Camshaft Phaser Stator Clamping via Compression Limiters
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Solution Overview
Problem
Existing camshaft phasers with stators having fewer lobes or non-equally spaced lobes face inadequate clamping force and sealing issues due to cover bolts passing through apertures, and stators made using powder metal processes struggle with forming radially extending ribs, which add weight and complicate manufacturing.
Innovation Solution
The camshaft phaser design incorporates a stator with inwardly extending lobes and a rotor with outwardly extending vanes, featuring compression limiters that extend through stator flange apertures to apply a clamping load between the front and back covers, allowing for adjustable placement of fasteners to ensure an adequate seal and reducing weight by eliminating radially extending ribs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cover bolts pass through apertures in lobes to clamp the stator, then the stator is secured between covers, but adequate clamping force and sealing are not achieved when stators have fewer lobes or non-equally spaced lobes
Solution Approach 1:
The stator is segmented into a hub portion and a flange portion, with the flange providing a dedicated clamping surface. This segmentation allows the clamping mechanism to be independent of the lobe configuration, enabling adequate sealing regardless of the number or spacing of lobes.
Solution Approach 2:
The flange acts as an intermediary element between the cover bolts and the hub. The clamping force is applied to the flange rather than directly to the lobes, allowing the sealing performance to be maintained across various stator designs with different lobe configurations.
2Force
If radially extending ribs are added to accommodate cover bolts, then clamping force is provided, but stator weight increases and manufacturing complexity increases for powder metal processes
Solution Approach 1:
The stator is divided into functional portions: the hub for rotational function and the flange for clamping function. This segmentation eliminates the need for radially extending ribs, reducing stator weight while maintaining adequate clamping force through the flange structure.
Solution Approach 2:
The flange serves multiple functions: it provides a clamping surface for cover bolts, maintains structural integrity, and enables sealing without requiring additional rib structures. This multi-functionality achieves clamping force provision while minimizing weight and manufacturing complexity.
3Ease of manufacture
If radially extending ribs are formed in powder metal stators, then cover bolt accommodation is enabled, but manufacturing difficulty increases
Solution Approach 1:
The stator structure is segmented with a dedicated flange portion that is inherently suitable for powder metal manufacturing. This flange provides cover bolt accommodation without requiring complex radially extending ribs, simplifying the manufacturing process while maintaining structural functionality.
Data Source
AI summary
A camshaft phaser includes a stator having an inner wall with lobes extending radially inward and a stator flange extending radially outward, the stator flange having a plurality of apertures; a rotor coaxially disposed within the stator, the rotor having vanes interspersed with the lobes defining alternating advance chambers and retard chambers; a plurality of compression limiters extending through the apertures; a front cover which closes one end of the advance and retard chambers; a back cover which closes the other end of the advance and retard chambers; and a plurality of fasteners which extend through the apertures such that the fasteners apply a clamping load which clamps the stator between the front cover and the back cover such that the clamping load is transmitted through the compression limiters.