Multi-hole Nozzle Jet Orientation for Two-stroke Engine
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Solution Overview
Problem
In two-stroke internal combustion engines, existing fuel injection systems often result in fuel wetting the piston and cylinder walls due to insufficient evaporation time and momentum, leading to hydrocarbon emissions and disrupted air flow, especially at low loads.
Innovation Solution
A multi-hole low-pressure nozzle with a nozzle plate having openings arranged within an enveloping circle, forming a common nozzle jet with a controlled opening angle, which minimizes the risk of the nozzle jet hitting the cylinder wall by ensuring a maximum inclination angle of 20° with the cylinder jacket, allowing for efficient fuel distribution without disrupting the air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-hole nozzle is used to distribute fuel over a large area, then fuel distribution is improved, but the opening angle must be increased which risks applying the nozzle jet to the cylinder wall
Solution Approach 1:
The single-hole nozzle is segmented into multiple nozzle holes arranged within an enveloping circle. This segmentation allows the fuel to be distributed over a large area through multiple smaller jets that merge into a common nozzle jet, achieving wide fuel distribution without requiring a large opening angle that would risk cylinder wall contact.
Solution Approach 2:
The nozzle holes are arranged in a circular pattern within an enveloping circle, transitioning from a single-dimensional linear spray to a two-dimensional circular distribution pattern. This dimensional change enables broader fuel coverage area while maintaining a controlled opening angle, as the circular arrangement naturally distributes the jet directions in multiple directions without requiring excessive angular spread from each individual hole.
2Quantity of substance
If the nozzle jet opening angle is increased to distribute fuel over a larger area, then fuel distribution is improved, but the risk of the nozzle jet being applied to the cylinder wall increases
Solution Approach 1:
By dividing the single large-angle jet into multiple smaller-angle jets from individual nozzle holes, the overall fuel distribution area is expanded without increasing the opening angle of each individual jet. The multiple jets merge to form a common nozzle jet that covers a large area while each component jet maintains a safe, limited opening angle.
Solution Approach 2:
Multiple individual nozzle jets from the segmented nozzle holes are merged to form a single common nozzle jet with a large effective distribution area. This merging allows the system to achieve the benefit of wide fuel distribution while each individual jet component maintains a controlled, safe opening angle that prevents cylinder wall contact.
3Power
If fuel is injected with high momentum to overcome air flow disruption, then fuel injection effectiveness is improved, but the flushing flow of fresh air is disrupted especially at low loads
Solution Approach 1:
The single high-momentum injection jet is segmented into multiple lower-momentum jets from individual nozzle holes. These multiple jets collectively deliver the required fuel quantity while each individual jet has reduced momentum that causes less disruption to the fresh air flushing flow, particularly at low load conditions where air flow velocity is lower.
Solution Approach 2:
The injection parameters are changed from a single high-momentum jet to multiple lower-momentum jets. This parameter change maintains the overall fuel delivery effectiveness while reducing the disruptive impact on the fresh air front velocity, as the distributed lower-momentum jets cause less turbulence and interference with the air flow pattern.
4Object-affected harmful factors
If the nozzle jet opening angle is limited to prevent cylinder wall contact, then cylinder wall wetting is prevented, but the fuel distribution area is reduced
Solution Approach 1:
The limited-opening-angle nozzle jets are segmented and arranged in a circular pattern within an enveloping circle. This segmentation allows multiple jets with limited individual opening angles to collectively cover a large fuel distribution area, as the circular arrangement distributes the jets in multiple directions without requiring any single jet to have a large opening angle.
Solution Approach 2:
The fuel distribution transitions from a single-dimensional linear pattern to a two-dimensional circular pattern through the enveloping circle arrangement. This dimensional change enables the system to achieve large fuel distribution area with limited opening angles, as the circular geometry naturally expands the coverage area by distributing jets in radial directions rather than requiring a single jet to spread at a large angle.
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 achieves a balanced fuel distribution with reduced impulse, preventing fuel from reaching the cylinder walls and maintaining a clean combustion chamber, thereby reducing hydrocarbon emissions and ensuring effective flushing flow.
Implementation Method 1
multi-hole low-pressure nozzle which inject the fuel with reduced momentum
Implementation Method 2
the velocity vector of the nozzle jet in the direction of the nozzle axis and the velocity vector of the flushing air flow in the flow main direction
Data Source
AI summary
A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle (α) dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle (γ) of 20°.