Oldham Coupling Key Recess Reduces Pressure Loading
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Solution Overview
Problem
Oldham couplings in scroll compressors often experience fatigue failure due to wear and poor lubrication conditions, leading to increased pressure loading and potential web fracture, which existing solutions have not adequately addressed without increasing compressor diameter or inertia.
Innovation Solution
The Oldham coupling structure features recessed key faces and extended key slots on the orbiting scroll base plate, increasing key height and area without enlarging the compressor diameter, thereby reducing pressure loading and inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If key surface area is increased by increasing key length, then pressure loading is decreased, but compressor diameter and Oldham coupling diameter increase
Solution Approach 1:
The patent transitions from increasing key length (one dimension) to increasing key height (another dimension) to increase the key surface area. This dimensional shift allows pressure loading reduction without increasing the compressor diameter, as the additional load-bearing area is achieved through vertical key height increase rather than horizontal key length extension.
Solution Approach 2:
The Oldham coupling is segmented into a ring portion and a hub portion, with the key face recessed into the ring portion. This segmentation allows the key surface area to be increased through vertical extension into the ring portion without increasing the overall compressor diameter, as the additional area is obtained through radial depth rather than tangential length.
2Stress or pressure
If key surface area is increased by increasing key height, then pressure loading is decreased, but orbiting scroll base plate thickness and inertia loads increase
Solution Approach 1:
The orbiting scroll base plate is segmented by adding a separate pad that extends the key slot. This allows the key height to be increased for reduced pressure loading while the additional mass is confined to a localized pad rather than increasing the overall base plate thickness, thereby minimizing the increase in orbiting scroll inertia.
Solution Approach 2:
The key slot extension is implemented locally through an added pad rather than uniformly increasing the entire base plate thickness. This localized approach provides the necessary increased key surface area for reduced pressure loading while minimizing the overall mass increase and resulting inertia loads of the orbiting scroll assembly.
3Reliability
If wear resistant coatings are applied to keys, then key wear is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of changing the material properties through wear resistant coatings, the patent changes the geometric parameters of the key - specifically increasing the key height and recessing the key face. This geometric modification increases the key surface area to reduce pressure loading and wear, while avoiding the manufacturing complexity and cost associated with applying specialized coatings.
Data Source
AI summary
An Oldham coupling structure for a scroll compressor decreases Oldham coupling pressure loading without increasing compressor diameter or significantly increasing orbiting scroll or Oldham coupling inertia. The Oldham coupling key height and area are increased by recessing the key face into the ring portion of the Oldham coupling, increasing the key height and adding pads to the involute side of the orbiting scroll base plate to extend the key slot, potentially resulting in reduced compressor diameter and/or reduced orbiting scroll and Oldham coupling inertia.