Gasoline Direct-Injection Engine Control Device for Retarded Ignition
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Solution Overview
Problem
Gasoline direct-injection engines face challenges in retarding ignition timing without causing misfires, especially at higher compression ratios, due to excessive in-cylinder temperature decrease during the expansion stroke, which can lead to vibration noise and soot generation.
Innovation Solution
A control device for gasoline direct-injection engines that employs a multi-stage injection strategy, including pre-injection and post-injection, where fuel is distributed radially peripherally and centrally within the cylinder to control temperature and oxidative reactions, ensuring ignition occurs after the compression top dead center and maintaining optimal in-cylinder conditions for retarded combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ignition timing is retarded to reduce pressure increase rate and vibration noise, then NVH level is reduced, but in-cylinder temperature decreases excessively causing misfire
Solution Approach 1:
The fuel injection is divided into multiple stages (pre-injection, post-injection, and main injection) with distinct purposes. Pre-injection occurs before compression to prepare fuel in the periphery, post-injection occurs after compression to provide additional fuel to the center, and main injection provides the bulk fuel. This segmentation allows temperature management across different phases of the cycle, enabling retarded ignition timing while maintaining combustion stability.
Solution Approach 2:
Pre-injection is performed during the compression stroke before the main combustion event. This preliminary fuel injection allows the fuel to be present in the radially peripheral section before ignition, creating a staged combustion process. The preliminary preparation of fuel distribution enables the combustion to proceed reliably even when the main ignition timing is retarded into the expansion stroke.
2Loss of energy
If compression ratio is increased to improve thermal efficiency, then fuel efficiency is improved, but in-cylinder temperature decreases faster during expansion stroke limiting ignition timing retard
Solution Approach 1:
Different regions of the combustion chamber are targeted with different injection strategies. The radially peripheral section receives fuel from pre-injection, while the radially central section receives fuel from post-injection. This local differentiation of fuel distribution allows the high compression ratio to be utilized for thermal efficiency while the staged combustion maintains sufficient temperature at the center for reliable ignition even with retarded timing.
Solution Approach 2:
The injection timing, duration, and quantity are dynamically adjusted across multiple stages. Pre-injection timing is set during compression, post-injection timing is set after compression top dead center, and the injection quantities are optimized for each stage. These parameter changes enable the system to maintain combustion stability with high compression ratios while achieving extended ignition timing retard for noise reduction.
3Adaptability or versatility
If multi-stage injection is implemented to control fuel distribution, then combustion control is improved, but device complexity increases
Solution Approach 1:
A single injector is designed to perform multiple injection functions (pre-injection, post-injection, and main injection) by varying the injection timing and duration controlled by the engine control unit. This multi-functional approach achieves complex fuel distribution patterns and combustion control without requiring multiple separate injection systems, thereby limiting the increase in device complexity while maintaining high adaptability.
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 extends the period for which ignition timing can be retarded, reducing vibration noise and soot generation while preventing misfires by managing in-cylinder temperature and fuel distribution effectively.
Implementation Method 1
when the fuel is injected, due to the Coanda effect, a negative pressure area is created near the nozzle port
Implementation Method 2
at a timing for the fuel injected in the post injection to ignite is after an oxidative reaction of the fuel injected in the pre-injection occurs
Implementation Method 3
the engine controls a combustion timing so that a timing at which the pressure increase rate during motoring of the engine becomes a largest
Data Source
AI summary
A control device of a gasoline direct-injection engine is provided. The control device includes an engine body, an injector, and a controller. Within a high load operating range, the controller causes the injector to perform a pre-injection and a post injection. In the pre-injection, the fuel is injected to cause a fuel concentration within an in-cylinder radially peripheral section to be higher than a fuel concentration within an in-cylinder radially central section at a timing for the fuel to ignite. In the post injection, the fuel is injected to cause the fuel concentration within the radially central section to be higher than the fuel concentration within the radially peripheral section at a timing for the fuel to ignite. The timing for the fuel injected in the post injection to ignite is after an oxidative reaction of the fuel injected in the pre-injection occurs and after a compression top dead center.