Radially Stacked Dual VCT Phaser for Compact Axial Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dual variable cam timing (VCT) devices face challenges with increased axial space requirements and reduced angular actuation distances and forces due to limited vane surface area and actuation fluid chamber size.
Innovation Solution
A dual variable cam timing phaser configuration with radially stacked vane-type hydraulic couplings, allowing independent rotation of concentric driven rotors relative to a drive stator, which reduces axial space requirements and enhances angular actuation distances and forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dual VCT devices are configured with axially spaced variable volume working chambers, then the assembly requires additional axial space, but the angular actuation distance and actuation force are reduced
Solution Approach 1:
The patent transitions from axial stacking of working chambers to radial stacking, changing the spatial arrangement from one dimension (axial) to another dimension (radial). This allows the dual VCT assembly to maintain compact axial dimensions while providing sufficient space for both working chambers and their associated vanes, thereby preserving actuation force capabilities.
Solution Approach 2:
The patent implements a nested configuration where the inner rotor with its working chamber is positioned within the outer rotor assembly. The inner rotor's variable volume working chamber is radially inwardly spaced from the outer rotor's working chamber, creating a nested arrangement that maximizes space utilization and maintains actuation force while reducing axial dimensions.
2Length of moving object
If dual VCT devices are configured with circumferentially spaced variable volume working chambers, then the angular actuation distance is reduced, but the actuation force is limited by the number of vanes
Solution Approach 1:
The patent changes the spatial arrangement from circumferential spacing to radial spacing of the working chambers. This dimensional change allows both outer and inner rotors to have sufficient angular actuation distance while maintaining adequate vane surface area for generating actuation force, as the radial stacking provides independent space for each working chamber without circumferential interference.
3Force
If the vane surface area is limited in dual VCT devices, then the actuation force is reduced, but the angular actuation distance is also limited
Solution Approach 1:
The nested configuration with radially spaced working chambers allows each rotor to have its own dedicated vane surface area without interference from the other rotor. The outer rotor's vanes and the inner rotor's vanes operate in independent radial zones, enabling both to achieve sufficient actuation force while maintaining adequate angular actuation distance.
Solution Approach 2:
The patent segments the dual VCT assembly into distinct outer and inner rotors with separate working chambers and vane systems. This segmentation allows independent optimization of each rotor's vane surface area and angular actuation characteristics, enabling both to achieve sufficient actuation force and angular travel without mutual interference.
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 configuration provides a more compact dual VCT assembly with increased angular actuation distances and forces, improving engine performance by allowing independent phase adjustment of camshafts relative to the crankshaft.
Implementation Method 1
hydraulic couplings for single phaser assemblies in which an annular space is provided between a drive member concentrically surrounding a single driven member. The annular space is divided into segment-shaped or arcuate variable volume working chambers by one or more vanes extending radially inward from an inner surface of the drive member and one or more vanes extending radially outward from an outer surface of the single driven member. As hydraulic fluid is admitted into and expelled from the various chambers, the vanes rotate relative to one another
Implementation Method 2
variable volume working chambers that are positioned axially spaced with respect to one another require additional axial space for the dual VCT assembly, while those dual VCT devices with variable volume working chambers that are positioned circumferentially spaced with respect to one another
Data Source
AI summary
A variable cam timing phaser (10) includes a fluid transfer assembly with at least one of a fluid transfer sleeve (72) having a plurality of pressurized fluid passages (74a, 74b, 74c, 74d), and a fluid transfer plate (60) having a plurality of pressurized fluid passages (62a, 62b, 62c, 62d). Each passage (74a, 74b, 74c, 74d) extends in fluid communication with a corresponding circumferentially spaced annular groove segment portion (74f, 74g, 74h, 74i) for selective communication with first and second vane-type hydraulic couplings (40, 50) depending on an angular orientation of the fluid transfer sleeve (72) during rotation. Each passage (62a, 62b, 62c, 62d) extending from a corresponding centrally located port (64a, 64b, 64c, 64d) in fluid communication with a radially extending passage portion (66a, 66b, 66c, 66d) and with an arcuately extending passage portion (68a, 68b, 68c, 68d).