control via a solenoid-type element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single blood pumping device is used for both left and right circulations, then device complexity is reduced, but inlet pressure balancing between the two circulations becomes difficult to achieve
Solution Approach 1:
The rotor assembly is designed to be movable axially relative to the stator, allowing dynamic adjustment of the clearance between rotor and stator. This dynamic adjustment enables the pump to automatically balance inlet pressures between left and right circulations by changing the hydraulic performance characteristics in response to pressure differentials, resolving the contradiction between simplified structure and reliable pressure balancing.
2Measurement precision
If electronic control systems are used to balance left and right circulations, then pressure balancing precision is improved, but device complexity and reliability are worsened
Solution Approach 1:
The pump employs a self-regulating mechanism where the movable rotor assembly automatically adjusts its position in response to inlet pressure differentials between left and right circulations. This self-service approach eliminates the need for external electronic sensors and control systems, achieving reliable pressure balancing while minimizing device complexity and improving reliability through reduced electronic components.
3Manufacturing precision
If the rotor assembly is fixed in position, then manufacturing precision is improved, but hydraulic performance adaptability is reduced
Solution Approach 1:
The rotor assembly is designed with movable capability along the axial direction, allowing it to adapt its position based on operating conditions and pressure differentials. This dynamic design enables the pump to adjust hydraulic performance characteristics to match varying physiological demands, resolving the contradiction between manufacturing precision and hydraulic adaptability by allowing controlled movement within precision-engineered tolerances.
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 effectively balances systemic and pulmonary blood flows and atrial pressures, ensuring stable hemodynamics and preventing blood accumulation in organs, thereby improving patient outcomes by adjusting the geometry of the pump stages in response to pressure differentials, allowing for continuous operation and reducing the need for active control systems.
Implementation Method 1
The rotor assembly is free to move axially in response to the hydraulic environment, thereby changing clearances in the two opposed rotodynamic pumping stages, affecting relative performance to balance the inlet pressures
Implementation Method 2
a single moving part, which revolves within a brushless, sensorless DC motor winding
Data Source
AI summary
A pump (10) includes a housing, a stator (20) supported in the housing, and a rotor assembly (30). The rotor assembly (30) includes a rotor (32) supported in the housing for rotation relative to the stator (20) about an axis (12). The rotor assembly (30) also includes a first impeller (34) operatively coupled to a first axial end of the rotor (32) for rotation with the rotor about the axis (12). The rotor assembly further includes a second impeller (36) operatively coupled to a second axial end of the rotor (32), opposite the first axial end, for rotation with the rotor about the axis (12). The rotor assembly (30) is movable along the axis (12) relative to the housing to adjust hydraulic performance characteristics of the pump (10).