Scroll Compressor Eccentric Shaft Base Seat Design
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Solution Overview
Problem
In scroll compressors, the eccentric shaft experiences high stress at the boundary portion with the fitting hole, leading to potential strength reduction and an increased radial size of the drive bush, making it difficult to decrease the outer diameter of the eccentric shaft.
Innovation Solution
The design includes a base seat portion with a press-fitting hole on the shaft, allowing the eccentric shaft to be press-inserted into a penetration portion with a gap between the drive bush body, enhancing the eccentric shaft's strength, reducing its diameter, and minimizing friction, while a limit pin with a rubber ring regulates the drive bush's position and alleviates impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the eccentric shaft is supported in a cantilever state with a fitting hole, then the manufacturing is simplified, but high stress is generated at the base portion of the eccentric shaft reducing its strength
Solution Approach 1:
The penetration portion is divided into two distinct portions: a first portion with a smaller diameter that fits into the first hole portion of the shaft, and a second portion with a larger diameter that fits into the press-fitting hole of the base seat portion. This segmentation allows the eccentric shaft to be supported at two different locations, distributing the stress and improving strength while maintaining ease of manufacture.
2Volume of moving object
If the outer diameter of the eccentric shaft is decreased, then the radial size of the drive bush is reduced, but the strength of the eccentric shaft decreases due to high stress at the base portion
Solution Approach 1:
The base seat portion acts as an intermediary component that provides additional support to the eccentric shaft. By introducing this intermediate support structure with the press-fitting hole, the eccentric shaft can be made thinner without compromising strength, as the base seat portion shares the load and prevents excessive stress concentration.
3Volume of moving object
If the eccentric shaft is made thinner to reduce drive bush size, then the radial space is reduced, but the stress concentration at the base portion increases
Solution Approach 1:
The penetration portion is divided into two distinct portions: a first portion with a smaller diameter that fits into the first hole portion of the shaft, and a second portion with a larger diameter that fits into the press-fitting hole of the base seat portion. This segmentation allows the eccentric shaft to be supported at two different locations, distributing the stress and improving strength while maintaining ease of manufacture.
4Ease of operation
If a gap is introduced between the drive bush body and base seat portion, then friction is reduced and assembly is easier, but the structural rigidity may be compromised
Solution Approach 1:
The gap between the drive bush body and base seat portion effectively 'takes out' the frictional interaction between these two components. By separating them with a gap, the design eliminates the harmful friction while the eccentric shaft itself maintains the necessary structural rigidity through its dual support configuration. The gap prevents binding and facilitates assembly without compromising the load-bearing path through the eccentric shaft and base seat portion.
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 configuration improves the eccentric shaft's strength, reduces the radial size of the drive bush, decreases friction, and allows for a more compact design by shortening the eccentric shaft and using inexpensive materials like cast iron for the drive bush.
Implementation Method 1
the eccentric shaft is fitted into the first hole portion and the first portion and is press-inserted into the press-fitting hole
Data Source
AI summary
A scroll compressor includes a base seat portion which is integrally formed with one end surface of a shaft and in which a press-fitting hole exposing a first hole portion is formed. The base seat portion is disposed in a second portion of a penetration portion with a gap interposed between a drive bush body and the base seat portion.