Two-Way Diaphragm Accumulator for Implantable Pump Volume
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Solution Overview
Problem
Existing implantable valve pump designs face challenges in energy efficiency and performance due to the limitations of one-way diaphragm accumulators, which require larger sizes to increase volume, leading to performance degradation, increased pressure, and manufacturing complexities, while also restricting drug delivery pulse size.
Innovation Solution
A two-way diaphragm accumulator design that deflects in both directions, allowing for increased volume pumping without size and weight increases, using a pressurized gas chamber to bias the diaphragm and optimize energy utilization, combined with a spacer plate featuring a concave surface and annular groove for efficient fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the accumulator size is increased to increase the volume pumped, then the volume delivered per cycle is improved, but the device size and weight increase
Solution Approach 1:
The diaphragm performs periodic bidirectional deflection cycles, moving in a first direction during the filling stroke to receive fluid and in a second direction during the delivery stroke to deliver fluid. This periodic bidirectional action allows the same diaphragm surface area to process twice the volume compared to unidirectional systems, effectively doubling the quantity of substance pumped without increasing device size or weight.
2Quantity of substance
If the accumulator size is increased to increase the volume pumped, then the volume delivered per cycle is improved, but the device complexity increases
Solution Approach 1:
The diaphragm serves multiple functions: it acts as a barrier between the fluid chamber and gas chamber, a flexible wall that deflects to receive and deliver fluid, and a volume displacement mechanism. The gas chamber serves dual purposes as both a pressure source and a mechanism to return the diaphragm to its initial position. This multi-functionality allows the system to achieve doubled pumping volume without adding complex additional components.
Solution Approach 2:
The system uses a gas chamber containing pressurized gas to bias the diaphragm in the delivery direction. The elastic recovery force of the compressed gas automatically returns the diaphragm to its initial position after fluid delivery, eliminating the need for complex mechanical return mechanisms. This pneumatic mechanism simplifies the overall device structure while enabling bidirectional operation.
3Quantity of substance
If the diaphragm deflection distance is increased to increase volume, then the volume delivered is improved, but the diaphragm spring force increases
Solution Approach 1:
Instead of increasing deflection distance, the system uses periodic bidirectional deflection with the same amplitude. The diaphragm deflects in a first direction during filling and in a second direction during delivery, effectively utilizing the same deflection range twice per cycle. This approach doubles the volume delivered without increasing the peak spring force, as the maximum deflection distance remains unchanged.
Solution Approach 2:
The system changes the operational parameter from unidirectional deflection to bidirectional deflection. By reversing the deflection direction periodically using gas pressure bias, the system achieves doubled volume delivery with the same maximum deflection distance and corresponding spring force requirements.
4Quantity of substance
If the intermediate accumulator and reservoir pressures are increased to accommodate larger deflection, then the volume pumped is improved, but the pressure requirements increase
Solution Approach 1:
The bidirectional periodic deflection allows the diaphragm to deliver fluid during the power stroke and receive fluid during the return stroke. This eliminates the need for high pressure during the entire cycle, as pressure is only required during the delivery phase. The gas chamber provides the necessary pressure bias only when needed, reducing overall pressure requirements compared to systems requiring continuous high pressure for larger volume delivery.
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 two-way diaphragm design doubles the volume delivered per cycle while maintaining energy efficiency, reducing the need for larger components and minimizing dead volume, thus enhancing the implant's performance and longevity without increasing size or weight.
Implementation Method 1
a gas chamber containing a pressurized gas, wherein said diaphragm provides a barrier between said pressurized gas and any infusate in said accumulator, and said pressurized gas biases said diaphragm in said second direction
Implementation Method 2
A pressure which is intermediate between the reservoir and the outlet is maintained behind the accumulator so that it fills and empties completely and rapidly
Data Source
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AI summary
An improved implantable valve accumulator pump for the delivery of medication is disclosed. The implantable pump comprises a pressurized drug reservoir. The medication metering assembly comprises a fixed volume accumulator positioned between a pair of valves. The valves alternately open and close to admit medication from the reservoir into the accumulator and to dispense a precise volume pulse to an outlet catheter. In order to improve the pump' s accuracy and to increase pumping volume while optimizing the pump's overall size and energy usage a two way diaphragm accumulator is used. The unit can be externally programmed or can be used in a fixed rate configuration that is never programmed but set at the factory or in the current programmable configuration.