Hybrid Engine Stop Control With Threshold-Based Speed Increase
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Solution Overview
Problem
Existing systems for controlling the rotation speed of internal combustion engines in hybrid vehicles can cause a sense of incongruity due to changes in vibration and operation noise when the engine is stopped, particularly when the rotation speed is low, leading to an unpleasant experience for the driver.
Innovation Solution
An electric system that includes a controller to manage the rotation speed of the internal combustion engine by performing rotation-speed increasing control only when the engine's rotation speed is above a specified threshold, thereby preventing unnecessary increases in low-speed scenarios and ensuring a smoother stop operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rotation-speed increasing control is performed during engine stop operation, then the engine rotation speed increases temporarily, but this causes sense of incongruity due to vibration and noise changes when the rotation speed is low
Solution Approach 1:
The control device changes the parameter of rotation speed threshold to determine whether to perform rotation-speed increasing control. By comparing the current rotation speed with a predetermined threshold value, the system selectively applies speed increase only when beneficial, avoiding the sense of incongruity that occurs when increasing speed from low rotation states.
2Productivity
If the engine rotation speed is increased during stop operation, then the stop control effectiveness is improved, but unnecessary torque adjustments occur when rotation speed is already low
Solution Approach 1:
Instead of always performing rotation-speed increasing control during engine stop operation, the system applies partial action by selectively activating this control only when the rotation speed exceeds a predetermined threshold. This avoids excessive energy consumption from unnecessary torque adjustments while maintaining stop control effectiveness when needed.
3Device complexity
If stop control is implemented without rotation speed threshold check, then the control process is simple, but the driver experiences sense of incongruity from vibration and noise changes
Solution Approach 1:
The control device performs a preliminary check by comparing the current rotation speed with a predetermined threshold before implementing stop control. This preliminary action prevents the sense of incongruity by avoiding rotation-speed increasing control when the engine is already at low speed, while adding minimal complexity to the control process.
Data Source
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AI summary
Provided is a method for controlling an electric device including an internal combustion engine and a motor that drives the internal combustion engine, including: a step (S4) of comparing the rotation speed of the internal combustion engine at the time when it has been determined that the internal combustion engine is to transition to a rotation stop state with a specified threshold; and a step (S5) of performing rotation-speed increasing control for making the rotation speed of the internal combustion engine temporarily higher than the rotation speed at the time of the determination, in a case where the rotation speed of the internal combustion engine at the time of the determination is higher than the threshold, in which in a case where the rotation speed of the internal combustion engine at the time of the determination is not higher than the threshold, the rotation speed of the internal combustion engine is not made higher than the rotation speed at the time of the determination but is let to decrease to stop the internal combustion engine.