Fuel Injector Eccentric Spreading Section Design
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Solution Overview
Problem
In fuel injectors for gasoline engines, the spray penetration is affected by the diameter and length of injection holes, leading to potential obstruction and interference with the wall surface, which can result in inadequate fuel spray generation and atomization performance due to the need for optimizing the shape and thickness of the valve seat plate.
Innovation Solution
The fuel injector incorporates a spreading section with a counter bore on the outlet end and a non-parallel or oblong shape to ensure the minimum thickness of the valve seat plate while preventing spray obstruction, maintaining the spray's penetration and linearity without increasing the injection hole length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the injection hole diameter is increased to increase fuel flow rate and momentum, then spray penetration is improved, but the valve seat plate thickness is reduced and spray may be obstructed by the wall surface
Solution Approach 1:
The patent introduces a counterbore structure that creates a stepped configuration in the injection hole, adding a radial dimension change. This allows the spray to expand perpendicular to the flow direction, improving atomization and penetration without requiring a longer injection hole that would reduce plate thickness. The counterbore provides additional space for spray development in a different spatial dimension.
Solution Approach 2:
The injection hole is divided into multiple sections: a first portion with a first diameter, a second portion with a second diameter (forming the counterbore), and potentially a third portion. This segmentation allows each section to serve a specific function - the first portion maintains structural integrity, while the second portion provides spray expansion space, resolving the conflict between penetration and thickness.
2Length of moving object
If the injection hole length is increased to improve fuel linearity and reduce air entrainment, then spray penetration is improved, but the valve seat plate thickness is reduced
Solution Approach 1:
Instead of extending the injection hole length axially (which would reduce plate thickness), the patent uses a counterbore to provide additional volume in the radial direction. This allows the spray to develop better linearity and reduce air entrainment through the stepped geometry without compromising the minimum plate thickness requirement.
3Productivity
If the valve seat plate thickness is reduced to accommodate larger injection holes, then fuel flow rate is improved, but spray may be obstructed by the wall surface
Solution Approach 1:
The counterbore creates a stepped structure that provides additional radial space for spray expansion. This allows larger injection hole diameters (improving fuel flow rate) without the spray being obstructed by the wall surface, as the counterbore provides a buffer zone before the spray exits into the combustion chamber.
Solution Approach 2:
The counterbore acts as an intermediary structure between the injection hole and the combustion chamber. It provides a transition zone that allows the spray to expand and develop properly before exiting, preventing direct obstruction by the wall surface while maintaining structural integrity of the valve seat plate.
Data Source
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AI summary
To provide a fuel injector having a plurality of injection holes (112) injecting fuel into a combustion chamber of a gasoline engine in which each of the plurality of injection holes includes a guide section (114) to determine an injection direction and an injection amount of the fuel passing therethrough and a spreading section (116) to change a state of the fuel passing through the guide section to a spray state, and at least one of the plurality of injection holes is configured such that a central axis (118b) of the spreading section is parallel to a central axis (118a) of the guide section while being formed eccentrically on a side farther from a central axis (120) of the fuel injector than the central axis of the guide section.