Fuel Injection Control Using Pressure Estimation
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Solution Overview
Problem
In fuel injection control systems without a pulsation damper, fuel pressure pulsations in low-pressure supply pipes lead to discrepancies between detected and actual fuel pressures, affecting accurate fuel injection timing and amounts.
Innovation Solution
The system estimates fuel pressure in the low-pressure supply pipe based on detected pressure inputs at predetermined intervals, using a sinusoidal wave approximation for engine speeds above a threshold to adjust fuel injection timing for the low-pressure fuel injection valve, and uses detected pressure directly for engine speeds below the threshold to ensure target fuel injection amounts are achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a pulsation damper is provided in the high-pressure pump, then fuel pressure pulsations are restrained, but device complexity increases
Solution Approach 1:
The patent extracts the pulsation damping function from a separate pulsation damper component and integrates it into the high-pressure pump structure. The pump housing itself is designed with a pulsation damping chamber that communicates with the fuel passage, allowing the pump structure to serve dual functions: fuel pressurization and pulsation damping. This eliminates the need for a separate pulsation damper component.
2Difficulty of detecting and measuring
If fuel pressure detection is performed at intervals, then measurement simplicity is maintained, but fuel injection timing accuracy deteriorates due to pressure pulsations
Solution Approach 1:
The patent performs preliminary action by detecting fuel pressure at specific predetermined timings (such as at the start of fuel injection or at predetermined crank angle positions) rather than continuously. The control unit stores these timely detected pressure values and uses them for fuel injection control calculations. This approach captures pressure data at critical moments when it is most relevant for injection timing, maintaining simplicity while improving accuracy.
Solution Approach 2:
The control unit uses the detected fuel pressure values as feedback to calculate and adjust the fuel injection timing. The detected pressure is fed back into the control algorithm to determine the appropriate injection start timing, creating a closed-loop system that adapts to actual pressure conditions rather than relying on fixed timing based on engine speed alone.
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
This approach reduces the discrepancy between actual and target fuel injection amounts by accurately controlling the low-pressure fuel injection valve, regardless of engine speed, thereby improving fuel injection precision.
Implementation Method 1
a fuel pressure sensor that detects a fuel pressure in the low-pressure supply pipe
Implementation Method 2
The low-pressure fuel injection valve is used for an engine device that is an electromagnetic valve that is opened/closed by activating/deactivating energization of a solenoid
Data Source
AI summary
When a rotational speed of an engine is higher than a predetermined rotational speed, a low-pressure fuel injection valve is controlled through the use of a fuel injection time based on an estimated fuel pressure in a low pressure supply pipe and a target fuel injection amount. When the rotational speed of the engine is equal to or lower than the predetermined rotational speed, the low-pressure fuel injection valve is controlled through the use of a fuel injection time based on a detected fuel pressure input from the fuel pressure sensor from the issuance of a command to activate energization of a solenoid to the start of energization of the solenoid and a target fuel injection amount.