Fuel Injector Purging Check for Dribble Reduction
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Solution Overview
Problem
Fuel injectors in internal combustion engines often experience fuel dribble, leading to incomplete combustion and undesirable emissions, as high fuel pressure can result in fuel being delivered after the desired injection time, not atomized, and burning incompletely, which complicates achieving performance and efficiency goals.
Innovation Solution
A fuel injector design with a check assembly that includes a movable purging check and outlet check, allowing for the admission of purging fluid to the fuel passage to purge the sac and reduce fuel dribble by controlling the opening and closing of nozzle outlets and purging fluid passages, ensuring complete fuel atomization and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high fuel pressure is used to promote fuel atomization, then fuel atomization is improved, but fuel dribble increases leading to incomplete combustion and higher emissions
Solution Approach 1:
The purging check opens before the outlet check closes to actively purge residual fuel from the sac and fuel passage. This preliminary action removes fuel that would otherwise dribble out after injection, solving the contradiction by preparing the system in advance to prevent the harmful effect while maintaining high pressure for good atomization.
Solution Approach 2:
The invention converts the harmful effect of high pressure (causing fuel to remain in the sac and dribble) into a beneficial purging mechanism. By using the high pressure differential to drive purging fluid through the passage and actively eject residual fuel, the same high pressure condition that causes the problem becomes part of the solution.
2Object-generated harmful factors
If a purging check is added to the check assembly, then fuel dribble is reduced, but device complexity increases
Solution Approach 1:
The purging check is integrated into the existing check assembly structure, sharing the same housing and actuation mechanism as the outlet check. This merging approach adds the purging function without requiring a completely separate system, thereby reducing the complexity increase that would result from a fully independent purging mechanism.
Solution Approach 2:
The check assembly is designed to perform multiple functions: the outlet check controls fuel injection, while the purging check controls fuel passage purging. Both checks are actuated by the same solenoid and share common structural elements, making the assembly a multi-functional component that reduces overall system complexity compared to separate injection and purging systems.
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 solution effectively eliminates or reduces fuel dribble by purging the fuel passage, leading to improved combustion characteristics, reduced emissions, and enhanced engine performance and efficiency.
Implementation Method 1
a purging fluid passage extending between a purging fluid inlet and a purving fluid outlet that opens to the fuel passage
Implementation Method 2
an outlet check movable within the injector body between a retracted position where the fuel passage is in fluid communication with the set of nozzle outlets, and an advanced position where the outlet check contacts the outlet check seat
Implementation Method 3
relatively high fuel pressure can promote fuel atomization, which in turn tends to be associated with more complete burning of injected fuel
Data Source
AI summary
A fuel system includes a fuel injector having a fuel passage and a purging fluid passage formed therein. A nozzle tip inner surface defines a sac forming a blind end of the fuel passage in the fuel injector. A coaxial concentric check assembly includes a purging check movable to admit a purging fluid such as pressurized air into the fuel passage to purge the sac of fuel. Reduced injector dribble is observed from the purging of fuel.