Vehicle Control Device Lock-Up Timing for Vibration Suppression
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Solution Overview
Problem
Existing vehicle control systems experience large vehicle vibrations and booming noise due to the torque variation of internal combustion engines, particularly when the lock-up clutch is engaged before the compression ratio is lowered, leading to inefficient fuel economy and increased noise levels.
Innovation Solution
A control device that coordinates the switching of the lock-up mechanism of the torque converter with the variable compression ratio mechanism, ensuring the lock-up mechanism is only engaged after the compression ratio has been shifted to a low ratio, thereby reducing vehicle vibrations and noise by avoiding the lock-up ON state at high compression ratios and minimizing the step change in compression ratio during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lock-up clutch is engaged before the compression ratio is lowered, then the response of the lock-up mechanism is faster, but large vehicle vibration and booming noise are generated due to the torque variation of the internal combustion engine
Solution Approach 1:
The compression ratio is lowered in advance before the lock-up clutch is engaged. The control device switches the compression ratio from a high compression ratio to a low compression ratio before switching the lock-up mechanism from a lock-up OFF state to a lock-up ON state, ensuring that the engine torque variation is minimized before the lock-up engagement occurs.
Solution Approach 2:
The compression ratio parameter is changed from high to low before the lock-up mechanism is engaged. By adjusting the compression ratio parameter in advance, the torque variation of the internal combustion engine is reduced, thereby suppressing vehicle vibration and booming noise when the lock-up clutch engages.
2Object-generated harmful factors
If the compression ratio is lowered before the lock-up clutch is engaged, then vehicle vibration is suppressed, but fuel economy is reduced due to the delayed lock-up engagement
Solution Approach 1:
The compression ratio is lowered in advance before the lock-up clutch is engaged. The control device switches the compression ratio from a high compression ratio to a low compression ratio before switching the lock-up mechanism from a lock-up OFF state to a lock-up ON state, ensuring that the engine torque variation is minimized before the lock-up engagement occurs.
3Loss of time
If the lock-up mechanism is switched to ON state immediately, then the response time is shorter, but the step change in compression ratio increases causing more vehicle vibration
Solution Approach 1:
The compression ratio is lowered in advance before the lock-up clutch is engaged. The control device switches the compression ratio from a high compression ratio to a low compression ratio before switching the lock-up mechanism from a lock-up OFF state to a lock-up ON state, ensuring that the engine torque variation is minimized before the lock-up engagement occurs.
Data Source
AI summary
A control device for a vehicle including a variable compression ratio mechanism arranged to vary an engine compression ratio of an internal combustion engine, and a torque converter which includes a lock-up mechanism, and which is disposed between the internal combustion engine and a transmission, has a controller configured to switch the engine compression ratio from a high compression ratio to a low compression ratio, and to switch the lock-up mechanism from a lock-up OFF state to a lock-up ON state. When the controller is switching the engine compression ratio from the high compression ratio to the low compression ratio, the controller starts switching the lock-up mechanism to the lock-up ON state when a current engine compression ratio is equal to or smaller than a permissible compression ratio which is between the high compression ratio and the low compression ratio.