Hybrid System Control Map for Smooth Torque Transitions
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Solution Overview
Problem
Existing hybrid vehicle control methods face delays in transitioning from motor travel to engine travel due to battery state-of-charge requirements and lack consideration for variable speed gear ratios, leading to clutch engagement shocks.
Innovation Solution
A hybrid system control method that uses a map to determine target torques based on vehicle velocity and battery state-of-charge, initiating engine startup when necessary and controlling both the engine and electric means to achieve smooth transitions, with a variable speed transmission and clutch engagement strategy to reduce shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hybrid vehicle waits for battery state-of-charge requirements to be met before transitioning from motor travel to engine travel, then the battery can maintain adequate charge levels, but the transition delay increases and response time to driver acceleration requests deteriorates
Solution Approach 1:
The control method predicts future torque requirements based on current vehicle state and driver behavior patterns, and initiates engine startup in advance when the predicted torque demand will exceed motor capability. This preliminary action ensures the engine is ready before actually needed, eliminating transition delays while maintaining battery charge levels through intelligent prediction rather than conservative waiting
2Speed
If the hybrid vehicle engages the clutch quickly to transition to engine travel, then the response time improves, but shock and vibration increase due to variable speed gear ratio mismatches
Solution Approach 1:
The system predicts future torque requirements and initiates engine startup with clutch engagement in advance, allowing the engine to reach optimal operating speed before actual torque transfer is needed. This preliminary speed synchronization eliminates shock during the actual engagement moment
Solution Approach 2:
The control method dynamically adjusts engine speed and clutch engagement timing based on predicted torque demands and current vehicle state. By changing the engine speed parameter in advance to match the required torque delivery speed, the system achieves fast engagement without shock or vibration
Data Source
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AI summary
To enable a smooth transition from motor travel to hybrid travel despite the situation-of-charge of a battery and reduce shock at the time of engagement of a clutch element. A hybrid system uses a state map 70 for deciding target torques of an engine and a motor on the basis of an accelerator stroke position, a vehicle velocity and a battery state-of-charge SOC. In the map 70, there are defined a motor maximum torque line that demarcates a motor upper limit torque that changes depending on the SOC and a motor margin torque line that is a predetermined margin lower than the motor maximum torque line. When the position on the map determined by the accelerator stroke position, the vehicle velocity and the battery state-of-charge is below the margin torque line, the hybrid system performs electric travel, and when the position on the map is on or above the margin torque line, the hybrid system initiates engine startup processing, and when the position on the map becomes a torque position exceeding the maximum torque line, the hybrid system sets target torques of the engine and the motor in order to achieve a torque corresponding to the accelerator stroke position.