Variable Camshaft Timing System Radial Movement Mechanism
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Solution Overview
Problem
Variable camshaft timing systems with concentric camshafts often experience binding issues due to the relative movement between inner and outer camshafts, which hinders smooth angular displacement and efficient engine operation.
Innovation Solution
A variable camshaft timing system incorporating an independent camshaft phaser and a dependent camshaft phaser with a half-Oldham link and pivotable arms, allowing radial movement between the camshafts to prevent binding, enabling precise control of angular position through motion variables and Oldham coupling mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If VCT devices are directly attached to one end of the camshaft to change angular position, then camshaft timing control is achieved, but concentric camshafts may bind and not be easily angularly displaced relative to each other
Solution Approach 1:
The patent introduces an intermediary mechanism (the dependent camshaft phaser with half-Oldham link and pivotable arms) between the independent camshaft phaser and the concentric camshafts. This intermediary allows the inner camshaft to move radially relative to the outer camshaft during angular displacement, preventing binding while still achieving precise camshaft timing control through the VCT device.
2Productivity
If concentric camshafts are used to allow angular displacement relative to each other, then valve operation efficiency is improved, but tolerance or space between camshafts causes binding during relative movement
Solution Approach 1:
The patent applies dynamics by making the camshaft phaser mechanism dynamic rather than rigid. The half-Oldham link and pivotable arms create a dynamic connection that allows the inner camshaft to radially move relative to the outer camshaft during operation. This dynamic adjustment accommodates tolerance variations and prevents binding, ensuring reliable smooth operation while maintaining efficient valve actuation.
Data Source
AI summary
A variable camshaft timing (VCT) system includes an independent camshaft phaser, receiving input from a crankshaft of an internal combustion engine, having an output coupled to one of an inner concentric camshaft or an outer concentric camshaft; and a dependent camshaft phaser, coupled to the other of the inner concentric camshaft or the outer concentric camshaft, comprising a half-Oldham link configured to permit radial movement of the inner concentric camshaft relative to the outer concentric camshaft in one radial direction and at least one pivotable arm configured to permit radial movement of the inner concentric camshaft relative to the outer concentric camshaft in another, different radial direction.