Engine Intake Valve Control for Catalyst Temperature Maintenance
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Solution Overview
Problem
Three-way catalytic converters in internal combustion engines face efficiency issues when the engine is stopped or torque output is reduced, leading to over-oxygenation, reduced catalyst temperature, and increased NOx production.
Innovation Solution
A controller is configured to receive a request signal to stop fuel supply, causing the intake valve to remain closed during the current and subsequent engine revolutions, and to inject fuel only after the intake valve has closed, preventing unreacted oxygen from being exhausted and maintaining catalyst efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel supply is stopped during engine stop request, then fuel consumption is reduced, but the catalytic converter becomes over-oxygenated and temperature drops below light-off temperature
Solution Approach 1:
The system performs preliminary action by injecting fuel into the cylinder before the intake valve closes during the current revolution, and before subsequent revolutions, to ensure the catalytic converter receives combustible gases and maintains its light-off temperature. This preliminary fuel injection prevents the converter from becoming over-oxygenated and dropping below operating temperature, while still allowing fuel cut during normal operation to save fuel.
Solution Approach 2:
The system applies preliminary anti-action by preventing the harmful effect of over-oxygenation before it occurs. By closing the intake valve and injecting fuel during specific revolutions after a fuel cut request, the system counteracts the tendency of the catalytic converter to become over-oxygenated and cool down, thereby maintaining its efficiency without requiring continuous fuel supply.
2Temperature
If additional fuel is injected for catalyst neutralisation, then catalyst temperature is maintained, but fuel savings are counteracted and emissions increase
Solution Approach 1:
The system applies partial action by injecting fuel only during specific revolutions (current revolution and subsequent revolutions) rather than continuously. This limited fuel injection is sufficient to prevent catalyst over-oxygenation and maintain temperature, while avoiding the excessive fuel injection that would increase emissions and negate fuel savings. The fuel injection is precisely controlled to match the minimum required for catalyst protection.
3Object-affected harmful factors
If intake valve remains closed during current and subsequent revolutions, then unreacted oxygen is prevented from exhausting, but engine torque output remains at zero
Solution Approach 1:
The system uses periodic action by alternating between fuel cut periods (when intake valve is closed) and fuel injection periods (during current and subsequent revolutions). This periodic operation allows the engine to periodically prevent oxygen from reaching the exhaust while still generating torque during fuel injection revolutions, thereby balancing catalyst protection with power delivery 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
This solution improves the efficiency of the catalytic converter during engine restarts, reduces toxic pollutants passing through the converter without conversion, and maintains catalyst temperature above the operating range.
Implementation Method 1
The catalytic converters combine oxygen with carbon monoxide and unburned hydrocarbons to produce carbon dioxide and water
Implementation Method 2
reduce oxides of nitrogen
Data Source
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AI summary
Aspects of the present invention relate to a controller (104) and method (400) for controlling operation of an internal combustion engine (101). The controller (104) is configured to: receive a first request signal indicative of a request to stop fuel being supplied to the engine (101), and cause an intake valve (301) of a cylinder (103) of the internal combustion engine (101) to remain closed during the current revolution of the internal combustion engine (101) and revolutions of the internal combustion engine (101) immediately following the current revolution of the internal combustion engine (101) in dependence on at least one of: the intake valve (301) being closed at the time of receiving the first request signal;or a next opening of the intake valve having not been scheduled. The controller (104) is also configured to cause injection of fuel into the cylinder (103) and subsequently cause the intake valve (301) to remain closed during revolutions of the internal combustion engine (101) immediately following a next closing of the intake valve (301), in dependence on at least one of: the intake valve (301) being open at the time of receiving the first request signal; and a next opening of the intake valve (301) having already been scheduled at the time of receiving the first request signal and said next opening of the intake valve (301) is to be performed.