Piston Position Detection via In-Cylinder Pressure Sensing
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Solution Overview
Problem
Manufacturing variations, sensor degradation, and engine component wear lead to errors in compression ratio and piston position detection in internal combustion engines, affecting fuel injection timing and emissions performance in compression-ignition engines.
Innovation Solution
A method and system that use pressure sensing devices to monitor in-cylinder pressure and adjust engine crank position by determining crank angle error, allowing for accurate piston position estimation and correction, thereby improving fuel injection timing and emissions performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional crank sensor technology is used to detect piston position, then the device complexity is low, but measurement precision deteriorates due to manufacturing variations, sensor degradation, and component wear
Solution Approach 1:
The patent introduces an intermediary pressure sensing system that indirectly measures piston position through in-cylinder pressure variations. Instead of directly sensing piston position with complex mechanical sensors, the system uses pressure transducers to detect pressure changes caused by piston movement, thereby achieving accurate position detection with simpler overall system architecture
Solution Approach 2:
The patent replaces conventional mechanical crank sensor technology with a pressure-based measurement system. By substituting mechanical position sensing with pressure field measurement, the system achieves higher measurement precision while reducing mechanical complexity and improving reliability against wear and degradation
2Measurement precision
If pressure sensing devices are added to monitor in-cylinder pressure, then measurement precision of piston position improves, but device complexity increases
Solution Approach 1:
The patent makes the pressure sensing system multi-functional by using the same pressure transducers for multiple purposes: monitoring in-cylinder pressure during combustion, detecting piston position, measuring compression ratio, and identifying crank angle errors. This universal approach allows accurate measurement without proportionally increasing system complexity
Solution Approach 2:
The system uses pressure measurements to generate feedback signals that indicate crank angle errors. The pressure data is processed to create correction values that feed back into the control system, enabling continuous refinement of piston position detection without requiring additional complex sensing mechanisms
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 enables precise control of fuel injection timing, enhances emissions performance, and minimizes engine noise by accurately determining and correcting crank angle errors, leading to improved fuel economy and engine operation.
Implementation Method 1
adapting a plurality of pressure sensing devices to monitor in-cylinder pressure during ongoing operation
Data Source
AI summary
The invention comprises a method to determine a position of a piston in a cylinder of an engine during ongoing operation, comprising adapting pressure sensing devices to monitor in-cylinder pressure, and, operating the engine. In-cylinder pressure is monitored along with a corresponding engine crank position. The engine is operated in a motoring mode and in a cylinder firing mode, and a plurality of instantaneous in-cylinder pressure states are determined during compression and expansion strokes. Pressure ratios are determined based upon the instantaneous in-cylinder pressure states, which are used to determine an engine crank angle and compression ratio error and, adjust the monitored engine crank position based upon the crank angle error and readjust engine operation according to these sensed errors.