Disc Pump Cavity Resonant Frequency Regulation
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Solution Overview
Problem
Disc pumps with disc-shaped cavities face challenges in achieving high amplitude pressure oscillations and efficient fluid pumping due to dampening effects at the interface between the driven end wall and sidewall, and conventional valves are limited by lower operating frequencies, making them unsuitable for high-frequency applications required in portable devices.
Innovation Solution
A disc pump system with a cylindrical cavity having a variable resonant frequency, utilizing an internal sidewall with a circular coil that expands or contracts with temperature changes to maintain resonant frequency matching, and high-frequency valves with offset apertures and a flexible isolator to reduce dampening, enabling efficient high-frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the driven end wall interface with the sidewall is structured to reduce dampening, then the amplitude of pressure oscillations is improved, but the device complexity increases due to the isolator structure
Solution Approach 1:
An isolator is introduced as an intermediary component between the driven end wall and the sidewall. This isolator reduces the dampening effect at the interface, allowing larger amplitude pressure oscillations to be achieved without excessive energy loss at the boundary interface.
Solution Approach 2:
The driven end wall is segmented into a central portion and a peripheral portion, with the isolator positioned at the peripheral portion. This segmentation allows the interface region to be treated separately from the main pumping cavity, enabling optimization of the interface for reduced dampening while maintaining the overall pumping function.
2Device complexity
If conventional valves are used for fluid control, then the device complexity is reduced, but the operating frequency is limited to below 500 Hz
Solution Approach 1:
The valve design incorporates a flexible membrane that can dynamically respond to high-frequency pressure oscillations. This flexible structure allows the valve to operate at frequencies above 500 Hz, overcoming the limitation of conventional rigid valve designs while maintaining a relatively simple overall structure.
Solution Approach 2:
A flexible membrane is used as the valve element instead of conventional rigid components. This flexible film can rapidly respond to pressure changes at high frequencies, enabling operation above 500 Hz while keeping the valve structure compact and simple.
3Productivity
If the resonant frequency of the cavity is matched to the actuator frequency, then the efficiency is improved, but the resonant frequency drifts with temperature changes
Solution Approach 1:
The cavity is designed to utilize thermal expansion effects, where the physical dimensions of the cavity change with temperature. This natural thermal expansion compensates for the frequency drift, maintaining resonant frequency matching between the cavity and actuator across varying temperature conditions without requiring active control.
Solution Approach 2:
The resonant frequency of the cavity is made variable through design features that allow it to change with temperature. This parameter change in the cavity's resonant frequency enables it to track and maintain matching with the actuator's resonant frequency despite temperature variations, preserving pumping efficiency.
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 system achieves efficient high-frequency fluid pumping with reduced dampening and increased amplitude of pressure oscillations, ensuring disc pump efficiency and inaudible operation, suitable for portable devices requiring high-frequency fluid management.
Implementation Method 1
an internal sidewall disposed within a cylindrical sidewall for compensating for changes in the resonant frequency of a disc pump cavity resulting from changes in temperature. The internal sidewall includes a circular coil configured to expand in response to an increase in temperature and contract in response to a decrease in temperature.
Implementation Method 2
The actuator causes an oscillatory motion of the driven end wall in a direction substantially perpendicular thereto, thereby generating displacement oscillations of the driven end wall. The displacement oscillations generate corresponding pressure oscillations of fluid within the cavity.
Implementation Method 3
an isolator operatively associated with the peripheral portion of the driven end wall to reduce dampening of the displacement oscillations
Data Source
Figure 1A
Figure 1B~1C
Figure 1D~1F
AI summary
A disc pump system includes a pump body having a substantially cylindrical shape defining a cavity for containing a fluid. The cavity having a resonant cavity frequency is formed by an internal sidewall and substantially closed at both ends by a first end wall and a driven end wall. The disc pump system includes an actuator that is driven a frequency (J) that corresponds to the fundamental resonant frequency of the actuator. The internal sidewall is configured to expand and contract in response to changes in temperature, thereby causing the actuator and cavity to have approximately the same resonant frequencies over a range of operating temperatures.