Engine Control Device for Torque Stability Under Fuel Pressure Errors
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining efficient operation and low pollutant emissions under stringent legal requirements, particularly due to errors in fuel supply facilities that cause significant pressure drops in high-pressure fuel systems, leading to reduced torque and driveability issues.
Innovation Solution
A method and device for controlling internal combustion engines that determine the maximum fuel mass that can be metered into the cylinder based on the cylinder segment period and fuel pressure, adjusting air mass flow to ensure maximum torque production and minimize residual gas levels, thereby maintaining consistent torque even with fuel pressure errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fuel is supplied at very high pressure (several hundred bar) to enable fine atomization and short injection time, then fuel metering precision and combustion efficiency are improved, but the system becomes highly sensitive to pressure drops caused by errors in the fuel supply facility, leading to significant torque reduction
Solution Approach 1:
The control device determines the maximum fuel mass that can be metered in advance based on the cylinder segment period and fuel pressure before the injection cycle begins. This preliminary determination allows the system to prepare appropriate compensation strategies ahead of time, preventing torque drops rather than reacting to them after they occur.
Solution Approach 2:
The system continuously monitors fuel pressure and uses this feedback to dynamically adjust the maximum fuel mass determination. When pressure drops are detected, the control device automatically reduces the maximum fuel mass to match actual supply conditions, preventing incomplete injections and maintaining reliable operation despite pressure variations.
2Reliability
If the maximum fuel mass is reduced due to fuel pressure errors, then the risk of incomplete fuel injection is reduced, but the torque production capability and drive response are significantly degraded
Solution Approach 1:
The system changes the parameter of maximum fuel mass dynamically based on actual fuel pressure conditions. By adjusting this parameter in real-time according to pressure measurements, the system ensures complete injection when pressure is sufficient while preventing incomplete injection when pressure drops, thus maintaining both reliability and optimal torque production under varying conditions.
Solution Approach 2:
The determination of maximum fuel mass is made dynamic rather than fixed. The control device continuously adapts the maximum fuel mass value based on the cylinder segment period and current fuel pressure, allowing the system to respond flexibly to changing operating conditions and maintain optimal performance across different pressure scenarios.
3Manufacturing precision
If the air mass flow is increased to compensate for fuel pressure drops, then the air-fuel ratio can be maintained, but the residual gas level increases and combustion efficiency decreases
Solution Approach 1:
The system changes the air mass flow parameter based on the determined maximum fuel mass and required air-fuel ratio. By dynamically adjusting air mass flow to match actual fuel injection conditions, the system maintains precise air-fuel ratio control without unnecessarily increasing air flow that would raise residual gas levels and reduce combustion efficiency.
Data Source
AI summary
An internal combustion engine is provided with at least one modulator for adjusting an air mass in a cylinder. It is also provided with an injection valve for metering fuel to which fuel is supplied via a fuel supply device. A maximum fuel quantity which can be metered to the cylinder per working stroke is determined. Depending on the maximum meterable fuel quantity, a maximum producible torque is determined. An air mass flow is determined depending on an air/fuel ratio to be adjusted and the maximum meterable fuel quantity is adjusted by controlling the at least one modulator for adjusting the air mass. The injection valve is controlled in accordance with the maximum meterable fuel quantity when the required torque is greater or equal the maximum producible torque.