Variable Cam Timing Phaser Chamber Biasing Assembly
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Solution Overview
Problem
Conventional variable cam timing systems face challenges in reducing emissions during the start-up of internal combustion engines, particularly due to issues with hydraulic fluid flow and locking mechanisms that can lead to delayed rotor movement and oil leakage.
Innovation Solution
The variable cam timing phaser incorporates a chamber biasing assembly with a chamber piston, biasing member, and check valve to bias the rotor into a predetermined position, eliminating the need for a locking pin and torsion spring, and optimizing hydraulic fluid flow to reduce emissions and improve cold temperature actuation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional variable cam timing systems use traditional locking mechanisms and hydraulic fluid flow control, then the system can maintain camshaft position, but emissions increase during start-up due to delayed rotor movement and oil leakage
Solution Approach 1:
The patent removes the locking pin mechanism from the rotor assembly, extracting the problematic component that caused delayed rotor movement. The locking function is replaced by the chamber biasing assembly that uses hydraulic pressure differentials to control rotor position, eliminating the mechanical locking mechanism that contributed to emissions during start-up.
Solution Approach 2:
The patent employs a chamber biasing assembly that uses hydraulic fluid pressure to control rotor movement and maintain position. The biasing assembly creates pressure differentials between chambers to drive the rotor to predetermined positions, providing responsive and reliable rotor control without mechanical locking components.
2Stability of the object's composition
If conventional systems use locking pins and torsion springs to maintain rotor position, then the rotor can be held in position, but the system complexity increases and oil leakage occurs
Solution Approach 1:
The patent merges the positioning and stabilizing functions into a single chamber biasing assembly that uses hydraulic pressure control. The biasing assembly combines the functions of position control and stability maintenance that were previously handled by separate locking pins and torsion springs, reducing overall system complexity while preventing oil leakage.
Solution Approach 2:
The patent replaces the mechanical locking pin and torsion spring system with a hydraulic chamber biasing assembly. This substitution eliminates complex mechanical components that caused oil leakage and position instability, using instead a streamlined hydraulic pressure-based system that provides reliable rotor position control.
3Speed
If conventional variable cam timing phasers use traditional hydraulic control, then the system can adjust camshaft timing, but cold temperature actuation speeds are reduced
Solution Approach 1:
The chamber biasing assembly is pre-configured to provide immediate hydraulic pressure differentials when activated, enabling rapid rotor movement even in cold temperature conditions. The biasing mechanism is designed to overcome high viscous resistance of cold hydraulic fluid, providing fast actuation speeds from a cold start 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
This design reduces emissions during engine start-up, enhances cold temperature actuation, and prevents oil leakage, allowing the rotor to move promptly and maintain the camshaft position without external corrections, thus improving the overall efficiency and reliability of the variable cam timing system.
Implementation Method 1
The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve configured to bias the rotor into a predetermined position between the advance and the retard positions
Implementation Method 2
a chamber check valve... configured to bias the rotor into a predetermined position... optimizing hydraulic fluid flow
Data Source
AI summary
A variable cam timing phaser includes a housing disposed about an axis and having an inner housing surface defining a housing interior. The variable cam timing phaser includes a rotor moveable between an advance position and a retard position. The rotor includes a hub and a vane, with the rotor and the housing defining a chamber. The vane further defines the chamber into an advance chamber and a retard chamber. The variable cam timing phaser also includes a control valve assembly including a valve housing and a control piston. The variable cam timing phaser also includes a chamber biasing assembly disposed in one of the advance and the retard chambers and configured to bias the rotor into a predetermined position between the advance and the retard positions. The chamber biasing assembly includes a chamber piston, a chamber biasing member, and a chamber check valve.