Scroll Compressor Tip Clearance Gradient Design
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Solution Overview
Problem
Existing scroll compressors face challenges in optimizing tip clearance to match temperature and pressure gradients, leading to inefficiencies in compression performance due to gas leakage, especially when considering thermal expansion and pressure deformation.
Innovation Solution
The scroll compressor design features stepwise or continuous reduction in spiral wrap height and tip clearance on both the outer and inner circumference sides, with larger tip clearances on the inner side, and the use of tip seal members with varying height differences to minimize gas leakage across the temperature and pressure range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tip clearance on the inner circumference side is made larger than on the outer circumference side to consider thermal expansion, then the gas leakage is reduced to improve compression efficiency, but it becomes difficult to follow the continuous temperature gradient from intake to discharge temperature
Solution Approach 1:
The patent applies local quality by making the tip clearance vary continuously from the outer circumference side to the inner circumference side of the spiral wrap. Specifically, the tip clearance is designed to be larger on the inner circumference side where temperatures are higher, and smaller on the outer circumference side where temperatures are lower. This continuous variation in local clearance matches the continuous temperature gradient, allowing optimal sealing at each location while accommodating thermal expansion differences.
Solution Approach 2:
The patent implements dynamics by designing the tip clearance as a continuous gradient rather than a fixed uniform value. The clearance dynamically adapts to the temperature distribution across the spiral wrap, with the clearance magnitude varying continuously from outer to inner circumference. This dynamic design allows the system to respond to the continuous temperature gradient, improving both gas leakage prevention and temperature gradient matching simultaneously.
2Productivity
If the spiral wrap height is made higher on the outer circumference side than on the inner circumference side to enable three-dimensional compressions, then the compression ratio is increased to improve compression performance, but the end plates become thin on the outer circumference side and thick on the inner circumference side causing non-uniform pressure deformations
Solution Approach 1:
The patent applies local quality by creating a non-uniform spiral wrap height distribution, with the wrap height being larger on the outer circumference side and smaller on the inner circumference side. This local variation in wrap height enables three-dimensional compression while the corresponding end plate thickness variation is compensated by the gradual tip clearance increase toward the inner circumference, maintaining overall structural stability and uniform pressure deformation characteristics.
3Loss of energy
If the tip seal members are fitted in tip seal grooves with varying height differences to optimize tip clearance, then the gas leakage is minimized across the temperature and pressure range, but the device complexity increases
Solution Approach 1:
The patent applies local quality by fitting tip seal members in tip seal grooves with height differences that vary from the outer circumference side to the inner circumference side. The height difference is designed to be larger on the inner circumference side where temperatures are higher, and smaller on the outer circumference side. This local variation in seal member height optimizes the tip clearance at each location, minimizing gas leakage while adapting to the temperature and pressure gradient across the compressor.
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 optimizes tip clearance to reduce gas leakage, enhancing compression efficiency and achieving high performance by matching thermal expansion and pressure deformation across the compressor's operational range.
Implementation Method 1
the tip clearance on the inner circumference side with respect to the step portion is made larger than the tip clearance on the outer circumference side with respect to the step portion by considering the level of the thermal expansions of the paired scroll members
Implementation Method 2
the end plates are thin on the outer circumference side and thick on the inner circumference side, so that the pressure deformations of the end plates are not related unlike those of the uniform end plate thickness such the pressure rise and the deformation are substantially proportional
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
Intended is to provide a scroll compressor capable of performing three-dimensional compressions, which can optimize a tip clearance in operation while considering a thermal expansion and a pressure deformation and which can reduce a compression leakage to improve a compression efficiency thereby to realize a high performance. The leading end faces (13c and 13d) and the bottom face of a spiral wrap (13b) have a step portion (13e), and the wrap height on the outer circumference side of the spiral wrap (13b) is made larger than that on the inner circumference side wrap height, so that the scroll compressor can perform three-dimensional compressions capable of compressing in the circumferential direction of the spiral wrap (13b) and in the wrap height direction. The spiral wrap (13b) on the inner circumference side with respect to the step portion (13e) is stepwise or continuously made gradually lower toward the center side of the spiral wrap (13b), and the tip clearance (Δi) of the spiral wrap on the inner circumference side with respect to the step portion (13) is made gradually larger toward the center side of the spiral wrap (13b).