Internal Combustion Engine Control Device for Catalyst Purification
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Solution Overview
Problem
The frequency of motoring operations accompanied by fuel cut and engine stop due to idling stop increases, leading to inaccurate grasping of the oxygen storage state and temperature in three-way catalysts, resulting in deteriorated catalyst purification efficiency and emission performance.
Innovation Solution
An internal combustion engine control device is implemented, featuring an exhaust purification catalyst, an air-fuel ratio sensor upstream, and an oxygen sensor downstream, with a downstream equivalence ratio calculation unit, oxygen output calculation unit, equivalence ratio correction unit, and air-fuel ratio control unit, utilizing statistical models to accurately calculate and correct the catalyst's exhaust gas equivalence ratio and control the air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If motoring operation with fuel cut and engine stop is increased to reduce fuel consumption, then fuel consumption decreases, but the oxygen storage state and temperature in the three-way catalyst cannot be accurately grasped, leading to deteriorated purification efficiency
Solution Approach 1:
The system performs preliminary rich correction of the air-fuel ratio before motoring operation to pre-charge the catalyst with oxygen storage capacity. This preliminary action ensures that when fuel cut occurs, the catalyst maintains sufficient oxygen storage state to continue purifying emissions, thus resolving the contradiction between fuel savings and catalyst performance maintenance.
Solution Approach 2:
The system uses feedback from oxygen sensors positioned both upstream and downstream of the catalyst to continuously monitor the oxygen storage state. Based on this feedback, the control device adjusts the air-fuel ratio correction in real-time, ensuring the catalyst maintains optimal purification efficiency even during frequent start-stop operations. The feedback mechanism allows the system to adapt to changing catalyst conditions while managing fuel consumption.
2Ease of operation
If feedback correction is performed based on oxygen sensor detection downstream of the catalyst, then air-fuel ratio control is adjusted, but the oxygen storage state reaches limit values when oxygen presence is detected, causing deterioration of emission performance
Solution Approach 1:
The system performs preliminary rich correction based on upstream oxygen sensor data before the catalyst oxygen storage state reaches its lower limit. This advance action prevents the catalyst from entering a state where emission performance deteriorates, while still allowing effective air-fuel ratio control through feedback mechanisms.
Solution Approach 2:
The system introduces an intermediary calculation mechanism that estimates the catalyst downstream exhaust gas equivalence ratio using statistical models. This intermediary estimation allows the control system to adjust air-fuel ratio based on predicted catalyst conditions rather than waiting for downstream oxygen sensor detection, preventing the catalyst oxygen storage state from reaching limit values while maintaining effective control.
3Adaptability or versatility
If rich correction is performed based on fuel increase period according to estimated oxygen storage amount, then air-fuel ratio is adjusted, but change in oxygen storage capacity accompanying catalyst deterioration cannot be considered, leading to inappropriate correction and deteriorated emission performance
Solution Approach 1:
The system dynamically adapts the rich correction strategy by continuously updating the statistical model parameters based on actual catalyst performance data. As the catalyst deteriorates, the model automatically adjusts to reflect changing oxygen storage capacity, ensuring appropriate air-fuel ratio correction is applied. This dynamic adaptation maintains emission performance despite catalyst aging, while preserving the versatility of air-fuel ratio adjustment.
Solution Approach 2:
The system implements a dual-feedback mechanism: upstream oxygen sensor feedback for preliminary correction and downstream oxygen sensor feedback for verification. This combined feedback system allows the control device to detect catalyst deterioration over time and adjust the rich correction strategy accordingly, ensuring emission performance is maintained while adapting to changing catalyst conditions.
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 solution maintains high catalyst purification efficiency and prevents deterioration of emission performance by accurately managing the oxygen storage state and air-fuel ratio, even during catalyst deterioration.
Implementation Method 1
an air-fuel ratio sensor disposed upstream of the exhaust purification catalyst
Implementation Method 2
an oxygen sensor disposed downstream of the exhaust purification catalyst
Implementation Method 3
the oxygen storage state and temperature in the three-way catalyst cannot be accurately grasped
Data Source
AI summary
To keep medium purification efficiency at a high level and prevent deterioration of emission performance. An aspect of the present invention includes: a downstream equivalence ratio calculation unit that calculates a catalyst downstream exhaust gas equivalence ratio by using a catalyst statistical model that receives at least a detection value of an air-fuel ratio sensor on an upstream side of a catalyst and outputs a catalyst downstream exhaust gas equivalence ratio; an oxygen output calculation unit that calculates an output value of an oxygen sensor by using an oxygen sensor statistical model that receives the catalyst downstream exhaust gas equivalence ratio and outputs an output value of the oxygen sensor on the downstream side of the catalyst; a downstream equivalence ratio correction unit that corrects the catalyst downstream exhaust gas equivalence ratio calculated by the downstream equivalence ratio calculation unit based on a calculation result of the oxygen output calculation unit and the detection value of the oxygen sensor; and an air-fuel ratio control unit that controls an air-fuel ratio of an air-fuel mixture of an internal combustion engine based on the corrected catalyst downstream exhaust gas equivalence ratio and air-fuel ratio target value.