Camshaft Phaser Lock Pin Shutoff Valve Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional camshaft phaser systems experience oil leakage from advance and retard chambers during engine shutdown, leading to delayed oil pressure buildup and excessive wear due to premature air pockets, causing start-up noise, vibration, and harshness issues, as well as binding of the lock pin due to rapid oil pressure application.
Innovation Solution
A camshaft phaser with a lock pin that shuts off communication between the advance and retard chambers and the front cam bearing and/or oil control valve, preventing oil leakage and ensuring oil retention, and applying oil pressure only after the lock pin is unlocked to avoid binding with the rotor vane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock pin is moved to the locked position by venting fluid or supplying pressure just prior to engine shutdown, then the lock pin engages the recess in the end plate to prevent movement, but oil leaks from the advance or retard chambers through the front cam bearing and/or oil control valve clearance, causing delayed oil pressure buildup and excessive wear on engine restart
Solution Approach 1:
The patent extracts the oil leakage problem by introducing a separate shutoff valve that isolates the advance and retard chambers from the oil control valve and front cam bearing. This shutoff valve is positioned to prevent oil from escaping through the clearance paths that exist in conventional systems, thereby maintaining oil within the chambers during shutdown and restart cycles.
Solution Approach 2:
The shutoff valve acts as an intermediary component between the advance and retard chambers and the external oil control system. By positioning this valve to close off communication paths, it mediates the oil flow to prevent leakage while still allowing controlled oil supply when needed for lock pin actuation and phaser operation.
2Productivity
If oil pressure is applied simultaneously to unlock the lock pin and actuate the rotor vane, then the phaser can change timing position, but the oil pressure torque on the rotor vane binds the lock pin against the receiver, causing delay or prevention of lock pin unlocking
Solution Approach 1:
The patent segments the oil pressure application into two separate functions: one path for unlocking the lock pin and another path for actuating the rotor vane. The shutoff valve is positioned to control oil flow to the vane, while a separate oil supply path provides pressure to unlock the lock pin without the vane being in the way to create binding torque.
Solution Approach 2:
The system performs preliminary action by unlocking the lock pin before applying oil pressure to actuate the rotor vane. The shutoff valve configuration allows oil to first reach the lock pin mechanism to release it, and only after unlocking does oil pressure get applied to the vane for phaser actuation, preventing the binding condition.
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
Prevents oil leakage, maintains oil within the phaser after shutdown, reduces wear, and eliminates premature binding of the lock pin, thereby enhancing start-up performance and reducing noise and vibration issues.
Implementation Method 1
an oil pressure actuated or torsion assisted phaser with a lock pin which has a position that shuts off communication between the advance and retard chambers and the front cam bearing and/or oil control valve
Implementation Method 2
when commanded to unlock, the oil pressure simultaneously acts on the lock pin to unlock
Implementation Method 3
The OCV directs engine oil pressure to one working chamber in the VCT phaser while simultaneously venting the opposing working chamber defined by the housing assembly, the rotor assembly, and the vane. This creates a pressure differential across one or more of the vanes to hydraulically push the VCT phaser
Data Source
AI summary
An oil pressure actuated or torsion assisted phaser with a lock pin that has a position which shuts off communication between the advance and retard chambers and the front cam bearing and/or oil control valve, effectively acting as a shutoff valve and preventing leakage of oil from the advance and retard chambers. The prevention of leakage maintains oil in the phaser after engine shutdown. Additionally, by shutting off communication between the advance and retard chambers and the oil supply, the side load on the lock pin from the oil pressure torque on the rotor vanes during unlocking of the lock pin can be reduced or eliminated.