Variable Fuel Injection Control for Diesel Rail Pressure Stability
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Solution Overview
Problem
Diesel internal combustion engines face challenges in maintaining high fuel rail pressure during high engine speed and load conditions, leading to potential engine derating due to insufficient fuel supply, which can result in inaccurate fuel delivery and degraded performance.
Innovation Solution
The method involves reducing the total number of pilot and/or main fuel injections when a fuel rail pressure deviation is detected, adjusting injection timing and pulsewidth to maintain constant fuel rail pressure, and prioritizing pilot injections during low load conditions to mitigate noise while reducing main injections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the fuel pump size is increased to supply sufficient fuel during high fuel quantity demand, then the fuel supply capacity is improved, but parasitic loss in the pump increases
Solution Approach 1:
The patent applies dynamics by making the number of fuel injections variable rather than fixed. The control system dynamically adjusts the injection strategy based on real-time rail pressure measurements, enabling the system to adapt fuel delivery to actual demand conditions without requiring a constantly oversized pump.
Solution Approach 2:
The patent changes the parameter of injection quantity by reducing the total number of injections when rail pressure drops. This parameter change allows the system to conserve fuel in the rail, maintaining pressure without increasing pump capacity, thereby avoiding the parasitic losses associated with oversized pumps operating continuously at high capacity.
2Stability of the object's composition
If the number of fuel injections is reduced to maintain fuel rail pressure, then fuel rail pressure stability is improved, but fuel delivery quantity decreases
Solution Approach 1:
The patent implements feedback control by continuously monitoring rail pressure and using this information to adjust the injection strategy. When pressure drops below a threshold, the system responds by reducing the number of injections to conserve fuel in the rail, thereby maintaining pressure stability while still meeting fuel delivery requirements through optimized injection timing and quantity of the remaining injections.
Solution Approach 2:
The patent applies partial action by not reducing all injections uniformly, but selectively reducing the total number of injections based on pressure conditions. The control system maintains sufficient fuel delivery by optimizing the timing and quantity of the remaining injections, ensuring that critical fuel delivery needs are met while conserving enough fuel in the rail to maintain pressure stability.
3Manufacturing precision
If pilot injection timing is advanced at high engine speed/load to maintain injection interval, then injection timing control is improved, but engine performance degrades due to insufficient fuel supply
Solution Approach 1:
The patent uses feedback from rail pressure sensors to determine whether to advance pilot injection timing. When rail pressure is sufficient, the system can afford to advance timing to maintain proper intervals. When pressure drops, the feedback mechanism prevents timing advancement that would compromise fuel supply, thereby maintaining both timing control accuracy and engine performance reliability.
Solution Approach 2:
The patent makes injection timing dynamic rather than fixed. The control system adjusts pilot injection timing based on real-time rail pressure conditions, allowing timing advancement only when sufficient fuel is available in the rail. This dynamic approach maintains precise timing control while preventing performance degradation from insufficient fuel supply.
Data Source
AI summary
Methods and systems are provided for adjusting fuel injections provided to a cylinder when a fuel rail pressure deviation from a threshold pressure is detected. In one example, a method may include reducing a total number of pilot and/or main fuel injections provided to a cylinder in a given cylinder cycle in response to a reduction of pressure in a fuel rail. In this way, the threshold rail pressure may be maintained, reducing the likelihood the engine will be derated.