Catalyst Deterioration Detection via Voltage Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalyst deterioration detection systems in internal combustion engines face challenges in maintaining exhaust emission quality while detecting catalyst deterioration, as active air-fuel ratio control methods can lead to increased NOX emission and unburned gases when determining the maximum oxygen storage capacity of the catalyst.
Innovation Solution
A catalyst deterioration detection system that includes an air-fuel ratio sensor, current detection device, voltage application device, and control units to execute fuel cut and rich control strategies, allowing for precise determination of catalyst deterioration by monitoring output currents and voltage changes, thereby maintaining exhaust emission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active air-fuel ratio control is executed to calculate maximum oxygen storage amount, then catalyst deterioration can be detected, but exhaust emission deteriorates due to increased NOX and unburned gases
Solution Approach 1:
The system performs preliminary oxygen storage amount calculation using active air-fuel ratio control during a dedicated detection phase, then switches to fuel cut control for normal operation. This preliminary action allows accurate catalyst deterioration detection without continuously impacting exhaust emission quality during normal driving conditions.
Solution Approach 2:
The system periodically switches between active air-fuel ratio control mode (for detection) and fuel cut control mode (for normal operation). This periodic action enables intermittent catalyst deterioration detection while maintaining good exhaust emission quality during the majority of operating time through fuel cut control.
2Object-generated harmful factors
If fuel cut control is executed to improve exhaust emission quality, then NOX and unburned gases are reduced, but catalyst deterioration detection becomes difficult
Solution Approach 1:
The system segments operation time into two distinct phases: detection phase (active air-fuel ratio control) and operation phase (fuel cut control). This segmentation allows the system to prioritize exhaust emission quality during normal operation while reserving detection capability during dedicated phases, resolving the contradiction between emission quality and detection accuracy.
Solution Approach 2:
The system uses periodic switching between detection mode and operation mode to achieve both goals: maintaining fuel cut control for emission quality during normal operation, and periodically activating active air-fuel ratio control for accurate catalyst deterioration detection when needed.
3Measurement precision
If voltage is changed from first voltage to second voltage during rich control, then catalyst deterioration can be accurately judged, but system complexity increases
Solution Approach 1:
The system dynamically adjusts the applied voltage to the air-fuel ratio sensor based on the operational phase. During detection phase, voltage switches from first voltage to second voltage to enable accurate deterioration judgment. This dynamic voltage adjustment allows accurate measurement without requiring multiple physical sensors or complex hardware, thus limiting the increase in system complexity.
Solution Approach 2:
The system changes the voltage parameter applied to the air-fuel ratio sensor to optimize detection accuracy. By switching between first voltage and second voltage based on operational conditions, the system achieves accurate catalyst deterioration judgment using a single sensor, avoiding the need for additional sensors or complex measurement systems.
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 detects catalyst deterioration without deteriorating exhaust emission quality by accurately judging the degree of catalyst degradation through controlled air-fuel ratio adjustments and voltage changes, ensuring efficient purification performance.
Implementation Method 1
an air-fuel ratio sensor arranged at a downstream side of the catalyst and detecting an air-fuel ratio of outflowing exhaust gas flowing out from the catalyst; a current detection device detecting an output current of the air-fuel ratio sensor
Implementation Method 2
a catalyst having an oxygen storage ability is known. A catalyst having an oxygen storage ability can remove the unburned gases (HC, CO, etc.) and NOX in the exhaust gas
Implementation Method 3
a catalyst is provided for purifying the exhaust gas discharged from the internal combustion engine
Implementation Method 4
a voltage application device applying a voltage to the air-fuel ratio sensor; a voltage control part configured to control the voltage applied to the air-fuel ratio sensor via the voltage application device
Data Source
AI summary
A catalyst deterioration detection system 1 comprises an air-fuel ratio sensor 41, a current detection device 61, a voltage application device 60, a voltage control part 71, an air-fuel ratio control part 72 and a deterioration judging part 73. The air-fuel ratio control part executes fuel cut control, and, after the fuel cut control, executes rich control. The voltage control part, if judging that the air-fuel ratio of the outflowing exhaust gas has reached the stoichiometric air-fuel ratio when setting the applied voltage to a first voltage in a limit current region during the rich control, changes the applied voltage from the first voltage to a second voltage in a limit current region. The deterioration judging part judges the degree of deterioration of the catalyst based on the output current of the air-fuel ratio sensor when the applied voltage is set to the second voltage.