Valve Timing Control via Preliminary Spool Positioning
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Solution Overview
Problem
Valve timing adjustment systems face challenges in releasing the phase lock mechanism due to high viscosity operating oil, leading to delayed activation and potential sticking of the lock pin, especially in low-temperature environments.
Innovation Solution
The electronic control device performs an initial control with a prescribed current value to move the spool and then a gradual change control with increasing current value to securely release the phase lock mechanism, preventing excessive hydraulic pressure and ensuring timely release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic pressure is supplied to release the phase lock mechanism, then the lock pin is released, but excessive hydraulic pressure causes the lock pin to stick due to high viscosity oil
Solution Approach 1:
The electronic control device performs preliminary action by first moving the spool to a position that supplies hydraulic pressure to the release hydraulic chamber before supplying pressure to the hydraulic chamber. This preliminary action builds up pressure gradually in the release chamber to ensure the lock pin is properly prepared for release without experiencing sudden excessive pressure that would cause sticking.
Solution Approach 2:
The hydraulic pressure supply process is segmented into two distinct stages: first supplying pressure to the release hydraulic chamber to prepare the lock pin for release, then supplying pressure to the hydraulic chamber to complete the phase adjustment. This segmentation prevents excessive pressure from being applied simultaneously, thereby preventing lock pin sticking while ensuring reliable release.
2Reliability
If gradual change control with increasing current is used, then lock pin sticking is prevented, but activation time increases
Solution Approach 1:
The electronic control device employs periodic action by using PWM control to supply current in a time-varying manner. The current is supplied at different levels at different time periods: initially at a level that moves the spool to the release chamber supply position, then adjusted to supply hydraulic pressure for lock pin release, and finally adjusted to supply pressure to the hydraulic chamber. This periodic control achieves reliable release while managing activation time efficiently.
3Productivity
If high current is applied to move the spool quickly, then activation time is reduced, but excessive hydraulic pressure is generated causing lock pin sticking
Solution Approach 1:
The system performs preliminary action by first applying current to move the spool to the position that supplies pressure to the release hydraulic chamber. This preliminary positioning of the spool ensures that when hydraulic pressure is subsequently supplied, it is directed appropriately to release the lock pin gradually, preventing excessive pressure buildup that would cause sticking while maintaining efficient activation speed.
Solution Approach 2:
The release hydraulic chamber acts as an intermediary between the hydraulic control valve and the phase adjustment mechanism. By using this intermediate chamber to build up pressure first, the system can control the pressure supply to the hydraulic chamber more effectively, preventing excessive pressure from being applied directly to the lock pin while maintaining rapid response through the spool's quick positioning.
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 allows for rapid and reliable release of the phase lock mechanism, even with high viscosity oil, reducing activation time and preventing lock pin sticking, thus improving the valve timing adjustment system's performance.
Implementation Method 1
an electromagnetic drive section that moves the spool in the shaft direction
Implementation Method 2
the fluid pressure control device supplies hydraulic pressure to the hydraulic chamber of the valve timing adjustment device
Data Source
AI summary
A valve timing adjustment system includes a valve timing adjustment device, a phase lock mechanism, a hydraulic control valve, an electromagnetic drive section, and an electronic control device. When the lock pin included in the phase lock mechanism and having the tip thereof fitted into a fitting recess is removed from the fitting recess, the electronic control device performs an initial control of applying current to the electromagnetic drive section at a prescribed current value for a prescribed time to move a spool of the hydraulic control valve from an initial position. Thereafter, the electronic control device performs a gradual change control of applying current to the electromagnetic drive section while gradually increasing the current value from a current value smaller than the current value applied in the initial control but greater than 0, to remove the lock pin from the fitting recess.