Metered Dose Valve Stem Assembly for Propellant-Free Liquid Discharge
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Solution Overview
Problem
Existing aerosol dispensing technologies face challenges such as the use of environmentally harmful propellants like butane, high manufacturing costs due to gas depletion, performance variations from resilient walls, and manufacturing complexities in metered dose delivery.
Innovation Solution
A discharge assembly with a housing, valve stem, and chamber configuration that includes a fin and seat for a temporary interference seal, a chamfered or curved sealing surface, and a liquid discharge element, allowing for a more reliable, efficient, and cost-effective metered liquid discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dissolved gas propellant (e.g., butane) is used for metered aerosol delivery, then self-propelled liquid discharge is achieved, but environmental harm, fire safety risk, and cost increase
Solution Approach 1:
The patent changes the physical state of the propellant from dissolved gas (butane) to compressed insoluble gas (nitrogen, carbon dioxide, or air). This parameter change eliminates the environmental and safety issues associated with volatile organic compounds while maintaining the propellant's ability to deliver metered doses through pressure-driven ejection
Solution Approach 2:
The patent converts the previously harmful dissolved gas propellant system into a beneficial compressed gas system. By using insoluble compressed gases that are environmentally friendly and non-flammable, the invention transforms a harmful propulsion method into a safe and sustainable one, while still achieving effective metered dose delivery
2Ease of operation
If compressed gas is bled into the metering chamber to drive liquid ejection, then liquid discharge is achieved, but gas pressure depletion requires high gas to liquid ratio increasing manufacturing costs
Solution Approach 1:
The patent extracts the gas bleeding function from the metering chamber system. By providing a separate gas supply source connected to the ejection orifice, the invention eliminates the need to deplete gas from the aerosol container, thereby reducing the gas to liquid ratio and associated manufacturing costs while maintaining effective liquid ejection
3Ease of operation
If elastomeric membrane or resilient bellows is used in the metering chamber to drive liquid discharge, then liquid ejection is achieved, but performance variations occur due to material variations and deterioration
Solution Approach 1:
The patent replaces the resilient mechanical system (elastomeric membrane or bellows) with a rigid mechanical system consisting of a valve stem, valve body, and fin mechanism. This substitution eliminates performance variations caused by material deterioration and ensures consistent metered dose delivery throughout the product lifetime
Solution Approach 2:
Instead of using a resilient wall that expands and contracts to drive discharge, the patent inverts the approach by using a rigid valve stem that moves axially to control fluid flow paths. The fin on the valve stem creates seals through relative movement, achieving liquid discharge without relying on resilient material properties
4Reliability
If complex valve structures are used to achieve reliable sealing and metered discharge, then discharge reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent segments the valve structure into distinct functional components: a valve stem with an integrated fin, a valve body with sealed chambers, and a dip tube. This segmentation allows each component to be optimized for its specific function while simplifying the overall manufacturing process through modular assembly
Solution Approach 2:
The patent merges the sealing fin directly onto the valve stem as an integral feature, eliminating the need for separate sealing components. This merging simplifies the valve structure by reducing the number of parts while maintaining reliable sealing through the fin's interference fit with the valve body
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 assembly provides a more reliable seal, reduced manufacturing complexity, lower failure rates, and consistent metered doses without the need for volatile propellants, while maintaining performance throughout the product's lifetime.
Implementation Method 1
a fin creates a temporary interference seal between the interior of the housing and the exterior of the valve stem so as to close said second fluid transfer passageway to fluid flow
Implementation Method 2
a liquid discharge element moveable along said chamber from a liquid primed position to a liquid discharged position to effect discharge of the metered volume of liquid
Implementation Method 3
said valve stem being axially moveable relative to the housing between a first limit position at which the assembly is closed to liquid discharge and a second limit position for discharge of the metered volume
Data Source
AI summary
A discharge assembly for discharging a metered volume of a liquid held in a pressurised or pressurisable container with a housing having a liquid inlet at a first end thereof, a valve stem having a body locating within said housing and having a head portion projecting from the second end of said housing, said valve stem being axially moveable relative to the housing between a first limit position closed to liquid discharge, and a second limit position for discharge of the metered volume, a chamber provided within the body of the valve stem and having a liquid inlet towards a first end of the chamber and a first fluid transfer passageway providing communication between the chamber and the exterior of the valve stem, and a liquid discharge element moveable from a liquid primed position to a liquid discharged position to effect discharge of the metered volume of liquid.