Adaptive Fuel Pressure Control for Engine Restart Reliability
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Solution Overview
Problem
In internal combustion engines with automatic start-stop systems, reducing rail pressure when the engine is switched off can lead to delayed restarts and excessive loading of hydraulic components.
Innovation Solution
The fuel pressure in the common rail system is controlled to a first value when the engine is switched off, which is typically an idle pressure, and to a second value, usually atmospheric pressure, when the driver indicates vehicle shutdown, thereby preventing pressure from dropping below a threshold and allowing quicker engine restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rail pressure is reduced to atmospheric pressure when the internal combustion engine is switched off, then the hydraulic components are less stressed, but the restarting of the internal combustion engine is considerably delayed
Solution Approach 1:
The patent applies dynamics by making the pressure control strategy adaptive rather than static. The control unit dynamically adjusts the rail pressure management based on the detected shutdown cause: maintaining higher pressure for start-stop operations while reducing pressure for permanent shutdowns. This dynamic adaptation resolves the contradiction by optimizing pressure levels according to the specific operational context, ensuring quick restart when needed while reducing stress during permanent shutdown.
Solution Approach 2:
The patent changes the pressure parameter based on different operational conditions. By detecting the shutdown cause and adjusting the target pressure level accordingly (maintaining higher pressure for start-stop, reducing to atmospheric for permanent shutdown), the system optimizes both restart performance and component stress reduction. This parameter change strategy directly addresses the contradiction between restart speed and component protection.
2Reliability
If the rail pressure is reduced when the internal combustion engine is switched off, then the hydraulic components are less stressed, but the pressure build-up cycle is repeated excessively
Solution Approach 1:
The patent changes the pressure parameter based on the detected shutdown cause. When start-stop operation is detected, the system maintains higher rail pressure, avoiding the pressure build-up cycle. When permanent shutdown is detected, the system reduces pressure to atmospheric level. This conditional parameter adjustment protects hydraulic components from excessive stress cycles while maintaining system efficiency during frequent start-stop operations.
Solution Approach 2:
The patent implements feedback by having the control unit continuously monitor the shutdown cause and adjust pressure management accordingly. The system receives feedback about operational context (start-stop vs. permanent shutdown) and responds by adjusting the pressure control strategy. This feedback mechanism prevents unnecessary pressure cycles, protecting hydraulic components while maintaining productivity.
3Speed
If the fuel pressure is maintained at a higher first value during start-stop operation, then the engine restart is rapid, but the pressure control valve is heavily loaded
Solution Approach 1:
The patent applies dynamics by making the pressure control strategy adaptive rather than static. The control unit dynamically adjusts the rail pressure management based on the detected shutdown cause: maintaining higher pressure for start-stop operations while reducing pressure for permanent shutdowns. This dynamic adaptation resolves the contradiction by optimizing pressure levels according to the specific operational context, ensuring quick restart when needed while reducing stress during permanent shutdown.
Data Source
AI summary
An apparatus and a method are described for controlling a fuel metering system, in which the fuel pressure is controlled as a function of the operating state of the internal combustion engine. When the internal combustion engine is switched off, the fuel pressure is controlled at a first value. When a condition is present, the fuel pressure is controlled at a second value, which is normal when the internal combustion engine is switched off.