Diesel Engine Combustion Control via Vibration Signal Analysis
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Solution Overview
Problem
Existing methods for controlling diesel engine combustion require expensive pressure sensors installed within cylinders, increasing manufacturing costs and complicating the process.
Innovation Solution
A method that uses a vibration sensor attached to the engine block to estimate maximum pressure generation timing and ignition start timing by transforming vibration signals into frequency response functions, allowing for control of combustion timing without direct pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are directly mounted within cylinders to measure combustion pressure, then combustion control precision is improved, but manufacturing costs increase and device complexity increases
Solution Approach 1:
The patent uses vibration signals as an intermediary to indirectly measure combustion pressure characteristics. Instead of directly measuring pressure with sensors inside the cylinder, the system measures vibrations of the engine block caused by combustion pressure variations, transforming a direct pressure measurement problem into an indirect vibration measurement problem that can be solved with simpler sensors.
Solution Approach 2:
The patent replaces the mechanical pressure sensing system (pressure sensors mounted in cylinders) with a vibration sensing system. By substituting the direct mechanical pressure measurement approach with vibration-based indirect measurement, the system achieves comparable combustion control precision while eliminating the need for complex pressure sensor installation and wiring.
2Ease of operation
If pressure sensors and connecting wires are installed in cylinders, then combustion control is enabled, but manufacturing costs increase
Solution Approach 1:
The patent extracts the pressure measurement function from the combustion chamber environment by measuring vibrations of the engine block instead. This extraction eliminates the need to install expensive pressure sensors and wiring inside the cylinders, thereby reducing manufacturing costs while preserving the essential combustion control capability through alternative vibration-based measurement.
Solution Approach 2:
The patent employs relatively inexpensive vibration sensors attached to the engine block exterior instead of expensive pressure sensors that require installation inside cylinders. The vibration sensors provide sufficient data for combustion control without the high cost associated with direct pressure measurement systems, making the overall system more cost-effective for vehicle manufacturing.
3Ease of manufacture
If vibration sensors are used to estimate pressure timing, then manufacturing costs decrease, but measurement precision may be affected
Solution Approach 1:
The patent applies preliminary calibration and establishes correlation relationships between vibration signals and actual pressure timing characteristics before actual combustion control operation. By pre-processing the vibration data and establishing reference relationships, the system ensures that the vibration-based timing estimation achieves sufficient precision for practical combustion control, bridging the gap between cost-effective vibration sensing and accurate timing measurement.
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 cost-effective control of diesel engine combustion by eliminating the need for high-priced pressure sensors and improving productivity through non-contact vibration sensing, while maintaining accurate fuel injection timing and amount correction.
Implementation Method 1
measuring vibrations generated in the engine
Implementation Method 2
transforming a vibration signal set in the measurement region setting step to a frequency response function
Data Source
AI summary
A method of controlling combustion of a diesel engine may include a vibration measuring step of measuring engine vibrations, a measurement region setting step of setting a range where an LPP (location of peak pressure) is predicted from measured vibration data, a frequency transforming step of transforming a vibration signal to a frequency response function, a frequency integrating step of integrating the transformed frequency response function, an LPP detecting step of selecting a location of peak pressure from integrated frequency response function, an estimated value determining step of selecting LPP offset and SOC (start of combustion) offset by using the detected LPP, an error determining step of determining LPP value error and SOC value error by comparing the estimated LPP value and the estimated SOC value with a target LPP value and a target SOC value, and a combustion correcting step of correcting and controlling combustion by the determined errors.