Concentric Camshaft Phaser Arrangement for Independent Valve Timing
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Solution Overview
Problem
Concentric camshaft assemblies with a single camshaft configured to actuate both intake and exhaust valves face challenges in independent phasing due to axial packaging constraints in internal combustion engines, making it difficult to maintain optimal functionality.
Innovation Solution
A camshaft phaser arrangement featuring a first camshaft phaser non-rotatably connected to both inner and outer camshafts, and a second camshaft phaser connected to one of them, allowing for independent phasing with a reduced axial packaging space, utilizing a combination of electric and hydraulic phasers with specific components like output gears, follower components, and power transmission interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a single camshaft is used to actuate both intake and exhaust valves, then the axial packaging space is reduced, but independent phasing of intake and exhaust valves becomes difficult to achieve
Solution Approach 1:
The single camshaft is segmented into two separate concentric camshafts (inner camshaft and outer camshaft), each capable of independent rotation and phasing. This segmentation allows independent control of intake and exhaust valve timing while maintaining a compact axial footprint, as the concentric arrangement uses the same radial space more efficiently.
Solution Approach 2:
The inner camshaft is nested within the outer camshaft in a concentric arrangement, with the inner camshaft having a smaller diameter and being positioned coaxially inside the outer camshaft. This nesting configuration reduces the overall axial packaging space compared to using two separate camshafts stacked axially, while still enabling independent phasing of each camshaft.
2Adaptability or versatility
If two camshaft phasers are stacked coaxially at an end of the concentric camshaft assembly, then independent phasing is achieved, but packaging difficulty increases
Solution Approach 1:
Instead of stacking two phasers axially (one-dimensional arrangement), the solution transitions to a concentric radial arrangement where the inner camshaft with its phaser is positioned radially inside the outer camshaft with its phaser. This dimensional change from axial stacking to radial nesting reduces packaging difficulty while maintaining independent phasing capability.
3Length of stationary object
If a first camshaft phaser is non-rotatably connected to both inner and outer camshafts, then compact packaging is achieved, but the complexity of the phaser connection increases
Solution Approach 1:
The first camshaft phaser is designed with multi-functionality to serve dual purposes: it is non-rotatably connected to both the inner camshaft and the outer camshaft simultaneously. This universal connection approach allows a single phaser component to control both camshafts, reducing the total number of phasers needed and minimizing axial packaging space, while the added connection complexity is offset by the reduction in overall component count.
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
Enables independent phasing of intake and exhaust valves, optimizing engine performance and emissions while minimizing axial space, through the strategic connection of camshaft phasers and their components, facilitating flexible control over valve timing.
Implementation Method 1
Hydraulically actuated camshaft phasers can be configured with a rotor and stator arrangement
Implementation Method 2
Electric camshaft phasers can be configured with a gearbox and an electric motor to phase a camshaft
Data Source
AI summary
A camshaft phaser arrangement configured for a concentric camshaft assembly having inner and outer camshafts is provided. The camshaft phaser arrangement includes a first camshaft phaser that is configured to be non-rotatably connected to both the inner and outer camshafts, and a second camshaft phaser that is configured to be non-rotatably connected to one of the inner or outer camshafts.