Metered Liquid Dispensing via Spherical Piston
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Solution Overview
Problem
Existing aerosol dispensing technologies face challenges in delivering metered volumes of liquid without using volatile propellants, which pose environmental and safety risks, and suffer from performance variations due to material inconsistencies and manufacturing costs associated with gas depletion or resilient membrane deterioration.
Innovation Solution
A discharge assembly apparatus with a valve stem and metering chamber that uses a rigid, negatively buoyant liquid discharge element moved by fluid pressure to ensure uniform and precise dispensing of metered volumes, eliminating the need for gas bleeds and minimizing material variability impacts, featuring a spherical piston for reduced friction and improved manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dissolved gas propellant (e.g., butane) is used for aerosol propulsion, then self-propelled liquid delivery is achieved through flash-vaporisation, but environmental harm, fire safety risks, and cost increase due to volatile propellant release occur
Solution Approach 1:
The patent extracts and removes the harmful dissolved gas propellant (butane) from the system, replacing it with an insoluble compressed gas (nitrogen, carbon dioxide or air). This eliminates the flash-vaporisation process and the associated environmental and safety hazards while maintaining the propulsion function through direct gas pressure ejection of the liquid
Solution Approach 2:
The patent changes the physical state and solubility parameters of the propellant gas. Instead of using a dissolved gas that undergoes phase change (flash-vaporisation), the system uses an insoluble compressed gas that remains in the gaseous phase and provides propulsion through pressure differential, fundamentally altering the propellant's interaction with the liquid
2Ease of operation
If compressed gas is bled into the metering chamber to drive liquid ejection, then liquid discharge is achieved, but gas pressure within the aerosol container is depleted requiring high gas to liquid ratio
Solution Approach 1:
The patent segments the gas reservoir function from the liquid container, using a separate insoluble compressed gas source that does not deplete the liquid container's pressure. The gas is introduced through a separate pathway (inlet port) and acts on the liquid from behind, allowing independent control of gas and liquid quantities without requiring high gas to liquid ratios in the same container
Solution Approach 2:
The patent introduces an intermediary mechanism (inlet port and sealing means) that allows compressed gas to be introduced into the metering chamber without depleting the main aerosol container's gas supply. This intermediary pathway enables gas to act as a mediator that drives liquid ejection while preserving the container's overall pressure
3Ease of operation
If elastomeric membrane or resilient bellows is used in the metering chamber to drive liquid discharge, then liquid ejection is achieved through membrane collapse, but performance variations occur due to material inconsistencies and deterioration over lifetime
Solution Approach 1:
The patent extracts and removes the elastomeric membrane or resilient bellows from the metering chamber, replacing the complex resilient wall structure with a simpler rigid chamber design. Liquid ejection is achieved through direct gas pressure acting on the liquid surface, eliminating the intermediary resilient component that causes performance variations and deterioration
Solution Approach 2:
The patent replaces the expensive, performance-critical resilient wall materials with simpler, more durable rigid materials for the metering chamber. This substitution uses materials that do not deteriorate over time, improving long-term reliability and reducing manufacturing complexity
4Manufacturing precision
If rigid, negatively buoyant liquid discharge element is used moved by fluid pressure, then uniform and precise dispensing of metered volumes is achieved, but device complexity increases
Solution Approach 1:
The patent employs a spherical liquid discharge element (spherical piston) within the metering chamber. The spherical geometry provides uniform pressure distribution, reduces friction compared to flat-piston designs, and simplifies manufacturing tolerances while achieving precise metered volume dispensing through the element's displacement by fluid pressure
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 provides a cost-effective, high-yield manufacturing process that maintains aerosol spray performance over the product's lifetime without depleting gas pressure, ensuring consistent and reliable delivery of metered liquid volumes without the use of volatile propellants.
Implementation Method 1
a liquid discharge element which is moveable by fluid pressure from the container from a liquid primed position to a liquid discharged position to effect discharge of said metered volume of liquid
Implementation Method 2
the liquid discharge element is moveable by a returning force from its liquid discharged position to its liquid primed position
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
In the "rest" condition illustrated in Fig. 1, the piston (131) is at its lower limit position and the metering valve assembly (103) is filled with liquid up to the level of seal (129). Once the valve stem (104) is depressed, th apertures (128) move away from the upper seal (129) so as to open to fluid flow, and the lower seal (130) moves down to engage against the inner wall of the lower housing section (107b). Thus liquid flow through apertures (128) occurs. The piston (131) is now forced upwardly by liquid pressure so that it moves from its lower limit position to its upper limit position and, in doing so, causes the metered volume of liquid (134b) to be dispensed. Once the valve stem is released and it returns to its uppermost position under the action of spring (122), the apertures (128) again become closed to liquid flow but liquid is now able to flow past the seal (130) and enter the lower chamber (134a) above the level of the piston (131) which now moves downwardly to its lower limit position so that the metered volume (134b) is recharged.