Wankel Stator Insert with Pilot Subchamber for Heavy Fuel Ignition
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Solution Overview
Problem
Existing rotary internal combustion engines, such as Wankel engines, are not optimized for use in compound cycle systems or with heavy fuels like kerosene, leading to inefficiencies in combustion and ignition.
Innovation Solution
The design incorporates a rotary internal combustion engine with a specific insert configuration that includes a pilot fuel injector and a main fuel injector, along with a subchamber for pilot fuel injection, to create a lean mixture and enhance ignition stability, particularly for heavy fuels, using materials with high heat resistance and strategically positioned ignition elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single fuel injector or two spaced apart fuel injectors are used in conventional rotary engines, then the engine structure is simple, but combustion efficiency and ignition stability are insufficient for heavy fuels
Solution Approach 1:
The fuel injection system is segmented into two separate injectors: a pilot fuel injector and a main fuel injector. The pilot injector introduces a small amount of fuel early in the compression stroke to create a stable ignition zone, while the main injector delivers the bulk fuel later. This segmentation allows each injector to perform its specific function optimally, improving ignition stability for heavy fuels without requiring an overly complex integrated system
Solution Approach 2:
The pilot fuel injector performs preliminary action by injecting a small amount of fuel into the combustion chamber during the compression stroke, before the main fuel injection occurs. This preliminary fuel injection creates a stable ignition zone that prepares the combustion environment for the subsequent main fuel injection, ensuring reliable ignition of heavy fuels which have poor ignition characteristics
2Productivity
If conventional fuel injection arrangements are used, then the engine design is simple, but combustion efficiency is insufficient for compound cycle systems and heavy fuels
Solution Approach 1:
The insert configuration incorporates locally optimized features including a specifically shaped subchamber for the pilot injector, strategically positioned pilot and main injectors, and an ignition member positioned to maximize combustion efficiency. These local quality improvements in the insert design enhance overall combustion efficiency for compound cycle systems without requiring complete redesign of the entire engine
Solution Approach 2:
The insert acts as an intermediary component that bridges the combustion chamber and the fuel injection/ignition system. It provides a structured environment with a subchamber for pilot fuel mixing, positions the ignition member optimally, and coordinates the timing and location of both fuel injections. This intermediary structure enables efficient combustion of heavy fuels in compound cycle systems
3Reliability
If fuel injectors are located in a recess adjacent the combustion chamber, then the ignition system is simple to implement, but ignition stability for heavy fuels is insufficient
Solution Approach 1:
The pilot fuel injector is nested within a subchamber that is itself part of the insert structure, which is located in the peripheral wall of the combustion chamber. This nested arrangement allows the pilot fuel to be introduced into a confined space where it can mix with air and create a stable ignition zone before the main fuel injection occurs, improving ignition stability for heavy fuels
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 configuration improves combustion efficiency and stability, especially when using heavy fuels, by creating a stable and powerful ignition zone and optimizing the combustion process for heavy fuels like diesel or kerosene, enhancing the engine's performance in compound cycle systems.
Implementation Method 1
a pilot fuel injector and a main fuel injector, along with a subchamber for pilot fuel injection, to create a lean mixture and enhance ignition stability
Data Source
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AI summary
A Wankel engine (10) has an insert (34) in the peripheral wall of the stator (18). The insert (34) is made of a material having a greater heat resistance than that of the peripheral wall (18) and has a subchamber (72) defined therein and an inner surface (66) bordering the engine cavity (20). The subchamber communicates with the cavity (20) through at least one opening (174), which is defined in the inner surface (66) and has a shape forming a reduced cross-section adjacent the opening (74). A pilot fuel injector (78) has a tip (80) received in the subchamber (72). An ignition element (84) has a tip (86) received in the subchamber (72). A main fuel injector (42) extending through the peripheral wall (18) and has a tip (44) communicating with the cavity (20) at a location spaced apart from the insert (34).