Engine Control Device for Supercharged Engine Blow-by Suppression
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Solution Overview
Problem
Engines with a combination of cylinder and port injections experience blow-by issues during valve overlap periods, particularly when supercharged, leading to reduced engine output and exhaust performance, as fuel from port injection passes through the cylinder and into the exhaust path.
Innovation Solution
An engine control device that adjusts fuel injection timings and valve overlap periods based on engine load, using a variable valve actuating mechanism to extend valve overlap and retard port injection timing, thereby suppressing blow-by and optimizing both injection schemes for improved scavenging efficiency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the valve overlap period is extended to improve scavenging efficiency and volumetric efficiency, then engine output is improved, but blow-by occurs causing fuel to enter the exhaust path and reducing engine output and exhaust performance
Solution Approach 1:
The patent applies dynamics by making the valve overlap period variable rather than fixed. The control device adjusts the duration of the valve overlap period based on engine operating conditions (load, speed). Under high load conditions where blow-by is problematic, the valve overlap period is reduced or eliminated. Under low load conditions where scavenging efficiency is prioritized, the valve overlap period is extended. This dynamic adjustment resolves the contradiction between improving engine output through extended valve overlap and preventing blow-by that reduces output and exhaust performance.
Solution Approach 2:
The patent changes the parameter of valve overlap period duration based on operating conditions. The control device monitors engine load and speed, and accordingly adjusts the valve overlap period parameter. When engine load is high and supercharging pressure is high (conditions promoting blow-by), the valve overlap period is reduced or set to zero. When engine load is low and scavenging efficiency is more important, the valve overlap period is extended. This parameter change approach directly resolves the technical contradiction by optimizing the valve overlap period for different operating regimes.
2Productivity
If port injection is used during homogeneous combustion to improve fuel distribution, then combustion efficiency is improved, but fuel adheres to intake pipe walls reducing available fuel for combustion
Solution Approach 1:
The patent applies dynamics by dynamically switching between port injection and cylinder injection modes based on engine load conditions. During high load operations where homogeneous combustion is desired, port injection is used to achieve uniform fuel distribution and improve combustion efficiency. During low load operations where fuel economy and preventing wall adherence are critical, the system switches to cylinder injection (stratified charge combustion) which injects fuel directly into the cylinder, minimizing fuel contact with intake pipe walls and reducing fuel loss. This dynamic mode switching resolves the contradiction between improving combustion efficiency through port injection and preventing fuel loss on intake pipe walls.
3Reliability
If cylinder injection is used during stratified charge combustion to ensure sufficient fuel supply, then combustion reliability is improved, but device complexity increases due to additional injection system requirements
Solution Approach 1:
The patent applies universality by designing the injection system to perform multiple functions through a single integrated system. The injection system can operate in two modes: port injection for homogeneous combustion and cylinder injection for stratified charge combustion. The control device selectively activates the appropriate injection mode based on engine operating conditions. This multi-functionality allows the system to achieve reliable combustion under various conditions (both high load and low load) without requiring completely separate injection systems, thereby improving combustion reliability while limiting the increase in device complexity through shared hardware resources.
Data Source
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AI summary
An engine control device (1) for an engine provided with a supercharger (30), including a cylinder injection valve (11), a port injection valve (12), and a variable valve actuating mechanism (40). The device includes an injection controller (3) that controls injections of fuel through the cylinder injection valve (11) and through the port injection valve (12), on the basis of a load P on the engine (10), and a variable valve controller (5) that controls the variable valve actuating mechanism (40) on the basis of the load P. The variable valve controller (5) provides a valve overlap period in an operating state where the load P is equal to or greater than a first predetermined value P1. The injection controller (3), in the operating state where the load P is equal to or greater than the first predetermined value P1, carries out a cylinder injection and a port injection, and in an operating state where the load P is equal to or greater than a second predetermined value P2 that is greater than the first predetermined value P1, retards timing for injecting the fuel through the port injection valve (12), relative to the timing for injecting the fuel in an operating state where the load P is less than the second predetermined value P2.