Bulk Modulus Determination in Common Rail Fuel Systems
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Solution Overview
Problem
Existing methods for determining the bulk modulus of fuels in combustion engine fuel systems are costly, degrade fuel quality, and lack reliability, with ultrasound-based methods causing wear and requiring complex, less accurate alternatives.
Innovation Solution
Measuring the pressure drop in the high pressure volume of a common rail fuel injection system using pressure sensors, with a known bulk modulus fuel to accurately determine the volume and subsequently the bulk modulus of fuels, allowing for precise control of fuel injection and adaptation to varying fuel qualities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasound sensor method is used to determine bulk modulus, then measurement capability is provided, but fuel degradation occurs and wear increases
Solution Approach 1:
The patent introduces pressure sensors as intermediary devices to measure pressure changes in the high pressure volume, which indirectly provides bulk modulus information without directly exposing the measurement system to the fuel in a way that causes degradation. The pressure sensors measure pressure drop during pump strokes, and bulk modulus is calculated from these pressure changes combined with known volume information.
Solution Approach 2:
The patent replaces the ultrasound-based acoustic measurement system with a pressure-based mechanical measurement system. Instead of using sound waves to determine bulk modulus, the system uses pressure sensors to measure pressure changes during pump strokes, eliminating the harmful acoustic effects on fuel while achieving the same measurement objective.
2Object-affected harmful factors
If alternative methods without ultrasound are used, then fuel degradation is reduced, but reliability and accuracy decrease
Solution Approach 1:
The patent implements a feedback mechanism where pressure sensor measurements during pump strokes are used to calculate bulk modulus, which then feeds back into the engine control system. This feedback loop allows the system to adapt injection parameters based on actual fuel properties, ensuring reliable operation while avoiding fuel degradation associated with ultrasound methods.
Solution Approach 2:
The system performs preliminary measurements of pressure changes during pump strokes to determine bulk modulus before using the fuel for injection. This preliminary characterization of the fuel allows the control system to optimize injection parameters in advance, ensuring reliable and accurate fuel delivery throughout operation.
3Measurement precision
If high accuracy pressure drop measurement is used, then diagnostic precision is improved, but knowledge of high pressure volume is required
Solution Approach 1:
The patent determines the high pressure volume information in advance, either through manufacturer specifications, calibration procedures, or initial measurements. This preliminary knowledge of the volume is stored and reused throughout operation, eliminating the need for complex real-time volume measurements while enabling high-accuracy pressure drop-based bulk modulus determination.
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
Enables high-accuracy determination of the bulk modulus and fuel quality, reducing wear and tear, improving reliability, and allowing for adaptive engine and vehicle operation based on actual fuel conditions.
Implementation Method 1
the high pressure pump (9) is controlled so that it supplies an amount (M) of fuel to the high pressure volume (16)
Implementation Method 2
a pressure sensor (14) measures fuel pressure in the high pressure volume (16)
Implementation Method 3
One measure of the quality of the fuel is its bulk modulus, i.e. how well the fuel compresses
Data Source
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AI summary
At a method for the determination of the bulk modulus of fuels in a fuel system of a combustion engine (2) with a common rail injection system (6), with a high pressure volume (16), comprising the high pressure side of a high pressure pump (9) and a fuel accumulator (8) with injectors (7) for injection of fuel into the cylinders of the combustion engine, first the volume of the high pressure volume is determined by way of supplying a fuel with a known bulk modulus to the fuel system and by controlling the high pressure pump (9) so that it performs a pump stroke with the volume of the high pressure volume closed. The value of said determined volume is later used with another fuel in order to determine this fuel's bulk modulus.