Dual VCT Phaser Radial Stacking Axial Space
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Solution Overview
Problem
Dual variable cam timing (VCT) devices face challenges in requiring additional axial space and experiencing reduced angular actuation distance and force due to limited vane surface area and chamber size, particularly in configurations with axially or circumferentially spaced variable volume working chambers.
Innovation Solution
A dual variable cam timing phaser 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 distance and force capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If variable volume working chambers are positioned axially spaced with respect to one another in dual VCT devices, then the angular actuation distance and actuation force are improved, but additional axial space is required
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 achieve the benefits of increased angular actuation distance and force while eliminating the need for additional axial space, as the chambers are arranged around the camshaft in a radial pattern rather than extending axially.
Solution Approach 2:
The patent employs a nested configuration where the second working chamber is positioned within the radial envelope of the first working chamber, with the chambers stacked radially rather than axially. This nesting approach allows both chambers to coexist in a compact radial space, achieving the required actuation force and angular displacement without increasing axial dimensions.
2Length of moving object
If variable volume working chambers are positioned circumferentially spaced with respect to one another in dual VCT devices, then axial space requirements are reduced, but angular actuation distance and actuation force are reduced
Solution Approach 1:
The patent resolves this contradiction by changing the spatial arrangement from circumferential spacing to radial stacking. This dimensional change allows the working chambers to be positioned such that they share axial space while maintaining sufficient radial separation for effective vanes and hydraulic fluid communication, thereby achieving both compact axial footprint and adequate actuation force.
Solution Approach 2:
The patent segments the dual VCT assembly into two independently controllable working chambers that are radially stacked. Each chamber has its own vanes and hydraulic fluid passages, allowing independent operation and control. This segmentation enables the system to achieve the required actuation force for each camshaft timing control while maintaining a compact axial configuration.
3Device complexity
If limited number of vanes and limited vane surface area are used in dual VCT devices, then device complexity is reduced, but angular actuation distance and actuation force are reduced
Solution Approach 1:
The patent employs hydraulic fluid under pressure to actuate the vanes in the working chambers. The hydraulic system provides the necessary force multiplication, allowing a limited number of vanes with moderate surface area to generate sufficient actuation force. The pressurized hydraulic fluid acts on the vane surfaces to create the required torque for camshaft timing adjustment, reducing the need for a large number of vanes while maintaining adequate actuation force.
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 enables more compact and efficient dual VCT assemblies with increased angular actuation distances and forces, improving engine performance by allowing independent phase adjustment of camshafts relative to the crankshaft.
Implementation Method 1
vane-type hydraulic couplings... hydraulic fluid is admitted into and expelled from the various chambers, the vanes rotate relative to one another and thereby vary the relative angular position of the drive member and the single driven member
Data Source
AI summary
A variable cam timing phaser for an internal combustion engine having a concentric camshaft can include a stator (14) having an axis of rotation. An outer rotor (20) can rotate independently relative to the axis of rotation of the stator (14). A combination of an outer vane (22) and cavity (20a) can be associated with the outer rotor (20) to define first and second outer variable volume working chambers (20b, 20c). A radially inner located rotor (30) can rotate relative to the axis of rotation and independently of both the stator (14) and the outer rotor (20). A combination of an inner vane (32) and a cavity (30a) can be associated with the inner rotor (20) to define first and second inner variable volume working chambers (30b, 30c). When the first and second, outer and inner chambers (20b, 30b, 20c, 30c) selectively communicate with a source of pressurized fluid, phase orientation of the outer and inner rotors (20, 30) with respect to one another and with respect to the stator (14) is facilitated.