Engine Control Device Combustion Fluctuation via Angular Acceleration
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Solution Overview
Problem
Diesel engines face challenges in accurately estimating the combustion state of cylinders, leading to misfires and combustion fluctuations, especially under conditions of increased exhaust recirculation gas and varying driving conditions, which complicates engine control and increases emissions, without the ability to use combustion pressure sensors due to cost and complexity concerns.
Innovation Solution
A control device that calculates the gravity center position of total heat generation in a cylinder based on angular acceleration changes, allowing for precise control of fuel injection timing and amount to maintain optimal combustion, using angular velocity and acceleration data from a rotating shaft, without the need for additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a combustion pressure sensor is installed to grasp combustion fluctuation of each cylinder, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses angular velocity data from the existing crankshaft sensor as a copy or proxy for direct combustion pressure measurement. By calculating angular acceleration and its rate of change, the system infers combustion state without needing a dedicated combustion pressure sensor, thus achieving measurement precision improvement while avoiding the complexity and cost of installing additional sensors
Solution Approach 2:
The patent replaces the mechanical/physical combustion pressure sensor system with a computational approach using angular velocity data. The combustion state is determined through mathematical calculations (angular acceleration derivation, rate of change calculation) rather than direct mechanical pressure measurement, substituting a sensor-based system with a calculation-based system
2Object-generated harmful factors
If exhaust recirculation gas filling ratio is increased for environmental protection, then harmful emissions are reduced, but combustion stability deteriorates due to narrow fuel injection timing range
Solution Approach 1:
The patent implements a feedback control system where the combustion state is continuously monitored through angular velocity data, and fuel injection timing is adjusted based on the detected combustion fluctuation. The control unit compares the calculated combustion state with target values and corrects fuel injection timing accordingly, creating a closed-loop system that maintains combustion stability even with high exhaust recirculation gas ratios
Solution Approach 2:
The patent dynamically adjusts fuel injection timing based on real-time combustion conditions rather than using fixed timing. By continuously monitoring angular velocity changes and calculating combustion state parameters, the system adapts fuel injection timing to varying operating conditions, enabling stable combustion across different exhaust recirculation gas ratios and driving conditions
3Ease of operation
If fuel injection timing is corrected based on instantaneous angular velocity value, then combustion control is simplified, but manufacturing precision of combustion state estimation deteriorates
Solution Approach 1:
The patent performs preliminary calculations of angular acceleration and its rate of change before determining fuel injection timing corrections. By pre-processing the angular velocity data through differentiation and rate-of-change calculations, the system prepares accurate combustion state indicators that improve estimation precision while maintaining the simplicity of the overall control approach
Solution Approach 2:
The patent introduces angular acceleration and its rate of change as intermediary parameters between raw angular velocity data and fuel injection timing control. These intermediate calculations transform the simple angular velocity signal into more precise combustion state indicators, acting as mediators that enhance estimation accuracy without complicating the final control decision
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 allows for accurate control of combustion states in diesel engines, reducing misfires and combustion fluctuations, while avoiding the complexity and cost of installing combustion pressure sensors, thereby enhancing engine performance and reducing emissions.
Implementation Method 1
an angular velocity detecting unit that detects the angular velocity of a rotating shaft which is driven according to an output of an engine
Implementation Method 2
an angular acceleration calculating unit that calculates angular acceleration based on the angular velocity detected by the angular velocity detecting unit
Implementation Method 3
a heat generation timing calculating unit that calculates a certain timing when the ratio of an amount of heat generation in a cylinder to the total amount of heat generation of one cycle falls in a predetermined range, based on a change of the angular acceleration calculated by the angular acceleration calculating unit
Implementation Method 4
a combustion control unit that controls combustion in the cylinder by comparison between the certain timing calculated by the heat generation timing calculating unit and a predetermined heat generation timing reference value
Data Source
AI summary
A control device for an engine includes an angular velocity detecting unit that detects the angular velocity of a rotating shaft which is driven according to an output of an engine, an angular acceleration calculating unit that calculates angular acceleration based on the angular velocity detected by the angular velocity detecting unit, a heat generation timing calculating unit that calculates a certain timing when the ratio of an amount of heat generation in a cylinder to the total amount of heat generation of one cycle falls in a predetermined range, based on a change of the angular acceleration calculated by the angular acceleration calculating unit, and a combustion control unit that controls combustion in the cylinder by comparison between the certain timing calculated by the heat generation timing calculating unit and a predetermined heat generation timing reference value.