Common Rail Pressure Control for Engine Foot Lifting Torque
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Solution Overview
Problem
Internal combustion engines with direct fuel injection struggle to manage torque during the foot lifting phase, leading to sudden engine decoupling and potential damage, as existing solutions do not adequately control fuel injection to match the required torque setpoint, resulting in excessive fuel flow and vibration issues.
Innovation Solution
A method is implemented to control the internal combustion engine by reducing the common injection rail pressure to an intermediate value, adjusting airflow, and increasing richness to minimize fuel flow during the initial phase of foot lifting, followed by a closed-loop richness regulation to maintain optimal torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the common rail pressure is maintained at high level during foot lifting phase, then the minimum injection quantity is sufficient for torque production, but the fuel flow exceeds the required amount causing excessive torque and engine vibration
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the common rail pressure from a high initial value to a lower intermediate value during the foot lifting phase. This pressure reduction allows the system to deliver the minimum required fuel flow for torque production without excessive fuel injection, thereby resolving the contradiction between sufficient fuel delivery and avoiding over-injection.
Solution Approach 2:
The system transitions from a static high pressure state to a dynamic pressure control strategy. The common rail pressure is actively managed through three distinct phases (reduction to intermediate value, maintenance at intermediate value, and cutoff), allowing the fuel injection system to adapt to the changing torque requirements during foot lifting, thus preventing both insufficient and excessive fuel delivery.
2Productivity
If the torque setpoint is immediately reduced to zero during foot lifting phase, then the engine braking is maximized, but the sudden engine decoupling causes risk of breakage and inconvenience to occupants
Solution Approach 1:
The patent implements preliminary action by introducing an intermediate torque setpoint phase before the final zero torque setpoint. During this intermediate phase, the common rail pressure is reduced to an intermediate value and maintained, allowing the engine to gradually decouple from the vehicle. This preliminary gradual decoupling prevents sudden shocks to the connecting elements while still achieving maximum engine braking in the final phase.
3Duration of action of moving object
If the injector opening time is set to minimum value during intermediate torque phase, then the fuel flow is minimized, but the high rail pressure still results in fuel flow greater than necessary for intermediate torque production
Solution Approach 1:
The patent resolves this contradiction by changing the rail pressure parameter from high to intermediate value during the intermediate torque phase. This pressure change, combined with the minimum injector opening time, ensures that the fuel flow quantity precisely matches the requirements for intermediate torque production, eliminating the excess fuel flow that would occur with high pressure.
Data Source
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AI summary
This method for controlling an internal combustion engine (2) associated with a common rail injection system (82) in at least one cylinder (16, 18, 20) of the engine is implemented when a driver of the vehicle releases the accelerator pedal, and comprises successive steps in which it is determined (61) that the accelerator pedal is released, an intermediate torque command is applied (63), and then a final torque command is applied (67). It comprises, successively: - a first step (63) in which the common rail injection pressure (Prail) (82) is reduced to an intermediate value, - a second step (65) in which the common rail injection pressure (Prail) (82) is maintained at the intermediate value, and - a third step (67) in which the injection in cylinders (16, 18, 20) is cut off.