Hybrid Vehicle Controller Level Crossing Torque
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Solution Overview
Problem
Hybrid vehicles face difficulties in transitioning from HEV mode to EV mode, particularly when encountering level differences, as the transmission ratio remains unchanged, leading to insufficient torque delivery to the drive wheel, especially if the transmission ratio is maintained on the high side during the switch, resulting in reduced engine torque and difficulty in traversing obstacles.
Innovation Solution
The hybrid vehicle control device restarts the engine and downshifts the continuously variable transmission to a predetermined ratio capable of overcoming level differences when a level difference is detected, ensuring sufficient torque is delivered to the drive wheel by maintaining the clutch in a released state and using engine torque, even if motor torque is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transmission ratio is maintained on the high side during switching from HEV mode to EV mode, then energy efficiency is improved by reducing friction, but torque delivery capability deteriorates when encountering level differences
Solution Approach 1:
The transmission ratio is made dynamically adjustable based on driving conditions. The control device monitors vehicle state and automatically adjusts the transmission ratio to appropriate levels, enabling the system to transition between high-efficiency states and high-torque states as needed, resolving the contradiction between maintaining high transmission ratio for energy efficiency and lowering it for torque delivery capability
Solution Approach 2:
The transmission ratio parameter is changed from a fixed high value to a dynamically adjusted value based on detected driving conditions. When level differences are detected or high torque is needed, the control device lowers the transmission ratio to increase torque delivery, while maintaining high ratio during normal conditions for energy efficiency
2Loss of energy
If the clutch is released to enable EV mode operation, then energy efficiency is improved by disconnecting the engine, but adaptability deteriorates when additional torque is needed to overcome obstacles
Solution Approach 1:
The clutch engagement state is made dynamic rather than fixed. The control device can automatically engage the clutch when level differences are detected or when torque requirements exceed motor capabilities, allowing seamless transition between EV mode (clutch released) and HEV mode (clutch engaged) based on real-time driving conditions
Solution Approach 2:
The clutch mechanism serves dual functions: enabling EV mode operation by disconnecting the engine for energy efficiency, and enabling HEV mode operation by connecting the engine for additional torque. The control device manages this multi-functionality by automatically selecting the appropriate engagement state based on driving conditions
Data Source
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AI summary
In the hybrid vehicle control device according to the present invention, when it is determined that a level difference is present during travel due to the drive force of the motor with the clutch released and the engine stopped, the engine is restarted while the released state of the clutch is maintained, and the continuously variable transmission is downshifted to a predetermined transmission ratio that is capable of passing over the level difference.