Hybrid Vehicle Engine Valve Control for Catalyst Poisoning
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Solution Overview
Problem
Conventional control apparatuses for hybrid vehicles with internal combustion engines and catalysts face the issue of 'rich poisoning' during fuel-cut operations, where the catalyst is deprived of oxygen, leading to deterioration and reduced efficiency.
Innovation Solution
A control apparatus that includes a motor to drive the internal combustion engine's output shaft during fuel-cut operations, estimating the catalyst's poisoning state and controlling valve stop mechanisms to either stop or allow airflow based on this state, ensuring oxygen supply to prevent catalyst deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve stop mechanism is actuated during fuel-cut operation to suppress air supply to the catalyst, then catalyst deterioration is prevented, but rich poisoning of the catalyst occurs due to continuous oxygen deprivation
Solution Approach 1:
The control apparatus periodically alternates between valve stopping and valve opening operations during fuel-cut periods. The ECU controls the valve stop mechanism to stop valves for a first period, then open them for a second period, creating a periodic cycle. This periodic action allows the catalyst to receive oxygen intermittently, preventing rich poisoning while still providing protection during valve-stopped phases.
Solution Approach 2:
The system dynamically adjusts valve operation based on real-time catalyst state assessment. The ECU determines whether to stop or open valves by evaluating operating conditions including engine speed, load, and catalyst temperature. This dynamic control allows the system to adapt valve stopping duration and frequency to current conditions, optimizing both catalyst protection and prevention of rich poisoning.
2Loss of energy
If the internal combustion engine is stopped during fuel-cut operation to reduce fuel consumption, then fuel efficiency is improved, but the catalyst cannot receive sufficient oxygen supply
Solution Approach 1:
The valve stop mechanism serves as an intermediary control element between the engine operation and catalyst oxygen supply. By controlling valve timing and duration, the system mediates the conflict between engine stopping (for fuel savings) and catalyst oxygen needs. The valves act as a controllable barrier that can be opened to allow oxygen reach the catalyst even when the engine is otherwise stopped or in fuel-cut mode.
Solution Approach 2:
The system changes the operational parameters of the valve stop mechanism based on catalyst needs. The ECU adjusts valve stopping duration, opening timing, and frequency as control parameters to optimize oxygen supply to the catalyst during engine stop periods. By dynamically modifying these parameters, the system ensures sufficient oxygen reaches the catalyst while maintaining fuel efficiency benefits of engine stopping.
3Reliability
If the valve stop mechanism is continuously activated during fuel-cut operation to protect the catalyst, then catalyst deterioration is suppressed, but the catalyst temperature decreases and rich poisoning becomes more likely
Solution Approach 1:
The periodic alternation between valve stopping and valve opening creates thermal cycles that prevent catalyst temperature from dropping too low. During valve-opening phases, fresh air and exhaust gases flow through the catalyst, providing thermal energy that maintains catalyst temperature. This periodic thermal input prevents the catalyst from cooling down excessively while still allowing protection during valve-stopped phases.
Solution Approach 2:
The system ensures continuous useful action by periodically opening valves to maintain catalyst temperature and functionality. Even though valves are stopped for protection during fuel-cut periods, the periodic opening ensures that the catalyst remains thermally active and functional. This continuous intermittent action prevents the catalyst from entering a low-temperature state that would predispose it to rich poisoning.
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 effectively prevents catalyst deterioration by dynamically controlling valve operations, allowing oxygen supply when necessary, thereby improving exhaust emissions and reducing fuel consumption while minimizing electric power usage.
Implementation Method 1
a motor that is an electric motor that, together with the internal combustion engine, constitutes a power source of the vehicle, and that is capable of driving an output shaft of the internal combustion engine that is in a stopped state
Implementation Method 2
a catalyst that purifies exhaust gas
Implementation Method 3
a configuration is adopted that actuates the valve stop mechanism during a fuel-cut operation, and maintains at least one valve among an intake valve and an exhaust valve in a closed state
Data Source
AI summary
An engine includes variable valve mechanisms capable of causing an intake valve and an exhaust valve to stop. An ECU estimates poisoning states of catalysts, and executes and prohibits stopping of the valves based on the poisoning states. When stopping of the valves is prohibited during a fuel-cut operation, the ECU drives a crankshaft of the engine by means of a motor to idle the engine. Thus, even in a hybrid vehicle in which the engine is stopped during a fuel-cut operation, a sufficient amount of oxygen can be rapidly supplied to the catalysts by utilizing a pumping action of pistons, and the catalysts can be caused to recover from rich poisoning efficiently.