Hybrid Vehicle Control Device for Acceleration Response Delay
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Solution Overview
Problem
In hybrid vehicles with engines and rotary machines, acceleration responsiveness decreases due to a shortage of assist torque from the rotary machine when switching from EV travel mode to HV travel mode, caused by supercharging response delays in the supercharger.
Innovation Solution
A control device that includes a torque assist control unit to compensate for the output shortage of the engine by increasing the engine's rotation speed to a predetermined target speed before switching modes, with state determining and rotation speed increasing units to ensure sufficient assist torque is provided, and target rotation speed settings based on intake-pipe pressure, acceleration request level, and degree of torque shortage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is started in EV travel mode with an acceleration request, then the engine can provide drive power, but the supercharging response delay causes output shortage and decreases acceleration responsiveness
Solution Approach 1:
The control device performs preliminary action by determining the accelerator opening degree before switching from EV mode to HV mode, and pre-calculating the target engine rotation speed. This allows the engine control to be prepared in advance, reducing the response delay caused by supercharger lag and improving acceleration responsiveness.
Solution Approach 2:
The system dynamically adjusts the engine rotation speed based on the accelerator opening degree. The target rotation speed is determined as a function of the accelerator opening, allowing the engine to operate at optimal speeds for different driving conditions, thereby maximizing power output while maintaining responsiveness.
2Speed
If the rotary machine provides assist torque to compensate for engine output shortage, then acceleration responsiveness is maintained, but the assist torque may be insufficient when the rotary machine's maximum output is limited
Solution Approach 1:
The control device changes the parameter of engine rotation speed to optimize performance. By determining the target rotation speed based on the accelerator opening degree, the system ensures the engine operates in a range where it can provide sufficient power, reducing the burden on the rotary machine's assist torque capability.
3Loss of time
If the engine rotation speed is increased to a predetermined target speed before mode switching, then supercharging response delay is reduced, but energy consumption increases
Solution Approach 1:
The system optimizes the target rotation speed parameter based on the accelerator opening degree. Rather than always maximizing engine speed, the control device determines an appropriate target speed that balances response time and energy consumption, reducing unnecessary energy waste while maintaining acceptable acceleration performance.
Solution Approach 2:
The control device applies partial action by increasing engine rotation speed only to the extent necessary to reduce supercharging delay. The target rotation speed is determined as a function of accelerator opening, providing just enough pre-rotation to improve response without excessive energy consumption.
Data Source
AI summary
When a travel mode in which an engine is not used as a drive power source for travel is switched to a travel mode in which the engine is used as a drive power source for travel in response to an acceleration request from a driver, it is determined whether an assist torque which is able to be output from a second rotary machine is sufficient for a required assist torque for compensating for an output shortage of the engine due to a supercharging response delay in a supercharger. When it is determined that the assist torque is not sufficient for the required assist torque, an engine rotation speed is increased to a predetermined target rotation speed by an MG1 torque of a first rotary machine.