Engine Control Device for Cam Switching Torque Management
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Solution Overview
Problem
Existing control devices for internal combustion engines face challenges in reducing torque shortages and in-cylinder charge air amount differences during cam switching operations, leading to delays in engine torque follow-up and torque differences.
Innovation Solution
A control device that coordinates boost pressure control using a turbocharger and throttle valve adjustments to prevent synchronous boost pressure increases with cam switching, while maintaining in-cylinder charge air amounts by controlling the throttle valve to its closed side, ensuring consistent engine torque without decreasing turbine rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the boost pressure control device is controlled to lower boost pressure during cam switching operation, then the in-cylinder charge air amount difference is reduced, but the actual engine torque follows up delayed with respect to the required engine torque
Solution Approach 1:
The control device executes preliminary actions by controlling the throttle valve to its closed side and the boost pressure control device to maintain or increase boost pressure before and during the cam switching operation. This preliminary control prevents the in-cylinder charge air amount from decreasing, thereby avoiding torque difference while ensuring timely torque follow-up without delay.
2Speed
If the boost pressure control device increases boost pressure in response to required engine torque increase, then the engine torque follow-up is timely, but the in-cylinder charge air amount difference occurs before and after cam switching operation
Solution Approach 1:
The control device executes preliminary control actions by setting the throttle valve to its closed side and the boost pressure control device to maintain or increase boost pressure before the cam switching operation. This ensures that the in-cylinder charge air amount remains consistent before and after switching, while still allowing timely torque response through the turbocharger's inertial effect.
Solution Approach 2:
The control device changes control parameters by maintaining boost pressure control parameter at a value that does not decrease during cam switching operation. The throttle valve opening degree is controlled to its closed side, and the boost pressure control device adjusts exhaust energy recovery to maintain boost pressure, thereby preventing in-cylinder charge air amount difference while enabling timely torque response.
3Manufacturing precision
If the throttle valve is controlled to its closed side during cam switching, then the in-cylinder charge air amount is maintained, but the engine torque may become insufficient during transition
Solution Approach 1:
The control device uses the turbocharger as an intermediary to bridge the torque gap during cam switching. By maintaining or increasing boost pressure through the turbocharger's inertial effect, the system compensates for the temporary torque insufficiency that occurs when the throttle valve is closed, ensuring smooth torque transition without significant power loss.
Solution Approach 2:
The control device changes the boost pressure control parameter to maintain or increase boost pressure during cam switching operation. The throttle valve opening degree is controlled to its closed side, and the boost pressure control device adjusts exhaust energy recovery to maintain boost pressure, thereby maintaining in-cylinder charge air amount while preventing significant torque deficiency through the turbocharger's inertial effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces torque differences and transitional shortages by maintaining boost pressure and preventing turbo lag, ensuring timely engine torque follow-up and consistent performance during cam switching operations.
Implementation Method 1
a turbocharger equipped with a compressor arranged in an intake air passage
Implementation Method 2
a turbocharger equipped with a compressor arranged in an intake air passage and a turbine arranged in an exhaust gas passage
Data Source
AI summary
A control device for an internal combustion engine is configured, where a designated cam switching condition is met, to execute a boost pressure control processing and an air amount control processing. In the boost pressure control processing, the control device controls a boost pressure control device such that a boost pressure control parameter does not increase in synchronization with execution of a cam switching operation and decreases in accordance with an increase of a required engine torque after the execution of the cam switching operation. In the air amount control processing, the control device controls the opening degree of a throttle valve to its closed side in synchronization with the cam switching operation such that a difference of an in-cylinder charge air amount is not produced before and after the execution of the cam switching operation.