Internal Combustion Engine Catalyst Warm-Up Control with Dual Air-Fuel Sensors
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Solution Overview
Problem
Existing spark ignition internal combustion engines face issues with catalyst activation during warm-up, leading to deteriorated exhaust properties due to unburned HC components adsorbing on the catalyst before it is activated.
Innovation Solution
An internal combustion engine control device that adjusts the catalyst warm-up process by setting a lower warm-up completion temperature based on the proportion of heavy components in the exhaust, using air-fuel ratio sensors to determine the appropriate temperature for catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If rich/lean control is performed to warm up the catalyst, then the catalyst temperature increases, but unburned HC components adsorb on the catalyst before activation causing exhaust property deterioration
Solution Approach 1:
The control device performs preliminary rich/lean control before catalyst activation to warm up the catalyst, then switches to lean control after activation. This preliminary action prepares the catalyst for effective operation while managing HC adsorption timing to minimize exhaust deterioration.
Solution Approach 2:
The control device dynamically switches between rich/lean control modes based on catalyst activation status. By adjusting the air-fuel ratio dynamically - using rich control during warm-up and lean control after activation - the system optimizes both catalyst temperature increase and exhaust property maintenance.
2Temperature
If rich/lean control is performed before catalyst activation, then catalyst warm-up is achieved, but the proportion of unburned HC components in exhaust increases
Solution Approach 1:
The control device implements periodic rich/lean cycles during the catalyst warm-up phase. This periodic action creates temperature fluctuations that promote catalyst activation while controlling the timing and duration of rich periods to limit unburned HC accumulation in the exhaust.
Solution Approach 2:
The control device changes the air-fuel ratio parameter from rich to lean based on catalyst activation detection. By adjusting this critical parameter at the appropriate timing, the system reduces unburned HC components in exhaust while maintaining effective catalyst warm-up.
3Reliability
If the warm-up completion temperature is set high, then catalyst activation is ensured, but the warm-up process duration increases
Solution Approach 1:
The control device uses feedback from oxygen sensors to detect catalyst activation status and adjust the warm-up completion temperature threshold accordingly. This feedback mechanism allows the system to ensure reliable catalyst activation while optimizing the warm-up duration by adjusting the temperature threshold based on real-time catalyst performance.
Solution Approach 2:
The warm-up completion temperature threshold is dynamically adjusted based on detected catalyst activation indicators. By making this parameter dynamic rather than fixed, the system achieves reliable catalyst activation while minimizing warm-up process duration through adaptive threshold setting.
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 solution allows early catalyst activation while minimizing exhaust deterioration, improving fuel efficiency and reducing the duration of the warm-up process.
Implementation Method 1
the proportion of unburned HC components in exhaust flowing into the catalytic increases. However, if the catalyst is not activated, the catalyst cannot control the exhaust
Implementation Method 2
an upstream air-fuel ratio sensor disposed upstream of the catalyst in the exhaust passage, and a downstream air-fuel ratio sensor disposed downstream of the catalyst in the exhaust passage
Data Source
AI summary
The internal combustion engine includes a fuel injection valve, a cylinder into which the fuel injected by the fuel injection valve is introduced, an exhaust passage through which the exhaust generated by the combustion of the fuel in the cylinder flows, a catalyst installed in the exhaust passage, an upstream air-fuel ratio sensor disposed upstream of the catalyst in the exhaust passage, and a downstream air-fuel ratio sensor disposed downstream of the catalyst in the exhaust passage. The processing circuit calculates a detection value difference which is a difference between detection values of the two air-fuel ratio sensors when the warm-up of the catalyst is completed. When the detection value difference is in the predetermined detection value difference range, the processing circuit lowers the warm-up completion temperature as compared with a case where the detection value difference is not in the detection value difference range.