Hybrid EV Engine Control Using Non-WOT Torque Blending
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Solution Overview
Problem
Conventional control systems for hybrid electric vehicles prioritize power over fuel efficiency when a great driving force is requested, leading to deteriorated fuel efficiency and exhaust emission.
Innovation Solution
A control device that selectively sets between a first control mode and a second control mode, prohibiting the use of the wide-open-throttle operation line in the first control mode and setting the requested driving force based on compounded torque from non-wide-open-throttle operation lines, such as the fuel efficiency priority operation line or intermediate operation line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the wide-open-throttle operation line is used to prioritize power output when great driving force is requested, then the power performance is improved, but the fuel efficiency and exhaust emission deteriorate
Solution Approach 1:
The patent applies dynamics by making the operation line selectable rather than fixed. The control device dynamically switches between wide-open-throttle operation line (for power priority) and non-wide-open-throttle operation line (for fuel efficiency priority) based on real-time driving conditions and battery state, allowing the system to adapt its characteristics to current needs rather than being constrained to a single static operation mode
Solution Approach 2:
The patent changes the operational parameters of the engine by selecting different operation lines. When fuel efficiency is prioritized, the system selects non-wide-open-throttle operation lines that operate at lower throttle openings and optimized fuel injection parameters. When power is prioritized, the wide-open-throttle operation line is selected with parameters optimized for maximum power output, thus changing operational parameters to resolve the contradiction
2Force
If the wide-open-throttle operation line is used for great driving force requests, then the driving force output is improved, but the exhaust emission deteriorates
Solution Approach 1:
The system dynamically adjusts the operation line selection based on whether power or fuel efficiency is prioritized. When fuel efficiency priority is selected, non-wide-open-throttle operation lines are used which inherently produce lower exhaust emissions due to more complete combustion and optimized air-fuel ratios, thus dynamically reducing harmful emissions when high power is not critically needed
Solution Approach 2:
The patent changes engine operational parameters including throttle opening degree, fuel injection quantity, and ignition timing when selecting non-wide-open-throttle operation lines. These parameter changes result in more efficient combustion processes that reduce harmful exhaust emissions while still providing adequate driving force for normal driving conditions
3Power
If the control mode consumes battery electric power (CD mode), then the motor output is improved, but the battery charge depletes
Solution Approach 1:
The control device dynamically switches between CD mode (charge depleting) and CS mode (charge sustaining) based on battery state of charge and driving conditions. When battery charge is sufficient, CD mode is used to maximize motor output and improve fuel efficiency. When battery charge becomes low, the system transitions to CS mode to maintain battery charge levels, thus dynamically managing battery consumption to resolve the contradiction between motor output and battery charge depletion
Data Source
AI summary
An engine is controlled based on a wide-open-throttle operation line connecting a driving point at which the engine outputs the maximum torque in a state where the throttle valve opening degree is maximum, and a non-wide-open-throttle operation line connecting a driving point at which the exhaust state of the engine is improved as compared with the wide-open-throttle operation line. A CD mode or a CS mode is selected to drive hybrid electric vehicle. When CD mode is selected, the use of the wide-open-throttle operation line is prohibited, and a requested driving force corresponding to the state where the throttle valve opening degree is maximum is set based on a compounded torque obtained by summing an engine torque determined based on the non-wide-open-throttle operation line and a motor torque that can be output in accordance with the allowable discharge electric power of the battery, and the driving force is controlled.