Valve Timing Control Command Unit Unlocking Strategy
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Solution Overview
Problem
Existing valve timing control systems face issues with incomplete operation due to delayed motion of the lock pin caused by high viscosity oil at low temperatures, leading to faulty unlocking operations.
Innovation Solution
A valve timing control system with a phase adjustment unit and a lock unit that uses a control command unit to set specific command values for hydraulic fluid flow, ensuring the operation pressure exceeds the unlock pressure, and includes a confirmation stage to verify unlocking, thereby preventing faulty operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current value is set to start applying operation pressure equal to or more than the unlock pressure to the unlock oil pressure chamber, then the rotation phase can be changed, but the lock pin may experience faulty operation due to rapid rotation phase change before unlocking
Solution Approach 1:
The control command unit divides the unlocking process into two distinct stages: a first stage that gradually increases operation pressure from a low value to approach the unlock pressure, and a second stage that rapidly increases pressure to exceed the unlock pressure. This segmentation of the pressure increase process prevents sudden rotation phase changes while ensuring reliable unlocking.
Solution Approach 2:
The system performs a preliminary pressure build-up phase (first stage) before the actual unlocking action. During this preliminary stage, the operation pressure is gradually increased to near the unlock pressure level, preparing the system for unlocking while avoiding premature rotation phase changes that would cause lock pin faults.
2Speed
If the operation pressure is increased rapidly to unlock the rotation phase, then the unlocking speed is improved, but the lock pin motion delays in high viscosity oil conditions at low temperatures
Solution Approach 1:
The control command unit dynamically adjusts the pressure increase rate based on system conditions. In the first stage, pressure increases gradually to accommodate high viscosity oil conditions and allow the lock pin to move reliably. In the second stage, after the rotation phase is unlocked, pressure increases rapidly to complete the unlocking action, optimizing both reliability and speed for different phases of the process.
Solution Approach 2:
The unlocking process is divided into periodic stages with different pressure increase characteristics. The first stage uses a slower, more controlled pressure increase to ensure lock pin reliability in high viscosity conditions, while the second stage employs a faster pressure increase to achieve rapid unlocking, creating a periodic control pattern that addresses both concerns.
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
The system effectively restricts incomplete operations by ensuring the operation pressure meets the unlock pressure, even in high viscosity conditions, and quickly unlocks the rotation phase, preventing faulty operations and maintaining reliable valve timing control.
Implementation Method 1
a lock unit having a lock component between the rotors, an operation pressure being impressed from an unlock chamber to the lock component, hydraulic fluid flowing in/out the unlock chamber through the first operation chamber, the lock unit unlocking the rotation phase when the operation pressure more than or equal to the unlock pressure is impressed to the lock component
Data Source
AI summary
In a valve timing control system, a control command unit includes: a first stage setting block and a next stage setting block. The first stage setting block sets a retard holding command value as a control command value to introduce hydraulic fluid to each retard operation chamber under a state where a rotation phase is locked, to start applying an operation pressure more than or equal to an unlock pressure to a lock component. The next stage setting block sets an advance holding command value as a control command value to introduce hydraulic fluid to each advance operation chamber, after setting the retard holding command value, to maintain the applying of the operation pressure more than or equal to the unlock pressure to the lock component.