Waste Gate Valve Control for Cold Engine Startability
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Solution Overview
Problem
Conventional engines equipped with superchargers face challenges in increasing engine speed during cranking, especially in cold starting conditions, due to turbine resistance, which affects startability and stability post-starting.
Innovation Solution
A control apparatus that adjusts the waste gate valve and intake bypass valve based on engine temperature to enhance startability and stability, by opening the waste gate valve during cranking in cold conditions and closing it after startup to maintain exhaust resistance and promote warm-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the waste gate valve is closed during cranking in cold conditions, then exhaust resistance is maintained for better boost pressure, but engine speed cannot be increased sufficiently due to turbine resistance
Solution Approach 1:
The waste gate valve control strategy dynamically changes based on engine temperature and operating condition (cranking vs. post-start). During cranking in cold conditions, the valve is opened to reduce resistance. After startup, it closes to maintain boost pressure. This dynamic adaptation resolves the contradiction between needing high speed during cranking and needing high reliability after startup.
Solution Approach 2:
The system changes the state parameter of the waste gate valve (open/closed) based on temperature and operational phase parameters. This parameter change allows the system to optimize for different priorities: speed during cranking, and reliability/boost pressure after startup.
2Reliability
If the waste gate valve is opened during cranking to increase engine speed, then startability is improved, but boost pressure stability deteriorates
Solution Approach 1:
The control strategy segments the operation into distinct phases (cranking phase and post-start phase), applying different waste gate valve control strategies to each phase. This segmentation allows optimization for startability during cranking without compromising boost pressure stability after startup.
Solution Approach 2:
The waste gate valve is opened in advance during the cranking phase to facilitate engine startup. After startup is achieved, the valve closes to establish stable boost pressure. This preliminary action during cranking prevents startup difficulties without affecting post-start stability.
3Temperature
If the waste gate valve remains closed after startup in cold conditions, then boost pressure is maintained, but engine warm-up time is extended
Solution Approach 1:
The waste gate valve control dynamically transitions from closed (for boost pressure) to open (for warm-up) based on the engine warm-up state. This dynamic adjustment reduces warm-up time while maintaining adequate boost pressure control.
Solution Approach 2:
The system employs periodic or conditional opening of the waste gate valve after startup to promote exhaust gas flow and heat transfer, accelerating warm-up without completely sacrificing boost pressure control.
Data Source
AI summary
Upon request for start-up of an engine, a control apparatus controls the opening/closing action of a waste gate valve in accordance with the temperature Te of the engine before cranking and, if the temperature Te of the engine is equal to or lower than a first set temperature Te1, sets the waste gate valve in an open state.