Variable Valve Timing Control Abnormality Handling
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Solution Overview
Problem
When an abnormality occurs in the control command input for a variable valve timing device, the valve timing may return to a mechanical default position, leading to impaired engine operability, including reduced startability and combustion stability.
Innovation Solution
A control apparatus and method that detect input abnormalities and control the variable valve timing device to a predetermined position shifted from the mechanical default position, thereby maintaining optimal engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator driving is stopped based on control command abnormality, then the system responds to the abnormality, but the valve timing returns to mechanical default position causing engine operability to deteriorate
Solution Approach 1:
The control apparatus pre-establishes a predetermined valve timing position that is shifted from the mechanical default position. When control command abnormality is detected, the system switches to this predetermined position in advance, preventing the valve timing from returning to the mechanical default position and maintaining engine operability during abnormal conditions.
2Reliability
If the valve timing returns to mechanical default position, then the abnormality is addressed, but startability and combustion stability are impaired
Solution Approach 1:
The system pre-defines a predetermined valve timing position that maintains appropriate combustion characteristics. When abnormality occurs, this predetermined position is activated, ensuring that startability and combustion stability are preserved even during abnormal operation, rather than allowing return to the mechanical default position.
Data Source
AI summary
The present invention relates to an internal combustion engine including a VTC controller for controlling driving of a variable valve timing device and an engine control module (ECM) for calculating and transferring a valve timing control command. In the present invention, each of the VTC controller and the ECM detects whether an abnormality of a communication circuit used for transferring a control command is present or not. If the abnormality is detected, the VTC controller and the ECM set a target value for an abnormal state with the same characteristic, and perform a control operation based on the target value in the abnormal state. In this manner, a decrease in engine operability when an abnormality occurs in the communication circuit of a control command is suppressed.