Scroll Compressor Shaft Knurling for Impact Noise Reduction
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Solution Overview
Problem
Conventional scroll compressors generate unnecessary noise and vibration due to impact between the eccentric bush and shaft when the rotation speed decreases or the shaft is stopped, causing friction and collision.
Innovation Solution
The introduction of a temporary contact part and a non-contact part on the shaft, formed through a knurling process, which minimizes the contact area with the eccentric bush, allowing for point contact and oil film formation to reduce noise and vibration when the shaft is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a rotation gap is provided between the shaft and eccentric bush, then the shaft can rotate smoothly during operation, but impact sound and noise are generated when the shaft stops due to inertia of the eccentric bush
Solution Approach 1:
The end-part outer circumferential surface of the shaft is given a different local quality by forming a temporary contact part through knurling process. This creates a localized rough surface that increases friction specifically at the contact point, causing the shaft to stop together with the eccentric bush rather than allowing the eccentric bush to strike the shaft due to inertia. This resolves the contradiction by maintaining smooth rotation during operation while preventing impact noise during stopping.
2Force
If the contact area between shaft and eccentric bush is increased, then friction is reduced during operation, but impact force increases when the shaft stops
Solution Approach 1:
Instead of uniformly increasing the contact area, the invention applies local quality change by creating a temporary contact part with increased surface roughness through knurling. This localized modification increases the friction coefficient at the contact interface without significantly increasing the contact area, thereby reducing friction during operation while limiting impact force during stopping.
Solution Approach 2:
The invention changes the physical parameter of the shaft surface by forming a temporary contact part with altered surface characteristics. The knurling process modifies the surface roughness and friction properties locally, enabling the shaft to maintain adequate friction during rotation while reducing the severity of impact when stopping, thus resolving the contradiction between friction force and impact resistance.
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 design significantly reduces noise and vibration by minimizing the impact sound and maintaining a stable oil film, enhancing the durability and operation stability of the scroll compressor.
Implementation Method 1
a temporary contact part (31a) formed on an end-part outer circumferential surface such that a part of the entire end-part outer circumferential surface of the shaft (31) comes into contact with the inner circumferential surface of the eccentric bush (32)
Data Source
AI summary
Provided is a scroll compressor which has a reduced noise vibration by minimizing an impact sound generated when the operation of the scroll compressor is stopped.