Fuel Injector Port Eccentric Step Surface Atomization
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Solution Overview
Problem
Existing fuel injectors face challenges in achieving efficient atomization and directivity of fuel spray due to fuel being attracted to stepped surfaces and varying flow directions caused by concave structures, leading to fuel deposits and reduced atomization.
Innovation Solution
A fuel injector design featuring a valve nozzle with a fuel-injection port that is inclined toward the periphery, where the upstream and downstream portions form a step surface eccentric to the center line, minimizing fuel attraction to the step surface and maintaining consistent flow direction through straight passages with varying diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a concave structure is used in the injection hole plate to improve atomization, then fuel atomization is improved, but the fuel flow direction is varied and directivity of fuel spray deteriorates
Solution Approach 1:
The fuel injection port is divided into an upstream portion and a downstream portion with different functions. The upstream portion has a larger diameter for fuel reception, while the downstream portion has a smaller diameter for controlled injection. This segmentation allows each portion to be optimized independently for its specific function.
Solution Approach 2:
The fuel injection port is designed with asymmetric dimensions where the diameter in the fuel flow direction is larger than the diameter in the radial direction. This asymmetric geometry creates a specific flow pattern that maintains fuel spray directivity while improving atomization quality through controlled flow expansion.
2Productivity
If a stepped surface is formed between the injection hole and concave at acute angle to facilitate fuel flow, then fuel flow is improved, but fuel is attracted to the stepped surface forming deposits that restrict atomization
Solution Approach 1:
The transition between the upstream and downstream portions is designed with a curved surface instead of a sharp stepped surface. This curved geometry eliminates acute angles where fuel could accumulate and form deposits, while still providing the necessary flow transition. The curved surface allows smooth fuel flow without creating attachment points for fuel deposits.
3Shape
If the fuel-injection port is inclined outwardly to improve spray distribution, then fuel spray directivity is improved, but the complex geometry makes it difficult to prevent fuel deposits on stepped surfaces
Solution Approach 1:
The fuel injection port is designed with different local characteristics: the upstream portion has a larger diameter for fuel reception and the downstream portion has a smaller diameter for injection. The curved transition surface provides local quality variation that facilitates smooth flow while preventing deposits. This localized optimization achieves spray distribution improvement without excessive geometric complexity.
Data Source
AI summary
A fuel injector has a valve nozzle defining a fuel-injection port downstream of a fuel passage. The fuel-injection port is inclined toward a nozzle periphery from a fuel-inlet to a fuel-outlet. A valve needle is capable of moving in a valve-opening direction to open the fuel-injection port so that a fuel flowing into the fuel-inlet from the nozzle periphery is injected into an internal combustion engine. The fuel-injection port has an upstream-portion defining the fuel-inlet, and a downstream-portion defining the fuel-outlet. The downstream-portion is smoothly connected to the upstream-portion at a position most close to a center of the valve nozzle, and the downstream-portion is offset toward the nozzle periphery relative to the upstream-portion, so that the upstream-portion and the downstream-portion forms a step surface therebetween. The step surface is eccentric to a center line of the upstream-portion.