Fuel Injection Control Device Combustion State Estimation
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Solution Overview
Problem
Existing fuel injection control systems require high accuracy from cylinder pressure sensors to estimate the combustion state of fuel injected in multiple stages, leading to increased costs due to the small changes in cylinder pressure caused by pilot injections, which are difficult to measure accurately.
Innovation Solution
A fuel injection control system that estimates the combustion state of the first injection based on the second combustion timing cylinder pressure, allowing for a larger fuel quantity to be injected, thereby increasing the change in cylinder pressure and reducing the required accuracy of the cylinder pressure sensor, and uses this estimation to control the injector operation for target heat production and injection quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pilot injection quantity is estimated based on cylinder pressure change caused by pilot combustion, then the injection quantity control accuracy is improved, but the cylinder pressure sensor accuracy requirement increases and cost increases
Solution Approach 1:
The patent uses the second combustion (main combustion) as an intermediary to indirectly estimate the first combustion state. Instead of directly measuring the small pressure change from pilot combustion, the system measures the larger pressure change from main combustion, which is influenced by the pilot combustion state, and uses this as a proxy to estimate the pilot injection quantity.
Solution Approach 2:
The patent inverts the conventional approach by not using the first combustion timing pressure to estimate the first injection quantity, but rather using the second combustion timing pressure (which shows larger changes) to estimate the first injection quantity. This reverse approach allows for lower sensor accuracy requirements.
2Measurement precision
If multiple injections are performed with small fuel quantities, then combustion control precision is improved, but the cylinder pressure sensor accuracy requirement increases
Solution Approach 1:
The patent applies the inversion principle by using the second combustion timing pressure (which exhibits larger changes due to larger fuel quantity) to estimate the first injection quantity, rather than using the first combustion timing pressure. This allows multistage injection to maintain combustion control precision while reducing sensor accuracy requirements.
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 reduces the accuracy requirements of the cylinder pressure sensor by leveraging the larger changes in cylinder pressure during the second injection, improving estimation accuracy and reducing costs while maintaining effective combustion control.
Implementation Method 1
combustion of the fuel injected by the pilot injection (referred to as pilot combustion hereinafter) occurs before combustion of the fuel injected by the main injection (referred to as main combustion hereinafter)
Data Source
AI summary
A fuel injection control device controls an operation of an injector such that fuel to be injected into a combustion chamber per combustion cycle is divided and injected at least through a first injection and a second injection, which is performed with a larger fuel quantity than the first injection after the first injection. The fuel injection control device includes an acquiring section and a first combustion state estimating section. The acquiring section acquires a sensing value of cylinder pressure in the combustion chamber sensed with a cylinder pressure sensor. The first combustion state estimating section estimates an actual combustion state of the fuel injected by the first injection based upon a second combustion timing cylinder pressure sensing value attributable to combustion of the fuel injected by the second injection out of the cylinder pressure sensing values.