Hybrid Vehicle Engine Standby Control With Lean Combustion
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Solution Overview
Problem
In hybrid vehicles, the internal combustion engine's standby operation during high battery state of charge (SOC) leads to unstable combustion and overcharging, as reducing engine load or speed affects stoichiometric combustion and exhaust performance.
Innovation Solution
Implementing a lean combustion operation at a first operating point with higher intake pressure than a predetermined threshold, lower than the charging operating point, to ensure combustion stability and prevent overcharging, while assisting electric power supply to the motor during acceleration requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal combustion engine operates at reduced power output during standby operation to prevent battery overcharging, then battery overcharging is prevented, but combustion stability deteriorates and exhaust performance is adversely affected
Solution Approach 1:
The patent changes the combustion mode parameter from stoichiometric combustion to lean combustion, and adjusts the operating point parameters (engine load and engine speed) to a specific region where lean combustion can maintain stability. This allows the engine to operate at reduced power output while maintaining combustion stability through the specific combination of lean air-fuel ratio and optimized operating conditions.
2Reliability
If the internal combustion engine reduces engine load or engine speed during standby operation, then battery overcharging is prevented, but in-cylinder gas flow motion is adversely affected
Solution Approach 1:
The patent identifies a specific operating region characterized by particular engine load and engine speed ranges where lean combustion can be performed effectively. By constraining the operating point within this identified region, the patent maintains favorable in-cylinder gas flow motion while operating at reduced power output, thus preventing battery overcharging without adversely affecting combustion stability.
3Speed
If the internal combustion engine performs standby operation with lower engine power output, then acceleration responsiveness is enhanced, but combustion stability and exhaust performance deteriorate
Solution Approach 1:
The patent transitions from stoichiometric combustion to lean combustion and optimizes the operating point parameters to enable stable operation at lower engine power output. This parameter optimization allows the engine to maintain combustion stability and exhaust performance even when operating at reduced power levels during standby operation, thereby enhancing acceleration responsiveness.
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 approach enhances acceleration responsiveness, maintains combustion stability, and prevents battery overcharging by adjusting the internal combustion engine's operating point based on SOC, ensuring efficient power delivery and reduced noise and vibration.
Implementation Method 1
the standby operation is implemented by performing a lean combustion operation at a first operating point that is lower in engine power output than a second operating point set for charging the battery
Data Source
AI summary
In the present invention, an internal combustion engine (7) drives a generator (6). The internal combustion engine (7) carries out a standby operation. The standby operation is an operation involving assisting power supply to a drive motor (2). During the standby operation of the internal combustion engine (7), the SoC of a battery (4) is equal to or higher than a predetermined SoC threshold. The operating point of the internal combustion engine (7) during the standby operation is further on a lower-output side than the operating point of the same during the charging of the battery (4). The operating point of the internal combustion engine (7) during the standby operation is an operating point in which the collector pressure of the internal combustion engine (7) is equal to or higher than a predetermined collector pressure threshold. The operating point of the internal combustion engine (7) during the standby operation is within a lean combustion region.