Fuel Injection Quantity Determination via Rail Pressure Bulk Modulus
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Solution Overview
Problem
In internal combustion engines with direct injection, the precision of fuel injection is compromised when the high-pressure pump is disabled, leading to difficulties in accurately determining the quantity of fuel injected due to fuel vaporization effects influenced by pressure and temperature, which existing injector models struggle to simulate effectively.
Innovation Solution
A method involving measuring and filtering pressure in the injection rail, identifying relative pressure drops, and applying the bulk modulus to determine the equivalent quantity of fuel injected, with optional corrective terms based on pressure variations or durations, to improve precision in degraded operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is injected at low pressure due to high-pressure pump failure, then the engine can operate in degraded mode, but fuel vaporizes more easily making precise fuel quantity determination difficult
Solution Approach 1:
The patent replaces mechanical/injector-model-based fuel quantity estimation with a pressure-based measurement system. By using pressure sensors to measure pressure drops in the injection rail and applying the bulk modulus formula, the system calculates fuel quantity directly from pressure changes, eliminating the need for complex vaporization modeling and improving measurement precision in degraded mode operation.
Solution Approach 2:
The patent changes the measurement parameter from fuel quantity directly (which is difficult to measure) to pressure drop (which is easily measurable). By monitoring pressure changes in the injection rail before and after fuel injection, and using the bulk modulus to convert pressure drop to fuel quantity, the system achieves accurate fuel quantity determination despite vaporization effects.
2Adaptability or versatility
If injector models are used to account for fuel vaporization, then fuel vaporization can be considered, but the models cannot precisely adjust fuel quantity due to complex vaporization physics
Solution Approach 1:
The patent replaces complex vaporization modeling with a direct pressure measurement approach. Instead of trying to model vaporization physics to estimate fuel quantity, the system directly measures pressure drops in the injection rail and uses the bulk modulus to calculate fuel quantity, bypassing the need for vaporization models entirely and achieving precise measurements.
Solution Approach 2:
The patent introduces pressure drop as an intermediary parameter that links fuel injection quantity to measurable physical quantities. By measuring pressure changes in the injection rail and using the bulk modulus relationship, the system creates a direct and accurate pathway from pressure measurement to fuel quantity determination, avoiding the need for complex vaporization models.
3Temperature
If pressure and temperature are used to influence vaporization modeling, then vaporization can be simulated, but precise fuel quantity adjustment remains unachievable
Solution Approach 1:
The patent substitutes temperature-based vaporization modeling with pressure-based direct measurement. By measuring pressure drops in the injection rail and applying the bulk modulus formula, the system determines fuel quantity directly without needing to model temperature effects or vaporization physics, achieving precise measurements regardless of temperature variations.
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 enhances the accuracy of fuel injection quantity determination, reducing combustion misfires and improving air/fuel mix adjustment, thereby enhancing engine performance and emission control.
Implementation Method 1
determining the quantity of fuel injected by applying the bulk modulus for the two pressure drops identified as a function of the temperature in the injection rail
Implementation Method 2
Fuel vaporizes more easily. Fuel in gaseous phase is then injected with fuel in liquid phase. The proportion of fuel in gaseous phase must be taken into account
Data Source
AI summary
A method for determining a quantity of fuel injected into a cylinder of an internal combustion engine including an injection rail includes: —measuring the pressure prevailing in the injection rail during fuel injection from the rail into a cylinder; —filtering the pressure measurement; —determining the relative minimum and maximum points of the filtered pressure curve; —insofar as a first (Pdrop1) pressure drop followed by a pressure rise and then a second (Pdrop2) pressure drop is identified, determining a physical quantity that makes it possible to characterize the first pressure drop and the second pressure drop; and —determining the quantity of fuel injected by applying the bulk modulus for the two pressure drops identified as a function of the temperature in the injection rail.