Engine Control Apparatus for Catalyst Temperature Rise
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Solution Overview
Problem
Internal combustion engines with lean burn operations face challenges in maintaining catalyst temperature, leading to potential drops in catalyst temperature and inefficient NOx purification due to valve overlap and fuel injection timing issues.
Innovation Solution
A control apparatus for internal combustion engines that includes a catalyst in the exhaust passage, a supercharger, in-passage and in-cylinder fuel injection valves, and a variable valve system to manage intake and exhaust valve timing, allowing fuel injection during specific engine states to retain air-fuel mixtures and optimize air-fuel ratios, thereby promoting catalyst temperature rise and NOx purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If valve overlap is created during lean burn operation to improve air-fuel mixing, then combustion efficiency is improved, but catalyst temperature drops due to low-temperature intake air flowing through exhaust passage
Solution Approach 1:
The in-passage injection valve injects fuel into the intake passage before the intake valve opens, during the valve overlap period. This preliminary fuel injection creates an air-fuel mixture that is then forced into the exhaust passage through the open intake valve, providing fuel to the catalyst before the main combustion occurs, thereby preventing catalyst temperature drop while maintaining combustion efficiency
Solution Approach 2:
The intake passage serves as an intermediary chamber where fuel is injected and mixed with intake air before being forced into the exhaust passage. This intermediary space allows the air-fuel mixture to form and then be directed to the catalyst, decoupling the fuel injection timing from the main combustion timing and enabling separate control of catalyst temperature and combustion efficiency
2Loss of energy
If fuel injection timing is retarded during supercharging to achieve stratified combustion, then fuel efficiency is improved, but catalyst temperature rise is insufficient
Solution Approach 1:
The fuel injection is segmented into two separate injections: the first injection occurs during the valve overlap period to supply fuel to the catalyst, and the second injection occurs during the intake stroke for main combustion. This segmentation allows the first injection to specifically target catalyst temperature rise while the second injection maintains fuel efficiency through stratified combustion, resolving the contradiction between the two objectives
3Speed
If valve overlap amount is increased during acceleration to improve air flow, then acceleration performance is improved, but catalyst temperature control becomes difficult during transition to steady operation
Solution Approach 1:
The system dynamically adjusts the valve overlap amount based on operating conditions. During acceleration, a large valve overlap is maintained to improve air flow and acceleration performance. During transition to steady operation, the valve overlap is reduced while the in-passage injection valve continues to provide fuel to the catalyst, ensuring catalyst temperature stability across different operating phases without compromising acceleration performance
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 effectively raises catalyst temperature and prevents misfires and NOx emission increases by adjusting fuel injection and valve overlap based on intake air pressure, ensuring efficient combustion and purification across various operating conditions.
Implementation Method 1
creating a valve overlap that is a state where the intake valve and the exhaust valve of the internal combustion engine are opened
Implementation Method 2
completing an injection of fuel from the in-passage injection valve during a period in which the intake valve is closed
Implementation Method 3
Oxygen and fuel that flow out to the exhaust passage in this manner are reacted by the catalyst having an oxidizing ability and generates heat
Implementation Method 4
the catalyst having an oxidizing ability
Implementation Method 5
when intake air pressure of the internal combustion engine is higher than atmospheric pressure
Implementation Method 6
completing an injection of fuel from the in-cylinder injection valve during an intake stroke
Data Source
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AI summary
A control apparatus of an internal combustion engine which is capable of a lean burn operation and which includes a catalyst which is provided in an exhaust passage of the internal combustion engine and which has an oxidizing ability, a supercharger; an in-passage injection valve which injects fuel into an intake passage; an in-cylinder injection valve which injects fuel into a cylinder, and a variable valve apparatus which changes at least one of an opening timing of an intake valve and a closing timing of an exhaust valve. The control apparatus performs creating a valve overlap that is a state where the intake valve and the exhaust valve of the internal combustion engine are opened, completing an injection of fuel from the in-passage injection valve during a period in which the intake valve is closed, and completing an injection of fuel from the in-cylinder injection valve during an intake stroke when intake air pressure of the internal combustion engine is higher than atmospheric pressure.