Piezoelectric Diaphragm Pump with Variable Contact Area
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Solution Overview
Problem
Existing liquid feed pumps for high-performance liquid chromatography face challenges in achieving both high-pressure, small flow rates and low-pressure, large flow rates while minimizing particle generation and maximizing design flexibility.
Innovation Solution
A flow control device with a diaphragm pump that includes a piezoelectric actuator, a reciprocating member, and a seal portion, where the diaphragm receiving surface's contact area varies with internal pressure, allowing for adjustable stroke and reduced load on the reciprocating member, enabling precise control of flow rates and preventing excessive deformation wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric actuator is used to drive the diaphragm, then particle generation is eliminated and pump life is extended, but the stroke (displacement) design flexibility is limited
Solution Approach 1:
The patent introduces a reciprocating member that can dynamically adjust the stroke of the piezoelectric actuator. The reciprocating member translates the limited displacement of the piezoelectric actuator into a variable stroke through mechanical amplification, allowing the pump to adapt to different flow rate requirements while maintaining the particle-free advantage of piezoelectric drive.
Solution Approach 2:
The reciprocating member acts as an intermediary between the piezoelectric actuator and the diaphragm. It receives the limited motion from the piezoelectric actuator and transforms it into a larger, variable stroke that can deform the diaphragm effectively, thus bridging the gap between the actuator's limited displacement and the required pump stroke.
2Power
If the plunger method is used to achieve high pressure discharge, then high pressure and flow rate can be secured, but particle generation occurs and pump life is reduced
Solution Approach 1:
The patent replaces the traditional plunger mechanical system with a piezoelectric actuator-driven diaphragm system. The piezoelectric actuator eliminates sliding contacts and mechanical wear associated with plungers, thereby preventing particle generation and extending pump life, while still achieving high pressure discharge through the deformable diaphragm.
3Strength
If the diaphragm contact area with the recessed portion surface is large, then the diaphragm is well supported, but the stroke is limited and flow rate control flexibility is reduced
Solution Approach 1:
The patent makes the diaphragm support condition dynamic by allowing the diaphragm to selectively contact or separate from the recessed portion surface based on operating conditions. During high-pressure operation, the diaphragm contacts the surface for support; during low-pressure operation, it separates to increase stroke, thus providing flow rate control flexibility while maintaining structural support when needed.
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 device achieves a wide dynamic range of flow rates, reduces particle generation, and extends the pump's lifespan by automatically adjusting the diaphragm's deformation range based on pressure, ensuring efficient operation at both high and low pressures.
Implementation Method 1
the driving member includes a piezoelectric actuator configured to drive the diaphragm
Implementation Method 2
the diaphragm deforms when pressed by the reciprocating member
Data Source
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AI summary
The present invention provides a liquid feed pump in which substantially no particles are generated. The liquid feed pump includes: a pump housing; a diaphragm 180 that forms a pump chamber 123 together with a recessed portion surface and partitions the pump chamber 123 from a hole; a reciprocating member that is inserted into the hole to be capable of reciprocation, and reciprocates so as to deform the diaphragm 180; a driving member 140 that displaces the reciprocating member in a reciprocation direction; a seal portion that sandwiches the diaphragm 180 so as to seal the diaphragm 180 in a position surrounded by an outer peripheral side of the recessed portion surface; and a diaphragm receiving surface that is provided between the seal portion and an opening portion such that a contact area thereof, which is a surface area of a surface that contacts the diaphragm 180, varies in accordance with the displacement and an internal pressure of the pump chamber 123. The contact area decreases in response to an increase in the displacement of the reciprocating member to the recessed portion surface side and increases in response to an increase in the internal pressure of the pump chamber 123.