Variable Valve Timing Control Device Spool Positioning
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Solution Overview
Problem
Existing variable valve timing control devices for internal combustion engines face challenges in quickly filling the advancement and retardation chambers with hydraulic oil while avoiding erroneous release of the lock pin, particularly due to oil leakage issues that can occur with varying hydraulic oil viscosity.
Innovation Solution
A variable valve timing control device that includes an oil pressure adjustment valve with a spool that moves between three control regions to manage hydraulic oil flow, with a mode selection device that sets the spool position based on the viscosity of the hydraulic oil to optimize oil filling and minimize lock pin release errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the spool position is moved to a region where a large amount of hydraulic oil is supplied to quickly fill the advancement chamber and retardation chamber, then the oil filling time is reduced, but oil leakage inside the oil control valve may cause erroneous release of the lock pin
Solution Approach 1:
The patent applies dynamics by making the spool position adjustable and variable rather than fixed. The spool position is dynamically changed based on oil viscosity conditions detected by the control device. When viscosity is high, the spool is positioned to maximize oil flow to reduce filling time. When viscosity is low, the spool position is adjusted to prevent oil leakage that could cause erroneous lock pin release. This dynamic adaptation resolves the contradiction between fast filling and reliable locking.
Solution Approach 2:
The patent changes the spool position parameter based on oil viscosity conditions. The control device detects oil viscosity and accordingly adjusts the spool position within the oil control valve. This parameter change allows the system to optimize oil flow characteristics - positioning the spool for maximum flow when needed while preventing leakage paths that could cause premature lock pin release, thus resolving the technical contradiction.
2Reliability
If the spool position is adjusted to prevent oil leakage and avoid erroneous lock pin release, then reliability is improved, but the time required for oil filling increases
Solution Approach 1:
The system dynamically adjusts the spool position based on real-time oil viscosity detection. Rather than using a conservative fixed position that would always prevent leakage but slow filling, the spool position is actively optimized for each operating condition. This dynamic control allows the system to achieve both high reliability and fast filling by adapting to actual oil conditions.
Solution Approach 2:
The patent implements feedback control where the control device detects oil viscosity and uses this information to determine the appropriate spool position. This feedback mechanism ensures that the spool is positioned optimally - preventing leakage when viscosity is low while enabling fast filling when viscosity is high - thus resolving the contradiction between reliability and filling speed.
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 configuration reduces the time required for oil filling in the advancement and retardation chambers while preventing erroneous lock pin release, ensuring efficient and reliable operation of the engine.
Implementation Method 1
a valve timing adjustment device for changing a rotation phase of a camshaft with respect to a crank shaft by adjustment of inflow and outflow of hydraulic oil to and from an advancement chamber and a retardation chamber
Implementation Method 2
a lock pin that moves by adjustment of inflow and outflow of the hydraulic oil to and from an oil pressure chamber, to lock the rotation phase in an intermediate phase
Data Source
AI summary
A variable valve timing control device has, as control modes for adjusting inflow and outflow of oil with an OCV, a lock mode for moving a lock pin in a locking direction, a phase control mode for controlling a camshaft phase by a target phase in accordance with an operation state of an engine, and an oil filling mode for filling an advancement chamber and a retardation chamber with the oil in a state that the lock pin moves in the locking direction, before shifting from the lock mode to the phase control mode. When the oil filling mode has been selected, a target position of a spool is set based on viscosity of the oil, and the position of the spool is controlled so as to be the set target position.