Fuel Nozzle Spout Dripless Design Using Hydraulic Fins and Vent Restrictor
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Solution Overview
Problem
Existing fuel dispensing nozzles struggle to prevent fuel drops from exiting after shut-off, leading to environmental pollution and non-compliance with regulations, as prior solutions like valves tend to corrode and malfunction, allowing more than three drops to escape during the post-fueling drip test.
Innovation Solution
The implementation of a spout with hydraulic damming fins, a bushing with arc weirs, and a vent tube restrictor to retain residual fuel and prevent drop formation, ensuring fewer than three drops exit the nozzle within ten seconds, meeting regulatory standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a valve is added to block fuel drops at the spout end, then the number of drops is reduced, but the device weight and cost increase, and the valve corrodes and malfunctions after substantial usage
Solution Approach 1:
The invention removes the valve component entirely from the spout assembly. Instead of using a valve to block fuel drops, the design relies on the natural capillary action and surface tension of the fuel within the spout's internal geometry to prevent dripping, thereby eliminating corrosion and malfunction issues associated with valves
Solution Approach 2:
The spout design allows the fuel itself to prevent dripping through capillary action and surface tension forces. The fuel's own physical properties are harnessed to control its flow and prevent drops, eliminating the need for external mechanical components like valves
2Object-generated harmful factors
If a valve is added to block fuel drops, then dropping is stopped initially, but the device complexity and cost increase
Solution Approach 1:
The invention extracts the valve component from the nozzle assembly entirely. The spout is designed with internal geometry that utilizes capillary action and surface tension to prevent fuel drops without requiring any additional blocking mechanisms, thereby simplifying the overall device structure
Solution Approach 2:
The invention changes the physical parameters of the spout interior surface, such as surface energy and wettability, to enhance capillary action. By modifying these surface properties rather than adding mechanical components, the design achieves drop prevention with simpler structure
3Quantity of substance
If capillary and wetting action are used to retain fuel on the interior surface of the spout, then fuel is held in the spout, but the risk of fuel drops escaping increases
Solution Approach 1:
The invention applies different surface properties to different regions of the spout interior. The surface is designed with specific local characteristics that promote fuel retention through capillary action in certain areas while preventing drop formation and escape in other areas, creating a gradient of surface energy distribution
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 combination of hydraulic damming fins, arc weirs in the bushing, and a vent tube restrictor effectively retains fuel within the nozzle, reducing post-shutoff drips to less than three, adhering to environmental regulations and minimizing fuel evaporation.
Implementation Method 1
The fuel encounters a valve that closes automatically upon release of the lever. Fuel becomes drops beyond the valve. As the valve wears, more fuel escapes and generates drops.
Implementation Method 2
Capillary and wetting action retains fluids on the interior surface of the spout, raising the risk of fuel drops later escaping from the spout.
Implementation Method 3
the sudden shutoff of the nozzle causes a negative vacuum in the spout causing fuel to rebound inside the spout due to the inertia of the fuel flow
Data Source
AI summary
A dripless means for a fuel dispensing nozzle begins with a nozzle for dispensing fuel into automobile tanks. Regulations limit drainage of the spout to within ten seconds, met by the present invention that prevents fuel drops from exiting the spout. First, the spout retains fuel drops behind a dam made of a series of fins upon the interior of the spout. Second, the present invention has a bushing with a weir that works in combination with the damming. Third, the nozzle has a vent tube within the spout where a plug constricts its diameter to limit the fuel drawn into the vent tube. With proper use, the present invention retains fuel drops in the spout to meet the regulations.