Oil Control Valve Spool for Camshaft Phaser Reverse Flow Prevention
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Solution Overview
Problem
Existing methods for controlling oil flow in camshaft phasers of internal combustion engines, such as those in automatic stop mode, often result in reverse oil flow due to pressure imbalances, which can lead to reduced camshaft phasing performance and undesirable audible noises, especially when separate check valves are not used.
Innovation Solution
The oil control valve's spool is positioned to block oil flow between the camshaft phaser and the engine when the engine is in automatic stop mode, using a solenoid actuator to maintain all ports in a blocked state, preventing reverse flow and retaining oil within the camshaft phaser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is integrated in the oil passage to prevent reverse oil flow, then reverse oil flow is avoided, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines the check valve function with the existing oil control valve by positioning the spool to block ports when valve train efforts produce oil pressures higher than supply pressure. This merging eliminates the need for a separate check valve integration while achieving the same reverse oil flow prevention function.
Solution Approach 2:
The oil control valve spool is designed to perform multiple functions: controlling oil flow for camshaft phasing and simultaneously preventing reverse oil flow through strategic port blocking. This multi-functionality eliminates the need for additional dedicated components.
2Reliability
If a check valve is added to prevent reverse oil flow, then reverse oil flow is avoided, but manufacturing cost increases
Solution Approach 1:
The patent merges the check valve function into the existing oil control valve assembly, eliminating the need for separate check valve manufacturing and integration. This reduces part count and assembly complexity, thereby lowering manufacturing cost.
Solution Approach 2:
The oil control valve spool automatically blocks ports to prevent reverse oil flow without requiring a separate check valve component. The system uses its own existing components to achieve the protective function, eliminating additional manufacturing requirements.
3Ease of operation
If a check valve is placed far from the camshaft phaser to simplify routing, then oil routing is easier, but the check valve becomes less effective
Solution Approach 1:
The patent eliminates the distance problem by integrating the check valve function directly at the camshaft phaser location through the oil control valve spool. The spool blocks ports immediately where oil flow is controlled, ensuring maximum effectiveness without routing compromises.
4Productivity
If the spool default position provides fluid communication between camshaft phaser and oil source, then oil flow is maintained during operation, but reverse oil flow occurs when engine is stopped
Solution Approach 1:
The patent makes the spool position dynamic by using a spring-loaded mechanism that responds to pressure differentials. The spool automatically shifts to block ports when valve train efforts create higher oil pressures than supply pressure, preventing reverse flow during stop while maintaining communication during operation through normal pressure differentials.
Solution Approach 2:
The spring-loaded spool is pre-positioned to block ports in anticipation of reverse pressure conditions. When the engine stops and pressure equalizes or reverses, the spool automatically shifts to prevent reverse oil flow before it can damage the system.
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 prevents reverse oil flow and maintains a predetermined phase relationship between the crankshaft and camshaft during automatic stop mode, reducing the time needed to restore oil pressure and minimizing audible noises upon engine restart.
Implementation Method 1
using a solenoid actuator to maintain all ports in a blocked state
Implementation Method 2
positioning the spool within the spool housing to substantially block oil flow between the camshaft phaser and the internal combustion engine
Data Source
AI summary
A method for operating an oil control valve in an internal combustion engine is provided. The oil control valve controls a camshaft phaser disposed at an output side of the control valve and includes a spool disposed in a spool housing. The camshaft phaser controls the phase relationship between a crankshaft of the internal combustion engine and a camshaft of the internal combustion engine. The method includes positioning the spool within the spool housing to substantially block oil flow between the camshaft phaser and the internal combustion engine when the engine is temporarily not running.