Variable Camshaft Phaser With Three Ring Gears
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable camshaft timing (VCT) systems face challenges in balancing loads across planet gears, leading to potential misalignment and increased frictional losses, which can affect the efficiency and reliability of engine valve timing adjustments.
Innovation Solution
A variable camshaft timing phaser design incorporating a planetary gear set with three ring gears that transmit substantially balanced loads across planet gears, eliminating the need for a carrier assembly and minimizing misalignment, while an electric motor drives the sun gear to advance or retard the camshaft timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional planetary gear set with two ring gears is used, then the structure is simpler, but the loads on planet gears are unbalanced causing misalignment and increased friction
Solution Approach 1:
The single ring gear is segmented into three separate ring gears (first, second, and third ring gears) that engage with planet gears at different axial sections. This segmentation allows independent load distribution to each ring gear, enabling balanced loading across all planet gears and preventing misalignment while maintaining reliable operation.
Solution Approach 2:
The patent introduces an axial dimension to the load distribution by engaging ring gears at different axial sections of the planet gears. Instead of balancing loads in a single plane, the loads are distributed across multiple axial levels, creating a three-dimensional load balance that eliminates misalignment issues.
2Reliability
If a carrier assembly is used to support planet gears, then the structure is more robust, but the phaser becomes heavier and more expensive
Solution Approach 1:
The carrier assembly is completely removed from the design. Instead of using a carrier to support and position the planet gears, the planet gears are directly supported by the balanced loading from the three ring gears. This extraction of the carrier assembly significantly reduces the phaser weight and component count while maintaining reliability through the alternative support mechanism.
Solution Approach 2:
The three ring gears themselves provide the support function that would traditionally be performed by a carrier assembly. By distributing loads balancedly across the planet gears through multiple ring gears, the system makes the planet gears self-supported, eliminating the need for an additional carrier structure.
3Productivity
If unbalanced loads are transmitted to planet gears, then the structure is simpler, but frictional losses increase and efficiency decreases
Solution Approach 1:
The load transmission path is segmented into three separate ring gear interfaces instead of one. This allows the total load to be distributed and balanced across multiple engagement points, reducing individual gear contact stresses and minimizing frictional losses at each interface, thereby improving overall phaser efficiency.
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 ensures precise and efficient angular displacement of the camshaft, reduces frictional losses, and allows for a lighter and more cost-effective phaser construction by balancing loads across planet gears, enhancing engine performance and fuel efficiency.
Implementation Method 1
a planetary gear set with three ring gears that transmit substantially balanced loads across planet gears
Implementation Method 2
an electric motor drives the sun gear to advance or retard the camshaft timing
Data Source
AI summary
An engine variable camshaft timing phaser (10) includes a sprocket (12), three ring gears (26, 28, 30), multiple planet gears (24), and a sun gear (22). The sprocket (12) receives rotational drive input from an engine crankshaft. One or more of the three ring gear(s) (26, 28, 30) receives rotational drive input from the sprocket (12) and rotates with the sprocket (12), and the remaining ring gear(s) (26, 28, 30) transmit rotational drive output to an engine camshaft (62). All three of the ring gears (26, 28, 30) engage with the planet gears (24). And the sun gear (22) also engages with the planet gears (24). In operation, relative rotational speeds between the sprocket (12) and the sun gear (22) causes the engine camshaft (62) to advance or retard engine valve opening and closing.