Engine Control Unit Valve Overlap and Port Injection Coordination
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Solution Overview
Problem
Conventional engine control methods fail to effectively prevent fuel blow-by during valve overlap, leading to decreased engine output and environmental performance, especially in operating states involving homogeneous combustion, and are limited by restrictions on fuel injection volume and turbocharger operation.
Innovation Solution
A control unit for internal combustion engines that adjusts both port injection volume and valve overlap period based on direct injection volume, utilizing a changer to increase port injection volume and reduce overlap period when direct injection volume decreases, and includes a turbocharger detector to optimize fuel injection and charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the valve overlap period is increased to improve scavenging efficiency and engine output, then the charging efficiency and engine output are improved, but fuel blow-by occurs more often where intake air flows directly into the exhaust path
Solution Approach 1:
The control device dynamically adjusts the valve overlap period based on operating conditions. When fuel blow-by is detected or anticipated (during homogeneous combustion with port injection), the overlap period is reduced to prevent fuel from flowing directly to the exhaust. When blow-by is less likely (during stratified combustion with direct injection only), the overlap period is increased to maximize scavenging efficiency and engine output.
Solution Approach 2:
The system transitions from a static valve overlap setting to a dynamic one that changes based on combustion mode and operating conditions. The control device monitors injection mode and adjusts valve timing in real-time, making the valve overlap period adaptive rather than fixed, allowing optimization of both power output and fuel containment.
2Object-generated harmful factors
If port injection is inhibited to prevent fuel blow-by, then fuel blow-by is reduced, but the control becomes inapplicable in operating states involving homogeneous combustion
Solution Approach 1:
Instead of a static prohibition of port injection, the system dynamically controls port injection based on combustion mode detection. During homogeneous combustion, port injection is permitted but the valve overlap is reduced to prevent blow-by. During stratified combustion, port injection may be inhibited or reduced. This dynamic approach allows the system to adapt to different operating states while preventing fuel blow-by.
Solution Approach 2:
The control device changes the valve overlap period parameter based on the detected combustion mode and injection strategy, rather than simply inhibiting port injection. This parameter adjustment allows homogeneous combustion to proceed with port injection while preventing fuel blow-by through optimized valve timing.
3Quantity of substance
If the direct injection volume decreases due to fuel pressure decline or deposit accumulation, then the actual fuel supply is reduced, but increasing the control command value does not lead to an increase in actual injection volume due to limited injection period
Solution Approach 1:
The control device monitors actual fuel injection volume and compares it with the commanded volume. When direct injection volume decreases due to fuel pressure decline or deposit accumulation, the system detects this discrepancy and compensates by adjusting port injection volume to make up the difference, ensuring total fuel supply meets requirements.
Solution Approach 2:
The system combines direct injection and port injection to ensure adequate total fuel supply. When direct injection volume is insufficient, port injection is increased to compensate. This merging of two injection systems provides redundancy and ensures fuel supply requirements are met even when one system underperforms.
4Quantity of substance
If the port injection volume is increased to compensate for decreased direct injection volume, then the total fuel supply is maintained, but this works against the regulation of fuel blow-by
Solution Approach 1:
The control device dynamically adjusts both port injection volume and valve overlap period based on real-time conditions. When direct injection volume decreases, port injection is increased to compensate for fuel supply, but simultaneously the valve overlap period is reduced to prevent fuel blow-by. This dynamic coordination of multiple parameters allows the system to maintain total fuel supply while preventing harmful blow-by effects.
Solution Approach 2:
The system changes multiple parameters simultaneously - increasing port injection volume while reducing valve overlap period - to achieve the dual objective of maintaining total fuel supply and preventing fuel blow-by. This coordinated parameter adjustment resolves the contradiction between fuel supply and blow-by prevention.
Data Source
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AI summary
Provided is a control unit (1) for an internal combustion engine (10) including a direct injector (11) directly injecting fuel into a cylinder (20) and a port injector (12) injecting fuel into an intake port (17). The control unit (1) includes an injection volume calculator (5) to calculate a volume of the fuel injected from the direct injector (11), a port injection controller (2) to control a volume of the fuel injected from the port injector (12), an overlap period controller (4) to control an overlap period during which both an intake valve (27) and an exhaust valve (28) are open, and a changer (6) to vary both the volume of the port injection from the port injector (12) and the overlap period based on the volume of the direct injection.