Hybrid Vehicle Engine Start Torque Compensation
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Solution Overview
Problem
Hybrid vehicles face challenges in reducing starting shock due to insufficient torque margin for the rotary machine to compensate for engine start-up torque drops, leading to inadequate reduction of starting shock.
Innovation Solution
An electronic control device manages the engine start process by adjusting the starting-time inertia torque, rotation speed change rate, and torque margin, using ignition starting and clutch control to minimize starting shock when the torque margin is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotary machine outputs a starting-time compensation torque in addition to running torque during engine starting, then the starting shock is reduced, but the torque margin becomes insufficient when the running torque is already high
Solution Approach 1:
The control device changes the engine starting parameters (rotation speed change rate) based on the torque margin status. When torque margin is small, the engine rotation speed change rate is reduced to lower the starting-time inertia torque, allowing the rotary machine to provide compensation torque without exceeding its capacity
Solution Approach 2:
The system dynamically adjusts the engine starting strategy based on real-time torque margin conditions. The rotation speed change rate is made variable rather than fixed, allowing optimization of the balance between compensation torque requirement and available torque margin
2Object-affected harmful factors
If the engine rotation speed change rate is reduced to make the starting-time inertia torque smaller, then the starting shock is reduced, but the engine starting time is prolonged
Solution Approach 1:
The rotation speed change rate is dynamically adjusted based on torque margin conditions rather than being fixed. This allows the system to optimize between starting time and starting shock reduction by adapting the change rate to available torque resources
Solution Approach 2:
The engine starting parameters are changed based on torque margin status. When torque margin is sufficient, normal starting speed is used; when torque margin is small, the rotation speed change rate is reduced to enable shock reduction while accepting longer starting time
Data Source
AI summary
A hybrid vehicle with an engine and a rotary machine each coupled to a drive wheel in a power transmittable manner, comprises: an electronic control device that makes the rotary machine output a starting-time compensation torque to compensate a drop in a drive torque caused in a starting process of the engine in addition to a running torque when the engine is started while the vehicle is in a running state in which the drive torque is generated by the rotary machine and the engine is in a stopped state. The electronic control device starts the engine such that a starting-time inertia torque that is generated according to starting of the engine and causes the drop in the drive torque is made smaller when a torque margin of the rotary machine which is applied to the starting-time compensation torque is relatively small than when the torque margin is relatively large.