Harmonic Drive Camshaft Phaser Radial Stiffeners
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Solution Overview
Problem
Existing oil-less camshaft phasers are bulky, complex, and lack a default phase position mechanism, leading to limited phase authority and potential failure under radial loading or bending, which can cause housing distortion and gear reducer binding.
Innovation Solution
The implementation of radial housing stiffeners and a knurled press fit joint to provide additional support to the journal bearing and harmonic gear drive unit, minimizing housing distortion without increasing bulk, and ensuring axial stability and resistance to radial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional radial support is provided for the journal bearing and harmonic gear drive unit, then housing distortion is reduced and structural integrity is improved, but housing bulk increases
Solution Approach 1:
The patent applies radial stiffeners that extend in the radial dimension to provide housing support. These stiffeners are formed as integral portions of the housing and project radially outward to reinforce the housing against bending and distortion, without requiring additional axial or circumferential bulk.
Solution Approach 2:
The housing is segmented into multiple reinforced zones by incorporating discrete radial stiffeners at specific locations. This segmentation allows targeted reinforcement where needed (at the journal bearing and HD support locations) without uniformly increasing the entire housing bulk.
2Strength
If a knurled press fit joint is used to secure the back plate, then radial support is enhanced without select fitting, but manufacturing complexity increases
Solution Approach 1:
The patent applies a knurled surface pattern to the back plate, which fundamentally changes the friction and engagement parameters of the press fit joint. This knurling allows standard press fit tolerances to achieve enhanced radial support without requiring selective fitting or complex machining operations.
3Adaptability or versatility
If the harmonic drive unit is exposed to radial loading or bending, then phase authority is maintained, but the flex spline surface may yield and binding occurs
Solution Approach 1:
The patent incorporates radial stiffeners and enhanced housing support structures that preemptively counteract radial loading and bending forces before they can cause the flex spline surface to yield. This preliminary reinforcement prevents binding by maintaining proper clearance and alignment under load.
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 solution enhances the structural integrity and stability of the camshaft phaser, reducing the risk of failure due to radial loading and bending, while maintaining a compact design and reducing manufacturing costs.
Implementation Method 1
a knurled surface applied to an axial surface of the back plate... the knurl engages the housing bore radially
Implementation Method 2
the knurl engages the housing bore radially... providing additional support to the journal bearing
Implementation Method 3
radial housing stiffeners... to prevent distortion of the spline ring... resistance to radial forces
Data Source
AI summary
Improved stiffening and minimized distortion of a housing for an eVCP achieved by forming a plurality of radial housing stiffeners into the housing around the motor mount end and into the eVCP's hub. A back plate is press fit into the rear of the housing, and a straight axial knurl is applied to the surface of the back plate or housing, which knurl permits a larger tolerance-higher press fit class to be used without resulting in significant deformation of the housing. The knurled back plate is harder than the housing, causing the high points of the knurl to plastically deform or plow the housing material during assembly, resulting in less radial deformation of the bore and the journal bearing. An interface between the housing and the hub provides a journal bearing interface to improve axial stability between the hub and housing.