Dual-Rail Pressure Control with Active Relief Valve
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Solution Overview
Problem
Internal combustion engines with common rail systems face operational instability and emission issues due to the lack of error protection in rail pressure sensor failures, leading to undefined states and potential critical engine conditions.
Innovation Solution
A method that independently regulates rail pressure by switching to emergency operation modes when a rail pressure sensor fails, using a mean rail pressure value to ensure continued operation and optimal emission control, with the passive pressure relief valve opening to divert fuel and maintain defined pressure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive pressure relief valve is provided as protective measure against excessive rail pressure, then the system is protected against critical pressure levels, but the rail pressure becomes dependent on injection quantity and engine speed, resulting in suboptimal emission values and reduced power output
Solution Approach 1:
An active pressure relief valve is introduced as an intermediary component between the rail pressure sensor and the rail system. This valve is controlled by the control unit based on sensor signals, allowing precise regulation of pressure relief timing and duration. The active valve enables optimal pressure management that balances protection against excessive pressure with maintenance of high power output and low emission values, unlike the passive valve that operates solely on pressure threshold.
Solution Approach 2:
The system implements feedback control by continuously monitoring rail pressure through sensors and adjusting the pressure relief valve operation accordingly. The control unit receives signals from the rail pressure sensor and actively controls the relief valve to maintain optimal pressure levels. This feedback mechanism allows the system to adapt to varying injection quantities and engine speeds, ensuring both protection and optimal performance.
2Stability of the object's composition
If independent rail pressure control is implemented on A-side and B-side, then pressure fluctuations are reduced, but the system becomes vulnerable to undefined states when rail pressure sensors fail, causing critical engine conditions
Solution Approach 1:
The system prepares for sensor failure by implementing a fallback mechanism before failure occurs. When a rail pressure sensor fails, the control unit detects the failure condition and automatically activates a default pressure relief strategy using the active pressure relief valve. This beforehand cushioning ensures that the system transitions smoothly to a safe operational mode, preventing undefined states and critical engine conditions while maintaining the stability benefits of independent pressure control.
Solution Approach 2:
The control system performs self-diagnosis and self-correction when sensor failures are detected. The control unit monitors sensor signals and automatically switches to alternative control strategies without external intervention. This self-service capability ensures continuous reliable operation by compensating for sensor failures through active pressure relief valve control, maintaining both stability and reliability.
3Manufacturing precision
If the suction throttle is controlled to regulate rail pressure, then the fuel volume delivered is determined precisely, but the system lacks error protection mechanisms, leaving it vulnerable to cable breaks and sensor failures
Solution Approach 1:
The active pressure relief valve serves as an intermediary safety mechanism that operates independently of the suction throttle control system. When sensor failures or cable breaks occur in the suction throttle control circuit, the pressure relief valve provides a backup control path that ensures safe pressure management. This intermediary component maintains reliability while the suction throttle continues to provide precise fuel volume delivery under normal conditions.
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
Ensures reliable engine operation with defined states and optimal emission values even after single or dual rail pressure sensor failures, allowing the engine to maintain high power output while reducing the risk of overheating.
Implementation Method 1
If the rail pressure exceeds a critical value, for example 2400 bar, the pressure relief valve opens. The fuel is then drained from the rail into the fuel tank via the open pressure relief valve.
Data Source
AI summary
The invention relates to a method for the open-loop control and the closed-loop control of an internal combustion engine (1) comprising an A-side and a B-side common rail system, the rail pressure (pCR(A)) of the common rail system on the A side being controlled via an A-side rail pressure control loop in a closed loop mode and the rail pressure (pCR(B)) of the common rail system on the B side being controlled via a B-side rail pressure control loop in a closed loop mode independently of each other. The invention is characterized in that once a defective A-side rail pressure sensor (8A) is detected, an A-side emergency operation mode is activated in which the A-side rail pressure (pCR(A)) is controlled in an open loop mode and the B-side rail pressure (pCR(BB)) is continued to be controlled in a closed loop mode, or once a defective B-side rail pressure sensor (8B) is detected, a B-side emergency operation mode is activated in which the B-side rail pressure (pCR(B)) is controlled in an open loop mode and the A-side rail pressure (pCR(A)) is continued to be controlled in a closed loop mode.