Variable Valve Timing Lock Pin for Engine Start Reliability
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Solution Overview
Problem
Existing variable valve timing control systems face issues with locking the VCT phase during engine start-up due to malfunctions, such as signal breaks or pin sticking, leading to poor engine start-up properties and potential wear or breakage from pin collisions.
Innovation Solution
A variable valve timing control apparatus that includes a lock pin, oil pressure control valve, VCT phase controller, abnormality determining portion, and valve controller, which locks the VCT phase at a predetermined phase by controlling oil pressure even if the system cannot perform feedback control, and predicts engine stalls to adjust valve timing accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is used to move VCT phase to target phase, then valve timing control precision is improved, but system reliability deteriorates when signal break or malfunction occurs
Solution Approach 1:
The lock pin is positioned in advance at a predetermined lock phase (middle position) before engine start-up. This preliminary positioning ensures that even if feedback control fails due to signal break or malfunction, the VCT phase will be in a safe middle position during start-up, preventing damage and ensuring reliable operation.
Solution Approach 2:
The lock pin acts as an intermediary mechanism that physically positions the VCT phase at a predetermined middle position. This mechanical intermediary ensures accurate phase positioning without relying on the electronic feedback control system, thereby resolving the contradiction between control precision and system reliability.
2Reliability
If lock pin is controlled to project and retreat frequently, then VCT phase locking capability is improved, but pin wear and breakage increases
Solution Approach 1:
The locking function is extracted from the feedback control system and implemented as a separate, simple mechanical lock pin mechanism. The lock pin only needs to project once to lock the VCT phase at the middle position before start-up, and remains in that position during normal operation, significantly reducing the frequency of projection and retraction cycles and thereby reducing wear and breakage risk.
3Device complexity
If VCT phase is not locked before engine stop, then system complexity is reduced, but start-up property deteriorates at next activation
Solution Approach 1:
The lock pin is positioned in advance at the middle lock phase before engine stop. This preliminary action ensures that when the engine is restarted, the VCT phase is already in the optimal middle position for start-up, preventing poor start-up properties without requiring complex real-time monitoring and adjustment systems.
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
Ensures the VCT phase is locked at a stable position before engine stop, preventing poor start-up properties and reducing wear by controlling oil pressure and adjusting valve timing to prevent engine stalls, thereby enhancing engine reliability and reducing mechanical stress.
Implementation Method 1
The oil pressure control valve controls an oil pressure that drives the variable valve timing device and the lock pin
Implementation Method 2
The lock pin locks the VCT phase at a predetermined lock phase positioned in a controllable range of the VCT phase
Data Source
AI summary
A variable valve timing control apparatus includes an abnormality determining portion and a valve controller. The abnormality determining portion determines whether there is an abnormality in a system of a VCT phase control in which an oil pressure control valve is controlled in a manner that an actual VCT phase coincides with a target phase. The valve controller controls the oil pressure control valve to drive a lock pin in a locking direction so as to lock the VCT phase when the abnormality determining portion determines that there is an abnormality in the system of the VCT phase control.