Hybrid Vehicle Discharge Power Control for No-Load Engine Operation
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Solution Overview
Problem
Hybrid vehicles face challenges in extending electric vehicle (EV) running mode and preventing driveability degradation due to insufficient power during no-load operation of the internal combustion engine, where the engine operates without providing torque output, leading to restricted discharge allowable power from the power storage device.
Innovation Solution
A control device for hybrid vehicles that includes a running mode control unit, a discharge allowable power control unit, and a determination unit, which sets discharge allowable power to a higher value when the vehicle is in charge depleting mode and the engine is stopped, allowing for load operation based on increased power when necessary, thereby preventing insufficient power situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If discharge allowable power Wout is increased when running mode is at CD mode and engine is stopped, then EV running can be extended and engine starting frequency is reduced, but when engine is at no-load operation, the discharged electric power is restricted to non-increased Wout causing insufficient actual power relative to required power
Solution Approach 1:
The patent applies dynamics by making the discharge allowable power Wout adjustable based on operating conditions. Specifically, Wout is set to a first value when the engine is stopped and a second value when the engine is operating, allowing the system to adapt power availability to the current state. This dynamic adjustment resolves the contradiction by ensuring sufficient power is available during no-load operation while still extending EV running when the engine is stopped.
Solution Approach 2:
The patent changes the parameter of discharge allowable power Wout based on the engine's operational state. When the engine is at no-load operation, Wout is set to a first value that ensures sufficient actual power is available. When the engine is stopped during CD mode, Wout can be increased to extend EV running. This parameter change strategy allows the system to optimize power availability according to specific operating conditions.
2Ease of operation
If discharge allowable power Wout is increased to suppress engine starting frequency, then EV running sense is improved, but driveability degrades when engine cannot attain load operation until required power reaches increased Wout
Solution Approach 1:
The system dynamically adjusts Wout based on whether the engine is at no-load operation or stopped. When the engine is operating (even at no-load), Wout is set to a first value that allows the engine to respond promptly to load requests, maintaining good driveability. When the engine is stopped and CD mode is active, Wout is increased to suppress unnecessary starts while preserving EV running experience.
Solution Approach 2:
The patent changes Wout based on engine operational status to balance EV running experience and engine response capability. By setting Wout to different values depending on whether the engine is running or stopped, the system improves EV running sense when appropriate while preventing driveability degradation during transitions to load operation.
3Reliability
If engine is operated in no-load operation to protect components, then discharge allowable power Wout remains non-increased, but the situation arises where discharged electric power is restricted and engine cannot attain load operation timely
Solution Approach 1:
The system uses dynamic adjustment of Wout to resolve the timing issue. When the engine is at no-load operation, Wout is set to a first value that allows timely transition to load operation, reducing the time loss. This dynamic parameter adjustment maintains component protection through controlled no-load operation while ensuring the engine can attain load operation promptly when needed.
Solution Approach 2:
The patent changes Wout based on the engine's operational state to balance component protection and response time. By adjusting Wout according to whether the engine is at no-load or stopped, the system allows timely transitions to load operation while maintaining the benefits of controlled no-load operation for component protection.
Data Source
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AI summary
A Wout control unit (154) increases a discharge allowable power (Wout) to W1 greater than W0 when the running mode is at a CD mode and an engine (ENG) is stopped. An engine operation determination unit (156) determines whether the engine (ENG) is to be set at load operation or not based on W0 when the running mode is at the CS mode, and based on W1 when the running mode is at the CD mode. In the case where the engine (ENG) is at no-load operation, the engine operation determination unit (156) determines whether the engine (ENG) is to be set at load operation or not based on W0 even if the running mode is at the CD mode.