DPF Failure Detection Using Electrical Capacitance PM Sensor
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Solution Overview
Problem
Conventional DPF failure detection methods, particularly those using differential pressure sensors, face accuracy issues and are costly, bulky, and require high voltage, making them unsuitable for vehicle installation and compliance with tightening regulations.
Innovation Solution
A DPF failure detection method utilizing an electrical capacitance type PM sensor with two electrodes in the DPF to calculate and compare theoretical and actual PM deposition amounts, determining failure when divergence exceeds a limit, allowing for a simple and cost-effective detection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential pressure sensor is used to detect DPF failure, then the detection system can be implemented, but the detection accuracy is insufficient and cannot meet tightening regulatory requirements
Solution Approach 1:
The patent replaces the mechanical differential pressure sensor with an electrical capacitance-based PM sensor. This substitution enables direct measurement of particulate matter deposition on the DPF, providing significantly higher detection accuracy and reliability that meets tightening regulatory requirements while avoiding the limitations of pressure-based indirect measurement methods.
2Measurement precision
If a fixed PM sensor for research and development is used, then PM detection capability is achieved, but the device becomes massive in size, weighty, and expensive for vehicle installation
Solution Approach 1:
The patent extracts only the essential PM detection function from complex research-grade PM sensors, implementing a simplified electrical capacitance-based sensor that uses two electrodes and basic electronic components. This extraction maintains adequate PM detection capability while dramatically reducing device size, weight, and cost for practical vehicle installation.
Solution Approach 2:
The patent employs a cost-effective electrical capacitance sensor design that uses inexpensive electrodes and simple electronic circuitry, replacing expensive fixed PM sensors. This approach achieves the necessary detection function at a price point suitable for mass vehicle production and installation.
3Measurement precision
If high voltage PM sensors are used, then PM detection is achieved, but safety measures for electrical insulation are required, causing cost increase
Solution Approach 1:
The patent changes the operating voltage parameter from high voltage (2000-7000V) to low voltage operation. This parameter change maintains PM detection capability through electrical capacitance measurement while eliminating the need for complex safety measures and electrical insulation, thereby reducing device complexity and cost.
4Measurement precision
If high voltage PM sensors are used, then PM detection is achieved, but radiation noise is caused, requiring countermeasures
Solution Approach 1:
The patent changes the operating voltage parameter from high voltage to low voltage operation, which eliminates radiation noise generation. This parameter change maintains adequate PM detection capability through electrical capacitance measurement while removing the harmful radiation effect and associated countermeasure 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
Enables accurate and cost-effective DPF failure detection without the need for high voltage, reducing size, weight, and eliminating the need for safety measures and radiation noise countermeasures, thus meeting regulatory requirements.
Implementation Method 1
measuring a deposited amount (referred to as 'actual deposited amount' hereinafter) of the PM on the DPF based on an electrical capacitance of an electrical capacitance type PM sensor configured by two electrodes disposed in the DPF
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The present invention provides a DPF failure detection method and a DPF failure detection device, which can be realized with a simple configuration and detect a failure at low cost. The theoretical deposited amount of PM on a DPF 4 is calculated from the operating state of an internal combustion engine 2. The actual deposited amount of the PM on the DPF 4 is measured based on the electrical capacitance of an electrical capacitance type PM sensor 6. When the divergence of the actual deposited amount from the theoretical deposited amount exceeds an allowable limit, it is determined that the DPF 4 has a failure.