Asymmetric Injection Nozzle for Combustion Chamber Wall Wetting
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Solution Overview
Problem
In spark-ignited piston engines with direct injection, achieving efficient and low-emission combustion while minimizing the wetting of combustion chamber walls with liquid fuel is challenging, especially in smaller engines where reduced cubic capacity limits fuel distribution and increases pollutant emissions.
Innovation Solution
The design of an injection nozzle with adjacent injection jets that interact to deviate their propagation direction, reducing penetration depth by adjusting the angular distance between jets and optimizing spray hole geometry, pressure conditions, and flow patterns to minimize wall wetting and enhance mixture formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the penetration depth of injection jets is increased to improve fuel distribution in small displacement engines, then mixing efficiency is improved, but the risk of combustion chamber wall wetting increases
Solution Approach 1:
The injection nozzle employs asymmetric angular spacing between adjacent spray holes, where at least one pair of adjacent spray holes has a smaller angle between their longitudinal center axes than the angle between a spray hole and its adjacent spray hole in the circumferential direction. This asymmetric arrangement creates interacting injection jets that deviate toward each other, reducing penetration depth and preventing wall wetting while maintaining effective fuel distribution.
Solution Approach 2:
The invention changes the angular parameter (angle between longitudinal center axes of adjacent spray holes) to optimize injection jet behavior. By adjusting this geometric parameter, the penetration depth of injection jets is controlled, and jet interaction is enhanced to reduce the risk of combustion chamber wall wetting while maintaining effective fuel distribution.
2Use of energy by moving object
If the cubic capacity of the engine is reduced to lower fuel consumption, then fuel efficiency is improved, but the free propagation paths for injection jets are reduced, worsening fuel distribution
Solution Approach 1:
In small displacement engines, the asymmetric angular spacing of spray holes creates interacting injection jets that spread fuel more effectively within the limited combustion chamber space. The deviation of jets toward each other enhances mixing efficiency and ensures adequate fuel distribution despite reduced free propagation paths.
Solution Approach 2:
The invention optimizes the angular parameters of spray hole arrangement specifically for small displacement engines, adjusting the angles between longitudinal center axes to maximize fuel distribution effectiveness within constrained geometric boundaries while maintaining low fuel consumption.
3Ease of manufacture
If the angles between longitudinal center axes of adjacent spray holes are made equal to simplify design, then manufacturing is easier, but injection jet interaction is reduced, increasing wall wetting risk
Solution Approach 1:
The invention deliberately introduces asymmetric angular spacing between spray holes to create beneficial injection jet interaction. By making at least one pair of adjacent spray holes have a smaller angle between their longitudinal center axes, the jets are positioned closer together to enhance mutual interaction and deviation, effectively reducing wall wetting risk despite the increased design complexity.
Solution Approach 2:
The invention changes the angular parameters of spray hole arrangement from equal spacing to asymmetric spacing, optimizing the angles between longitudinal center axes to enhance injection jet interaction and reduce the risk of combustion chamber wall wetting.
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 approach reduces the risk of combustion chamber wall wetting, achieves favorable mixture formation, and improves stratified charging and ignition efficiency, thereby reducing fuel consumption and emissions.
Implementation Method 1
an individual injection jet interacts with the fresh air surrounding it in such a way that the fresh air compresses the respective injection jet transversely to its direction of propagation towards its center and counteracts an expansion of the injection jet transversely to its direction of propagation
Data Source
AI summary
The present invention relates to an injection nozzle (3) for the direct injection of a liquid fuel into a cylinder chamber (4) of a piston engine (1), preferably spark-ignited, having a plurality of injection holes (8) for producing injection jets (9), which are arranged distributed on a nozzle body (10) of the injection nozzle (3) in the circumferential direction. Reduced harmful emissions can be achieved when at least one pair (12) of injection holes (8) adjoining in a circumferential direction is provided, the longitudinal centre axes (13) of which include a pair angle (14) in the circumferential direction that is smaller than an adjacent angle (15) which is included in the circumferential direction between the longitudinal centre axis (13) of the respective injection hole (8) of the injection hole pair (12) and a longitudinal centre axis (13) of an injection hole (8) adjacent to the injection hole pair (12) in the circumferential direction.