Exhaust Purification Device Electrostatic Capacity Detection
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Solution Overview
Problem
Existing exhaust purification systems for internal combustion engines face inefficiencies in fuel usage during forced regeneration of diesel particulate filters, as the sensitivity of pressure difference-based methods decreases in the last stage of regeneration, leading to inaccurate PM estimation and reduced fuel efficiency.
Innovation Solution
An exhaust gas purification device that includes an electrostatic capacity detecting unit to monitor the capacitance of the filter, allowing for optimized fuel supply during forced regeneration by stopping fuel injection when the rate of decrease in electrostatic capacity falls below a predetermined threshold, thereby improving fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure difference method is used to monitor PM accumulation, then the system can detect PM buildup, but the measurement precision deteriorates in the last stage of regeneration
Solution Approach 1:
The patent introduces an electrostatic capacity detection system as an intermediary method to monitor PM accumulation. Instead of relying solely on pressure difference, the system uses electrostatic capacity changes between electrodes to detect PM buildup, providing accurate measurement in the last stage of regeneration where pressure difference method fails.
Solution Approach 2:
The patent changes the detection parameter from pressure difference to electrostatic capacity. By monitoring the change in electrostatic capacity between two electrodes as PM accumulates, the system achieves reliable detection throughout the entire regeneration process, including the final stage where pressure difference sensitivity is lost.
2Reliability
If fuel supply is extended with a large safety factor, then PM removal is ensured, but fuel efficiency deteriorates
Solution Approach 1:
The patent implements a feedback control system using electrostatic capacity detection to monitor PM accumulation in real-time. The fuel supply duration is adjusted based on the actual detected PM amount rather than using a fixed safety factor, allowing the system to stop fuel supply precisely when PM removal is complete, thereby eliminating unnecessary fuel consumption.
Solution Approach 2:
The patent makes the fuel supply duration dynamic rather than fixed. Based on the electrostatic capacity measurements, the system dynamically adjusts the fuel injection amount and timing, extending fuel supply only when actually needed and reducing it when PM removal is sufficient, thus optimizing fuel efficiency while ensuring complete PM removal.
3Reliability
If the regeneration interval is reduced, then PM accumulation is controlled, but fuel efficiency deteriorates due to frequent temperature raises
Solution Approach 1:
The patent performs preliminary detection of PM accumulation using electrostatic capacity measurement before initiating regeneration. This allows the system to accurately determine when regeneration is actually needed based on detected PM levels, avoiding premature or unnecessary regeneration cycles and reducing the frequency of temperature raises.
Solution Approach 2:
The patent replaces the traditional pressure difference-based timing system with electrostatic capacity-based monitoring. This substitution enables more accurate and continuous monitoring of PM accumulation, allowing for optimized regeneration timing that reduces the frequency of unnecessary regeneration events and associated fuel consumption.
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
The system effectively reduces unnecessary fuel consumption by accurately estimating the remaining PM and optimizing fuel supply, enhancing fuel efficiency and allowing for longer regeneration intervals without fuel wastage.
Implementation Method 1
an electrostatic capacity (capacitance) detecting unit configured to detect an electrostatic capacity (capacitance) of the filter
Implementation Method 2
a filter regenerating unit configured to supply fuel to the filter to perform a forced regeneration, which burns and removes particulate matter accumulated in the filter
Data Source
AI summary
An exhaust gas purification device for an internal combustion engine, wherein an amount of fuel supply during a forced regeneration is optimized, and a fuel efficiency is effectively improved. The device includes a filter in an exhaust passage of the internal combustion engine for collecting particulate matter in an exhaust gas, an electrostatic capacity detecting unit that detects an electrostatic capacity of the filter, and a filter regenerating unit that supplies fuel to the filter and executes a forced regeneration to burn and remove the particulate matter in the filter. The filter regenerating unit stops supplying fuel when a rate of decrease in the detected electrostatic capacity per predetermined period of time reaches or falls below a predetermined lower threshold, which indicates a drop in burning efficiency of the particulate matter, while the forced regeneration is being executed.