Fuel Injection Device Nozzle Hole Angle Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fuel injection devices with small inter-injection hole angles and short distances between outlet openings are prone to the Coanda effect, leading to deteriorated fuel spray robustness, increased unburned fuel, and decreased fuel economy, especially under varying atmospheric pressures and temperatures.
Innovation Solution
The fuel injection device is designed with injection holes that satisfy specific relationships between inter-injection hole angles and taper angles, minimizing the influence of the Coanda effect by setting these angles based on the average fuel pressure, thereby reducing spray collisions and promoting atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inter-injection hole angle is set small and the distance between outlet openings is set short, then the number of injection holes can be increased, but the Coanda effect increases causing spray attraction and deteriorated atomization
Solution Approach 1:
The patent applies parameter changes by optimizing the inter-injection hole angle and taper angle relationship. Specifically, it sets the inter-injection hole angle to be not less than the sum of the taper angles plus a pressure-dependent term (0.5×P^0.6), where P is the average fuel pressure. This parameter optimization prevents excessive Coanda effect while maintaining multiple injection holes, thereby resolving the contradiction between increasing hole quantity and maintaining spray reliability.
2Shape
If the taper angle is set large to achieve atomization, then fuel spray spreads away from central axis, but the Coanda effect is enhanced causing spray collision and increased unburned fuel
Solution Approach 1:
The patent resolves this contradiction by establishing a quantitative relationship between the inter-injection hole angle and the sum of taper angles. By setting the inter-injection hole angle to be not less than the sum of taper angles plus 0.5×P^0.6, the patent optimizes the balance between spray atomization (achieved through taper angles) and Coanda effect mitigation (achieved through adequate inter-injection hole angle), thereby preventing spray collision and reducing unburned fuel.
3Volume of moving object
If the inter-injection hole angle is minimized for compact design, then device size is reduced, but spray robustness against pressure and temperature variations deteriorates
Solution Approach 1:
The patent addresses this contradiction by introducing a pressure-dependent parameter relationship. The inter-injection hole angle is set to be not less than the sum of taper angles plus 0.5×P^0.6, where P represents average fuel pressure. This dynamic parameter setting allows the nozzle to maintain compact size while ensuring spray robustness across varying pressure and temperature conditions, as the relationship adapts to different operating pressures.
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
This design enhances the robustness of the fuel spray against pressure and temperature variations, reduces unburned fuel, and improves fuel economy by minimizing the Coanda effect's impact on the fuel injection process.
Implementation Method 1
sprays of the fuel injected from the injection holes may be attracted to each other due to the Coanda effect
Data Source
AI summary
Among all combinations of two injection holes, in a combination in which when the injection holes are offset such that their central axes are coincident with each other in inlet openings, an inter-injection hole angle formed by the central axes is minimized, the inter-injection hole angle between the two injection holes is represented as yamin[deg], taper angles, which are formed by the respective contours of the injection hole inner walls in the cross sections along the virtual planes including the central axes of the two injection holes that allow the inter-injection hole angle to be minimized, are represented as θa1 and θa2[deg], and when fuel is injected from the injection holes, average pressure of the fuel in the fuel passage is represented as P[Mpa], and the injection holes are formed so as to satisfy a relationship: γamin≥θa1+θa2+0.5×P0.6.