Hybrid Vehicle Engine Control Device Preventing High Rotation
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Solution Overview
Problem
In hybrid vehicles with engines and rotary machines, the engine rotation speed can exceed the maximum allowed speed due to response delays from supercharging pressure, leading to high-rotation states, which existing control methods struggle to prevent effectively.
Innovation Solution
A control device that includes a high rotation curbing control unit and an engine operating point changing unit, which adjust the engine's operating point to maintain a margin speed difference and prevent excessive rotation speed by considering supercharging pressure and vehicle conditions, such as slippery roads or output limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is controlled to decrease output torque when rotation speed approaches maximum, then the rotation speed can be reduced, but the response delay of supercharging pressure causes the engine to still enter high-rotation states exceeding maximum rotation speed
Solution Approach 1:
The control device performs preliminary action by detecting when the engine rotation speed is approaching the maximum rotation speed and proactively changes the operating point to a lower rotation speed state before the engine actually exceeds the maximum speed. This anticipatory control prevents the high-rotation state from occurring in the first place, overcoming the limitation of reactive torque reduction that is delayed by supercharger response time.
Solution Approach 2:
The control device dynamically adjusts the engine operating point based on real-time rotation speed conditions. When the rotation speed difference between actual and maximum speed falls below a threshold, the system automatically transitions to a different operating state with a lower target rotation speed, creating a dynamic safety margin that adapts to changing engine conditions and prevents exceeding maximum rotation speed.
2Reliability
If the operating point is frequently changed to maintain margin speed difference, then high-rotation states are prevented, but fuel efficiency deteriorates due to excessive operating point changes
Solution Approach 1:
The control device continuously monitors the rotation speed difference between the actual engine speed and maximum speed, and uses this feedback to determine when operating point changes are necessary. By establishing a threshold-based feedback mechanism, the system only changes operating points when the margin speed difference falls below the threshold, avoiding unnecessary changes that would waste fuel while ensuring safety margins are maintained when needed.
Data Source
AI summary
When a speed difference between a maximum rotation speed and an engine rotation speed, that is, an actual rotation speed difference, is equal to or less than a margin rotation speed difference, an engine operating point is changed such that the actual rotation speed difference becomes greater than the margin rotation speed difference. Accordingly, the speed difference between the maximum rotation speed and the engine rotation speed is prevented from becoming equal to or less than the margin rotation speed difference. As a result, since a relatively sufficient margin is secured in the difference between the maximum rotation speed and the engine rotation speed, it is possible to prevent the engine rotation speed from falling into a high-rotation state in which the engine rotation speed exceeds the maximum rotation speed.