Direct-Injection Engine Fuel Quantity Adaptation via Pressure Gradient
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Solution Overview
Problem
Direct-injection internal combustion engines face inaccuracies in fuel injection during starting phases due to changes in fuel type or quality, leading to longer starting times or failure, especially when the fuel in the tank has changed since the last driving occasion.
Innovation Solution
A method that measures the pressure gradient of a high-pressure fuel injection pump at specific compression top dead centers and compares it to predefined bijective tables in the engine control unit to accurately adjust the fuel quantity injected during starting, regardless of fuel type or temperature, ensuring correct fuel injection before reaching steady operating speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the quantity of fuel injected during starting is based on previous fuel data, then the engine can start under normal conditions, but starting fails or takes longer when fuel type changes
Solution Approach 1:
The patent replaces the mechanical/memory-based fuel type tracking system with a physics-based pressure gradient measurement system. Instead of relying on stored data about previous fuel types, the system directly measures the physical properties of the current fuel through pressure gradient detection during pump operation, enabling automatic adaptation to any fuel type without prior knowledge.
Solution Approach 2:
The patent changes the parameter used for fuel characterization from categorical data (fuel type labels stored in memory) to a continuous physical parameter (pressure gradient dp/dα). This allows the system to adapt to any fuel type by measuring its actual physical behavior under compression, rather than relying on pre-programmed knowledge of specific fuel types.
2Reliability
If fuel injection quantity is increased to ensure starting, then starting reliability improves, but starting time increases due to inefficiency
Solution Approach 1:
The patent implements a feedback mechanism where the measured pressure gradient from the fuel pump is used to determine the optimal fuel injection quantity. The system measures the actual fuel compression characteristics and adjusts the injection quantity accordingly, providing real-time feedback control that optimizes starting performance while minimizing unnecessary fuel injection and time loss.
3Measurement precision
If pressure measurements are taken at multiple top dead centers, then fuel characterization accuracy improves, but measurement complexity increases
Solution Approach 1:
The patent makes the existing fuel pump serve multiple functions: it continues to perform its primary role of delivering fuel to the injection system while simultaneously acting as a measurement device for characterizing fuel properties. By measuring pressure at top dead centers during the pump's normal operation, the system obtains fuel characterization data without adding dedicated measurement hardware, thus improving accuracy while minimizing complexity increase.
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 method significantly accelerates the starting phase of direct-injection engines by accurately adjusting fuel quantity based on pressure gradients, disregarding starter speed variations and temperature, thus ensuring reliable engine startup across different fuel types and temperatures.
Implementation Method 1
Rotating the high-pressure injection pump by means of a starter, Measuring the pressure of the fuel delivered by said high-pressure injection pump, taken at least at two successive compression top dead centers of the pump operating in maximum output mode
Data Source
AI summary
A method for starting a direct-injection internal combustion engine of a vehicle includes: rotating the high-pressure injection pump by a starter; measuring fuel pressure delivered by the pump, taken at two successive compression top dead centers of the pump operating in maximum output mode; establishing the pressure gradient of the fuel, on an angular reference system, based on the two successive pressure measurements; comparing the established gradient with a predefined bijective table that respectively matches a plurality of quantities of fuel to be injected and a plurality of pressure gradients; and adapting the quantity of fuel injected during the starting phase before the engine reaches steady operating speed, depending on the result of the comparison, in order to inject a quantity of fuel that corresponds, in the predefined bijective table, to the established pressure gradient, upon authorization of the first injection given by the engine control unit.