Engine Control System Using Tumble Flow for Cold Start Combustion
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Solution Overview
Problem
Conventional spark-ignition direct-injection engines face challenges in maintaining combustion stability and preventing fuel adhesion to the piston, which degrades emission performance and ignition stability, especially during cold starts when the catalyst temperature is low.
Innovation Solution
A control system that utilizes a tumble flow to manage fuel injection timing and direction within the combustion chamber, splitting fuel injections into intake-stroke, compression-stroke-early-half, and compression-stroke-latter-half timings, with the fuel injected towards the vortex center at the early-half timing to prevent adhesion and ensure a rich area around the ignition plug at the appropriate timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is injected in the latter half of compression stroke to form a rich atmosphere around the ignition plug, then combustion stability is improved, but fuel adhesion to the piston increases which degrades emission performance
Solution Approach 1:
The fuel injection timing is segmented into three distinct phases: intake stroke injection, early half compression stroke injection, and latter half compression stroke injection. This segmentation allows each injection to serve a specific function - the early half injection forms the rich atmosphere while the latter half injection supplements it without causing excessive adhesion, as the tumble flow has already positioned the fuel-rich mixture toward the ignition plug.
Solution Approach 2:
Fuel is injected during the early half of the compression stroke to create a rich atmosphere around the ignition plug before ignition occurs. This preliminary action ensures that when ignition happens, the fuel mixture is already positioned and concentrated in the appropriate location, improving combustion stability without requiring excessive fuel injection that would cause adhesion problems.
2Temperature
If ignition timing is retarded to after CTDC to increase catalyst temperature, then catalyst warm-up is accelerated, but combustion stability degrades
Solution Approach 1:
Fuel is injected during the early half of the compression stroke to create a rich atmosphere around the ignition plug before ignition occurs. This preliminary action ensures that when ignition happens, the fuel mixture is already positioned and concentrated in the appropriate location, improving combustion stability without requiring excessive fuel injection that would cause adhesion problems.
Solution Approach 2:
The system changes the timing parameters of fuel injection to match the retarded ignition timing. By injecting fuel in the early half of compression stroke and using tumble flow to position it, the system maintains optimal combustion conditions even with post-CTDC ignition, allowing catalyst warm-up without sacrificing combustion stability.
3Object-generated harmful factors
If fuel injection amount in the latter half of compression stroke is reduced to suppress fuel adhesion, then emission performance is improved, but the rich atmosphere around the ignition plug cannot be sufficiently formed, degrading combustion stability
Solution Approach 1:
The fuel injection timing is segmented into three distinct phases: intake stroke injection, early half compression stroke injection, and latter half compression stroke injection. This segmentation allows each injection to serve a specific function - the early half injection forms the rich atmosphere while the latter half injection supplements it without causing excessive adhesion, as the tumble flow has already positioned the fuel-rich mixture toward the ignition plug.
Solution Approach 2:
The tumble flow acts as an intermediary mechanism that transfers and positions the fuel mixture. By injecting fuel in the early half of compression stroke and using the tumble flow to move it toward the ignition plug, the system can maintain a rich atmosphere without requiring excessive fuel injection that would cause adhesion problems.
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 enhances combustion stability while reducing fuel adhesion to the piston and combustion chamber surfaces, thereby improving emission performance and maintaining catalyst temperature for effective exhaust gas purification.
Implementation Method 1
a tumble flow generator for generating the tumble flow within the combustion chamber
Implementation Method 2
a fuel injector for directly injecting the fuel into the combustion chamber
Implementation Method 3
an ignition plug of the engine to ignite after a top dead center on compression stroke
Data Source
AI summary
A control system of an engine is provided, which controls, by using a tumble flow, a behavior of fuel that is directly injected into a combustion chamber formed inside a cylinder of the engine. The control system includes a fuel injector for directly injecting the fuel into the combustion chamber, a tumble flow generator for generating the tumble flow within the combustion chamber, an ignition timing control module for controlling an ignition plug to ignite after a top dead center on compression stroke of the cylinder in a cold state of the engine, and a fuel injector control module for controlling the fuel injector to inject the fuel at an intake-stroke injection timing, a compression-stroke-early-half injection timing, and a compression-stroke-latter-half injection timing. The fuel injector control module controls the fuel injector to inject the fuel toward a vortex center of the tumble flow at the compression-stroke-early-half injection timing.