CVVD Controller Alternate Control for Hardware Failure
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Solution Overview
Problem
The CVVD system faces challenges in maintaining accurate air amount calculation and preventing engine hesitation, knocking, and start-off due to hardware failures, particularly when the actuator mechanism is damaged, leading to inconsistencies in valve position detection.
Innovation Solution
The implementation of alternate control strategies, including air amount alternate control, deviation control, and prediction control, which determine the cylinder charge amount through flow rate alternate, deviation correction, and valve duration update, respectively, to secure accurate air amounts for the combustion chamber even in hardware failure situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the hall sensing count scheme is used to detect valve position, then the valve position can be detected under normal operation, but the detection becomes inaccurate when the CVVD actuator mechanism device fails
Solution Approach 1:
The system performs preliminary detection of actuator operation status before using hall sensor data for air amount calculation. When actuator failure is detected, the system switches to alternative control strategies (default air amount, deviation-based correction, or prediction-based control) to maintain reliable operation without depending on inaccurate hall sensor readings
Solution Approach 2:
The controller acts as an intermediary that monitors both actuator status and hall sensor data. It mediates between the hall sensing count scheme and air amount calculation by introducing intermediate detection steps and alternative calculation paths when actuator failure is detected, preventing direct use of potentially inaccurate sensor data
2Productivity
If the CVVD system operates with hall sensing count, then air amount control is maintained under normal conditions, but engine hesitation and knocking occur when actuator mechanism fails
Solution Approach 1:
The system prepares alternative control strategies in advance (default air amount, deviation correction, prediction control) to cushion against the harmful effects of actuator failure. These pre-prepared alternatives prevent engine hesitation and knocking by ensuring continuous reliable air amount control even when the normal hall sensing count method becomes invalid
Solution Approach 2:
The system converts the harmful situation of actuator failure into a beneficial outcome by detecting the failure state and automatically switching to alternative control modes. This transforms what would be a harmful condition (inaccurate valve position detection leading to engine hesitation) into a manageable state where the controller can maintain stable operation through alternative calculation methods
3Reliability
If the actuator is stopped due to CAN communication disconnection, then information exchange is blocked, but the mechanism part continues moving causing valve position inconsistency
Solution Approach 1:
The system uses feedback from multiple sources (actuator status signals, hall sensor readings, and operational consistency checks) to detect when the actuator is stopped but the mechanism continues moving. This feedback mechanism allows the controller to identify the inconsistency and switch to alternative control strategies that do not rely on accurate real-time valve position feedback
Data Source
AI summary
A method for an alternate control of a continuously variable valve duration (CVVD) malfunction may include a CVVD failsafe control to resolve a calculation error of a cylinder charge amount due to a hardware failure of a CVVD system with the cylinder charge amount determined by any one of flow rate alternate, flow rate deviation correction, and valve duration update if the hardware failure is recognized by a CVVD controller, and to apply the cylinder charge amount to secure an air amount for a combustion chamber.