Hybrid Engine Start Controller Torque Optimization
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Solution Overview
Problem
In hybrid vehicles, the engine start torque from the motor fluctuates due to factors other than the engine stop crank position, leading to increased redundant power savings during motor travel, which narrows the electric vehicle (EV) travel range and affects fuel economy.
Innovation Solution
An engine start controller for hybrid vehicles that optimizes transmission torque by setting a target engine speed value based on the engine stop crank position and adjusts it using a clutch transmission torque control section, with feedback correction to minimize engine start torque and extend EV travel range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine start torque is set to reliably start the engine considering factors other than stop crank position, then the engine starting reliability is improved, but the motor travel range is narrowed due to increased redundant power savings
Solution Approach 1:
The system performs preliminary determination of the engine stop crank position before engine start, and pre-calculates the optimal motor travel range and redundant power requirements based on this position. This allows the engine start torque to be optimized in advance, ensuring reliable starting while minimizing the impact on motor travel range.
Solution Approach 2:
The system dynamically adjusts the engine start torque parameter based on the determined stop crank position and other operating conditions. By changing the torque parameter adaptively rather than using a fixed conservative value, the system achieves reliable engine starting while reducing the redundant power that would otherwise be saved during motor travel.
2Reliability
If the engine start torque is set to reliably start the engine, then the engine starting reliability is improved, but fuel economy deteriorates due to increased redundant power savings
Solution Approach 1:
The system determines the stop crank position and calculates optimal engine start torque requirements before engine start occurs. This preliminary calculation ensures that sufficient torque is available for reliable starting while minimizing unnecessary energy consumption during motor travel, thereby improving overall fuel economy.
Solution Approach 2:
The system adaptively adjusts the engine start torque parameter based on real-time conditions including stop crank position, battery state of charge, and vehicle operating conditions. This dynamic parameter optimization ensures reliable engine starting while minimizing energy loss and improving fuel economy compared to fixed conservative torque settings.
Data Source
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AI summary
A hybrid vehicle (10) has, as drive sources of the hybrid vehicle (10), an engine (20) and a motor (40) mutually coupled via a clutch (30). An engine start controller (1) for the hybrid vehicle (10) includes: a clutch transmission torque control section (61) that controls transmission torque of the clutch (30) on the basis of a predicted engine speed value at the time of starting the engine (20) using the motor (40) via the clutch (30); and a predicted engine speed value setting section (62) that sets the predicted engine speed value on the basis of a stop crank position of the engine (20).