Scroll Compressor Bearing Clearance for Eccentric Shaft Loads
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Solution Overview
Problem
Conventional scroll compressors experience performance deterioration and increased friction due to eccentricity of the rotary shaft caused by driving loads, leading to uneven oil film formation and reduced durability.
Innovation Solution
The scroll compressor design incorporates a casing with a drive motor, a rotary shaft, a main frame, a fixed scroll, and an orbiting scroll, featuring first and second bearings with varying gaps and diameters to accommodate the eccentric rotary shaft, ensuring uniform oil distribution and reduced friction through journal bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotary shaft is eccentrically disposed to enable the orbiting scroll to revolve around the fixed scroll for compression, then the compression function is achieved, but the rotary shaft bends during rotation causing bearing performance deterioration and increased friction
Solution Approach 1:
The bearing inner diameter is designed to be larger than the rotary shaft diameter, creating a radial gap that accommodates shaft bending. This parameter change allows the bearing to tolerate eccentricity-induced shaft deflection without contact, preventing performance deterioration while maintaining compression functionality.
2Reliability
If the bearing inner diameter is made larger than the rotary shaft diameter to prevent contact, then friction is reduced, but the gap between bearing and shaft increases causing oil film formation issues
Solution Approach 1:
The bearing and rotary shaft are designed with asymmetric dimensional relationship where the bearing inner diameter is intentionally larger than the shaft diameter. This asymmetric gap design, combined with the bearing's positional variation, creates optimal oil film distribution that reduces friction while ensuring reliable lubrication throughout the rotation cycle.
3Device complexity
If the bearing position is fixed relative to the main frame and fixed scroll, then the structure is simple, but the rotary shaft bending causes uneven contact and increased friction
Solution Approach 1:
The bearing is designed with vertical position variation capability, allowing it to dynamically adjust its position relative to the rotary shaft during operation. This dynamic positioning compensates for shaft bending caused by eccentricity, maintaining optimal clearance and reducing friction without requiring complex active control mechanisms.
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 prevents bearing performance deterioration, reduces noise, and enhances the compressor's service life by minimizing friction and maintaining compression efficiency.
Implementation Method 1
The scroll compressor includes first and second bearings spaced apart from each other in a vertical direction and having inner diameters different from each other, thereby compensating for eccentricity of the rotary shaft caused by a driving load
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
Disclosed herein is a scroll compressor including a casing, a drive motor arranged in an inner space of the casing, a rotary shaft coupled to the drive motor to rotate, a main frame arranged under the drive motor, a fixed scroll arranged under the main frame, an orbiting scroll engaging with the orbiting scroll to make an orbiting motion, the rotary shaft being inserted into and eccentrically coupled to the orbiting scroll, a first bearing positioned between the main frame and the rotary shaft, and a second bearing positioned between the fixed scroll and the rotary shaft, wherein a gap between the first and second bearings and the rotary shaft varies with a vertical position. The scroll compressor may prevent the eccentric effect occurring during rotation from deteriorating performance of the bearings, thereby preventing compression performance from being lowered.