Variable Cam Timing Phaser Vent Path Against Air Ingestion
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Solution Overview
Problem
Conventional variable cam timing systems experience oscillation due to torsional forces causing air ingestion through the vent path, leading to reduced performance.
Innovation Solution
A control valve assembly with a vent path configured to prevent air ingestion by directing hydraulic fluid to a sump, reducing oscillation of the rotor during torque reversals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the exhaust port is fluidly connectable with a sump through a vent path in conventional control valve assemblies, then hydraulic fluid can be exhausted to the sump, but air may be drawn back into the advance or retard chamber through the vent path during torque reversals, causing rotor oscillation and decreased performance
Solution Approach 1:
A check valve is introduced as an intermediary component in the vent path between the exhaust port and the sump. This check valve allows hydraulic fluid to flow from the exhaust port to the sump while preventing air from the sump from flowing back into the advance or retard chamber, thereby eliminating the harmful air ingestion that causes rotor oscillation
Solution Approach 2:
The invention utilizes the directional flow characteristics of hydraulic fluid through the check valve mechanism, leveraging pneumatic and hydraulic principles to control fluid flow in one direction only, preventing air backflow while maintaining hydraulic fluid exhaustion functionality
2Ease of operation
If the rotor moves between advance and retard positions under torsional forces, then the camshaft can be controlled, but the vanes move back and forth within the chambers, overcoming hydraulic fluid pressure and causing oscillation
Solution Approach 1:
The check valve acts as a mediator that stabilizes the hydraulic fluid pressure in the advance and retard chambers by preventing air ingestion, thereby maintaining consistent hydraulic pressure that keeps the vanes stable and reduces rotor oscillation during camshaft control operations
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 vent path configuration minimizes air ingestion, ensuring smooth rotor rotation and improved performance by maintaining hydraulic fluid flow during torque reversals.
Implementation Method 1
the vent path is configured to prevent air from being sucked into the variable cam timing phaser through the vent path
Data Source
AI summary
A variable cam timing phaser of a variable cam timing system includes a housing and a rotor moveable with respect to the housing. The rotor and the housing define advance and retard chambers. The variable cam timing phaser also includes a control valve assembly. The control valve assembly includes a valve housing defining a valve housing interior, a supply port, first and second working ports, and an exhaust port. The control valve assembly also includes a piston moveable for controlling flow of the hydraulic fluid through the valve housing interior. The exhaust port is fluidly connectable with a sump through a vent path that is defined by at least one of the valve housing and the rotor. The vent path is configured to prevent air from being sucked into the variable cam timing phaser through the vent path.